Ignore:
Timestamp:
14/06/14 11:20:37 (8 years ago)
Author:
julian.reschke@…
Message:

update to latest version of rfc2629.xslt, regen all HTML

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  • draft-ietf-httpbis/10/p2-semantics.html

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    347   } 
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    … …  
    391400      <link rel="Appendix" title="B Collected ABNF" href="#rfc.section.B">
    392401      <link rel="Appendix" title="C Change Log (to be removed by RFC Editor before publication)" href="#rfc.section.C">
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    394403      <link rel="schema.dct" href="http://purl.org/dc/terms/">
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    … …  
    420429            </tr>
    421430            <tr>
    422                <td class="left">Obsoletes: <a href="http://tools.ietf.org/html/rfc2616">2616</a> (if approved)
     431               <td class="left">Obsoletes: <a href="https://tools.ietf.org/html/rfc2616">2616</a> (if approved)
    423432               </td>
    424433               <td class="right">J. Gettys</td>
    425434            </tr>
    426435            <tr>
    427                <td class="left">Updates: <a href="http://tools.ietf.org/html/rfc2817">2817</a> (if approved)
     436               <td class="left">Updates: <a href="https://tools.ietf.org/html/rfc2817">2817</a> (if approved)
    428437               </td>
    429438               <td class="right">Alcatel-Lucent</td>
    … …  
    492501      </table>
    493502      <p class="title">HTTP/1.1, part 2: Message Semantics<br><span class="filename">draft-ietf-httpbis-p2-semantics-10</span></p>
    494       <h1 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h1> 
     503      <h1 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h1>
    495504      <p>The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information
    496505         systems. HTTP has been in use by the World Wide Web global information initiative since 1990. This document is Part 2 of the
    … …  
    498507         2 defines the semantics of HTTP messages as expressed by request methods, request-header fields, response status codes, and
    499508         response-header fields.
    500       </p> 
    501       <h1 id="rfc.note.1"><a href="#rfc.note.1">Editorial Note (To be removed by RFC Editor)</a></h1> 
     509      </p>
     510      <h1 id="rfc.note.1"><a href="#rfc.note.1">Editorial Note (To be removed by RFC Editor)</a></h1>
    502511      <p>Discussion of this draft should take place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org). The current issues
    503512         list is at &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/report/3">http://tools.ietf.org/wg/httpbis/trac/report/3</a>&gt; and related documents (including fancy diffs) can be found at &lt;<a href="http://tools.ietf.org/wg/httpbis/">http://tools.ietf.org/wg/httpbis/</a>&gt;.
    504       </p> 
     513      </p>
    505514      <p>The changes in this draft are summarized in <a href="#changes.since.09" title="Since draft-ietf-httpbis-p2-semantics-09">Appendix&nbsp;C.11</a>.
    506       </p>
    507       <h1><a id="rfc.status" href="#rfc.status">Status of This Memo</a></h1>
    508       <p>This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.</p>
    509       <p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute
    510          working documents as Internet-Drafts. The list of current Internet-Drafts is at <a href="http://datatracker.ietf.org/drafts/current/">http://datatracker.ietf.org/drafts/current/</a>.
    511515      </p>
    512       <p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other
    513          documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work
    514          in progress”.
    515       </p>
    516       <p>This Internet-Draft will expire on January 13, 2011.</p>
    517       <h1><a id="rfc.copyrightnotice" href="#rfc.copyrightnotice">Copyright Notice</a></h1>
    518       <p>Copyright © 2010 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
    519       <p>This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights
    520          and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License
    521          text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified
    522          BSD License.
    523       </p>
    524       <p>This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November
    525          10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to
    526          allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s)
    527          controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative
    528          works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate
    529          it into languages other than English.
    530       </p>
     516      <div id="rfc.status">
     517         <h1><a href="#rfc.status">Status of This Memo</a></h1>
     518         <p>This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.</p>
     519         <p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute
     520            working documents as Internet-Drafts. The list of current Internet-Drafts is at <a href="http://datatracker.ietf.org/drafts/current/">http://datatracker.ietf.org/drafts/current/</a>.
     521         </p>
     522         <p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other
     523            documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work
     524            in progress”.
     525         </p>
     526         <p>This Internet-Draft will expire on January 13, 2011.</p>
     527      </div>
     528      <div id="rfc.copyrightnotice">
     529         <h1><a href="#rfc.copyrightnotice">Copyright Notice</a></h1>
     530         <p>Copyright © 2010 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
     531         <p>This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights
     532            and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License
     533            text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified
     534            BSD License.
     535         </p>
     536         <p>This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November
     537            10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to
     538            allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s)
     539            controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative
     540            works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate
     541            it into languages other than English.
     542         </p>
     543      </div>
    531544      <hr class="noprint">
    532545      <h1 class="np" id="rfc.toc"><a href="#rfc.toc">Table of Contents</a></h1>
    533546      <ul class="toc">
    534          <li>1.&nbsp;&nbsp;&nbsp;<a href="#introduction">Introduction</a><ul>
    535                <li>1.1&nbsp;&nbsp;&nbsp;<a href="#intro.requirements">Requirements</a></li>
    536                <li>1.2&nbsp;&nbsp;&nbsp;<a href="#notation">Syntax Notation</a><ul>
    537                      <li>1.2.1&nbsp;&nbsp;&nbsp;<a href="#core.rules">Core Rules</a></li>
    538                      <li>1.2.2&nbsp;&nbsp;&nbsp;<a href="#abnf.dependencies">ABNF Rules defined in other Parts of the Specification</a></li>
     547         <li><a href="#rfc.section.1">1.</a>&nbsp;&nbsp;&nbsp;<a href="#introduction">Introduction</a><ul>
     548               <li><a href="#rfc.section.1.1">1.1</a>&nbsp;&nbsp;&nbsp;<a href="#intro.requirements">Requirements</a></li>
     549               <li><a href="#rfc.section.1.2">1.2</a>&nbsp;&nbsp;&nbsp;<a href="#notation">Syntax Notation</a><ul>
     550                     <li><a href="#rfc.section.1.2.1">1.2.1</a>&nbsp;&nbsp;&nbsp;<a href="#core.rules">Core Rules</a></li>
     551                     <li><a href="#rfc.section.1.2.2">1.2.2</a>&nbsp;&nbsp;&nbsp;<a href="#abnf.dependencies">ABNF Rules defined in other Parts of the Specification</a></li>
    539552                  </ul>
    540553               </li>
    541554            </ul>
    542555         </li>
    543          <li>2.&nbsp;&nbsp;&nbsp;<a href="#method">Method</a><ul>
    544                <li>2.1&nbsp;&nbsp;&nbsp;<a href="#method.registry">Method Registry</a></li>
     556         <li><a href="#rfc.section.2">2.</a>&nbsp;&nbsp;&nbsp;<a href="#method">Method</a><ul>
     557               <li><a href="#rfc.section.2.1">2.1</a>&nbsp;&nbsp;&nbsp;<a href="#method.registry">Method Registry</a></li>
    545558            </ul>
    546559         </li>
    547          <li>3.&nbsp;&nbsp;&nbsp;<a href="#request.header.fields">Request Header Fields</a></li>
    548          <li>4.&nbsp;&nbsp;&nbsp;<a href="#status.code.and.reason.phrase">Status Code and Reason Phrase</a><ul>
    549                <li>4.1&nbsp;&nbsp;&nbsp;<a href="#status.code.registry">Status Code Registry</a></li>
     560         <li><a href="#rfc.section.3">3.</a>&nbsp;&nbsp;&nbsp;<a href="#request.header.fields">Request Header Fields</a></li>
     561         <li><a href="#rfc.section.4">4.</a>&nbsp;&nbsp;&nbsp;<a href="#status.code.and.reason.phrase">Status Code and Reason Phrase</a><ul>
     562               <li><a href="#rfc.section.4.1">4.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.code.registry">Status Code Registry</a></li>
    550563            </ul>
    551564         </li>
    552          <li>5.&nbsp;&nbsp;&nbsp;<a href="#response.header.fields">Response Header Fields</a></li>
    553          <li>6.&nbsp;&nbsp;&nbsp;<a href="#entity">Entity</a><ul>
    554                <li>6.1&nbsp;&nbsp;&nbsp;<a href="#identifying.response.associated.with.representation">Identifying the Resource Associated with a Representation</a></li>
     565         <li><a href="#rfc.section.5">5.</a>&nbsp;&nbsp;&nbsp;<a href="#response.header.fields">Response Header Fields</a></li>
     566         <li><a href="#rfc.section.6">6.</a>&nbsp;&nbsp;&nbsp;<a href="#entity">Entity</a><ul>
     567               <li><a href="#rfc.section.6.1">6.1</a>&nbsp;&nbsp;&nbsp;<a href="#identifying.response.associated.with.representation">Identifying the Resource Associated with a Representation</a></li>
    555568            </ul>
    556569         </li>
    557          <li>7.&nbsp;&nbsp;&nbsp;<a href="#method.definitions">Method Definitions</a><ul>
    558                <li>7.1&nbsp;&nbsp;&nbsp;<a href="#safe.and.idempotent">Safe and Idempotent Methods</a><ul>
    559                      <li>7.1.1&nbsp;&nbsp;&nbsp;<a href="#safe.methods">Safe Methods</a></li>
    560                      <li>7.1.2&nbsp;&nbsp;&nbsp;<a href="#idempotent.methods">Idempotent Methods</a></li>
     570         <li><a href="#rfc.section.7">7.</a>&nbsp;&nbsp;&nbsp;<a href="#method.definitions">Method Definitions</a><ul>
     571               <li><a href="#rfc.section.7.1">7.1</a>&nbsp;&nbsp;&nbsp;<a href="#safe.and.idempotent">Safe and Idempotent Methods</a><ul>
     572                     <li><a href="#rfc.section.7.1.1">7.1.1</a>&nbsp;&nbsp;&nbsp;<a href="#safe.methods">Safe Methods</a></li>
     573                     <li><a href="#rfc.section.7.1.2">7.1.2</a>&nbsp;&nbsp;&nbsp;<a href="#idempotent.methods">Idempotent Methods</a></li>
    561574                  </ul>
    562575               </li>
    563                <li>7.2&nbsp;&nbsp;&nbsp;<a href="#OPTIONS">OPTIONS</a></li>
    564                <li>7.3&nbsp;&nbsp;&nbsp;<a href="#GET">GET</a></li>
    565                <li>7.4&nbsp;&nbsp;&nbsp;<a href="#HEAD">HEAD</a></li>
    566                <li>7.5&nbsp;&nbsp;&nbsp;<a href="#POST">POST</a></li>
    567                <li>7.6&nbsp;&nbsp;&nbsp;<a href="#PUT">PUT</a></li>
    568                <li>7.7&nbsp;&nbsp;&nbsp;<a href="#DELETE">DELETE</a></li>
    569                <li>7.8&nbsp;&nbsp;&nbsp;<a href="#TRACE">TRACE</a></li>
    570                <li>7.9&nbsp;&nbsp;&nbsp;<a href="#CONNECT">CONNECT</a></li>
     576               <li><a href="#rfc.section.7.2">7.2</a>&nbsp;&nbsp;&nbsp;<a href="#OPTIONS">OPTIONS</a></li>
     577               <li><a href="#rfc.section.7.3">7.3</a>&nbsp;&nbsp;&nbsp;<a href="#GET">GET</a></li>
     578               <li><a href="#rfc.section.7.4">7.4</a>&nbsp;&nbsp;&nbsp;<a href="#HEAD">HEAD</a></li>
     579               <li><a href="#rfc.section.7.5">7.5</a>&nbsp;&nbsp;&nbsp;<a href="#POST">POST</a></li>
     580               <li><a href="#rfc.section.7.6">7.6</a>&nbsp;&nbsp;&nbsp;<a href="#PUT">PUT</a></li>
     581               <li><a href="#rfc.section.7.7">7.7</a>&nbsp;&nbsp;&nbsp;<a href="#DELETE">DELETE</a></li>
     582               <li><a href="#rfc.section.7.8">7.8</a>&nbsp;&nbsp;&nbsp;<a href="#TRACE">TRACE</a></li>
     583               <li><a href="#rfc.section.7.9">7.9</a>&nbsp;&nbsp;&nbsp;<a href="#CONNECT">CONNECT</a></li>
    571584            </ul>
    572585         </li>
    573          <li>8.&nbsp;&nbsp;&nbsp;<a href="#status.codes">Status Code Definitions</a><ul>
    574                <li>8.1&nbsp;&nbsp;&nbsp;<a href="#status.1xx">Informational 1xx</a><ul>
    575                      <li>8.1.1&nbsp;&nbsp;&nbsp;<a href="#status.100">100 Continue</a></li>
    576                      <li>8.1.2&nbsp;&nbsp;&nbsp;<a href="#status.101">101 Switching Protocols</a></li>
     586         <li><a href="#rfc.section.8">8.</a>&nbsp;&nbsp;&nbsp;<a href="#status.codes">Status Code Definitions</a><ul>
     587               <li><a href="#rfc.section.8.1">8.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.1xx">Informational 1xx</a><ul>
     588                     <li><a href="#rfc.section.8.1.1">8.1.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.100">100 Continue</a></li>
     589                     <li><a href="#rfc.section.8.1.2">8.1.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.101">101 Switching Protocols</a></li>
    577590                  </ul>
    578591               </li>
    579                <li>8.2&nbsp;&nbsp;&nbsp;<a href="#status.2xx">Successful 2xx</a><ul>
    580                      <li>8.2.1&nbsp;&nbsp;&nbsp;<a href="#status.200">200 OK</a></li>
    581                      <li>8.2.2&nbsp;&nbsp;&nbsp;<a href="#status.201">201 Created</a></li>
    582                      <li>8.2.3&nbsp;&nbsp;&nbsp;<a href="#status.202">202 Accepted</a></li>
    583                      <li>8.2.4&nbsp;&nbsp;&nbsp;<a href="#status.203">203 Non-Authoritative Information</a></li>
    584                      <li>8.2.5&nbsp;&nbsp;&nbsp;<a href="#status.204">204 No Content</a></li>
    585                      <li>8.2.6&nbsp;&nbsp;&nbsp;<a href="#status.205">205 Reset Content</a></li>
    586                      <li>8.2.7&nbsp;&nbsp;&nbsp;<a href="#status.206">206 Partial Content</a></li>
     592               <li><a href="#rfc.section.8.2">8.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.2xx">Successful 2xx</a><ul>
     593                     <li><a href="#rfc.section.8.2.1">8.2.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.200">200 OK</a></li>
     594                     <li><a href="#rfc.section.8.2.2">8.2.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.201">201 Created</a></li>
     595                     <li><a href="#rfc.section.8.2.3">8.2.3</a>&nbsp;&nbsp;&nbsp;<a href="#status.202">202 Accepted</a></li>
     596                     <li><a href="#rfc.section.8.2.4">8.2.4</a>&nbsp;&nbsp;&nbsp;<a href="#status.203">203 Non-Authoritative Information</a></li>
     597                     <li><a href="#rfc.section.8.2.5">8.2.5</a>&nbsp;&nbsp;&nbsp;<a href="#status.204">204 No Content</a></li>
     598                     <li><a href="#rfc.section.8.2.6">8.2.6</a>&nbsp;&nbsp;&nbsp;<a href="#status.205">205 Reset Content</a></li>
     599                     <li><a href="#rfc.section.8.2.7">8.2.7</a>&nbsp;&nbsp;&nbsp;<a href="#status.206">206 Partial Content</a></li>
    587600                  </ul>
    588601               </li>
    589                <li>8.3&nbsp;&nbsp;&nbsp;<a href="#status.3xx">Redirection 3xx</a><ul>
    590                      <li>8.3.1&nbsp;&nbsp;&nbsp;<a href="#status.300">300 Multiple Choices</a></li>
    591                      <li>8.3.2&nbsp;&nbsp;&nbsp;<a href="#status.301">301 Moved Permanently</a></li>
    592                      <li>8.3.3&nbsp;&nbsp;&nbsp;<a href="#status.302">302 Found</a></li>
    593                      <li>8.3.4&nbsp;&nbsp;&nbsp;<a href="#status.303">303 See Other</a></li>
    594                      <li>8.3.5&nbsp;&nbsp;&nbsp;<a href="#status.304">304 Not Modified</a></li>
    595                      <li>8.3.6&nbsp;&nbsp;&nbsp;<a href="#status.305">305 Use Proxy</a></li>
    596                      <li>8.3.7&nbsp;&nbsp;&nbsp;<a href="#status.306">306 (Unused)</a></li>
    597                      <li>8.3.8&nbsp;&nbsp;&nbsp;<a href="#status.307">307 Temporary Redirect</a></li>
     602               <li><a href="#rfc.section.8.3">8.3</a>&nbsp;&nbsp;&nbsp;<a href="#status.3xx">Redirection 3xx</a><ul>
     603                     <li><a href="#rfc.section.8.3.1">8.3.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.300">300 Multiple Choices</a></li>
     604                     <li><a href="#rfc.section.8.3.2">8.3.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.301">301 Moved Permanently</a></li>
     605                     <li><a href="#rfc.section.8.3.3">8.3.3</a>&nbsp;&nbsp;&nbsp;<a href="#status.302">302 Found</a></li>
     606                     <li><a href="#rfc.section.8.3.4">8.3.4</a>&nbsp;&nbsp;&nbsp;<a href="#status.303">303 See Other</a></li>
     607                     <li><a href="#rfc.section.8.3.5">8.3.5</a>&nbsp;&nbsp;&nbsp;<a href="#status.304">304 Not Modified</a></li>
     608                     <li><a href="#rfc.section.8.3.6">8.3.6</a>&nbsp;&nbsp;&nbsp;<a href="#status.305">305 Use Proxy</a></li>
     609                     <li><a href="#rfc.section.8.3.7">8.3.7</a>&nbsp;&nbsp;&nbsp;<a href="#status.306">306 (Unused)</a></li>
     610                     <li><a href="#rfc.section.8.3.8">8.3.8</a>&nbsp;&nbsp;&nbsp;<a href="#status.307">307 Temporary Redirect</a></li>
    598611                  </ul>
    599612               </li>
    600                <li>8.4&nbsp;&nbsp;&nbsp;<a href="#status.4xx">Client Error 4xx</a><ul>
    601                      <li>8.4.1&nbsp;&nbsp;&nbsp;<a href="#status.400">400 Bad Request</a></li>
    602                      <li>8.4.2&nbsp;&nbsp;&nbsp;<a href="#status.401">401 Unauthorized</a></li>
    603                      <li>8.4.3&nbsp;&nbsp;&nbsp;<a href="#status.402">402 Payment Required</a></li>
    604                      <li>8.4.4&nbsp;&nbsp;&nbsp;<a href="#status.403">403 Forbidden</a></li>
    605                      <li>8.4.5&nbsp;&nbsp;&nbsp;<a href="#status.404">404 Not Found</a></li>
    606                      <li>8.4.6&nbsp;&nbsp;&nbsp;<a href="#status.405">405 Method Not Allowed</a></li>
    607                      <li>8.4.7&nbsp;&nbsp;&nbsp;<a href="#status.406">406 Not Acceptable</a></li>
    608                      <li>8.4.8&nbsp;&nbsp;&nbsp;<a href="#status.407">407 Proxy Authentication Required</a></li>
    609                      <li>8.4.9&nbsp;&nbsp;&nbsp;<a href="#status.408">408 Request Timeout</a></li>
    610                      <li>8.4.10&nbsp;&nbsp;&nbsp;<a href="#status.409">409 Conflict</a></li>
    611                      <li>8.4.11&nbsp;&nbsp;&nbsp;<a href="#status.410">410 Gone</a></li>
    612                      <li>8.4.12&nbsp;&nbsp;&nbsp;<a href="#status.411">411 Length Required</a></li>
    613                      <li>8.4.13&nbsp;&nbsp;&nbsp;<a href="#status.412">412 Precondition Failed</a></li>
    614                      <li>8.4.14&nbsp;&nbsp;&nbsp;<a href="#status.413">413 Request Entity Too Large</a></li>
    615                      <li>8.4.15&nbsp;&nbsp;&nbsp;<a href="#status.414">414 URI Too Long</a></li>
    616                      <li>8.4.16&nbsp;&nbsp;&nbsp;<a href="#status.415">415 Unsupported Media Type</a></li>
    617                      <li>8.4.17&nbsp;&nbsp;&nbsp;<a href="#status.416">416 Requested Range Not Satisfiable</a></li>
    618                      <li>8.4.18&nbsp;&nbsp;&nbsp;<a href="#status.417">417 Expectation Failed</a></li>
     613               <li><a href="#rfc.section.8.4">8.4</a>&nbsp;&nbsp;&nbsp;<a href="#status.4xx">Client Error 4xx</a><ul>
     614                     <li><a href="#rfc.section.8.4.1">8.4.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.400">400 Bad Request</a></li>
     615                     <li><a href="#rfc.section.8.4.2">8.4.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.401">401 Unauthorized</a></li>
     616                     <li><a href="#rfc.section.8.4.3">8.4.3</a>&nbsp;&nbsp;&nbsp;<a href="#status.402">402 Payment Required</a></li>
     617                     <li><a href="#rfc.section.8.4.4">8.4.4</a>&nbsp;&nbsp;&nbsp;<a href="#status.403">403 Forbidden</a></li>
     618                     <li><a href="#rfc.section.8.4.5">8.4.5</a>&nbsp;&nbsp;&nbsp;<a href="#status.404">404 Not Found</a></li>
     619                     <li><a href="#rfc.section.8.4.6">8.4.6</a>&nbsp;&nbsp;&nbsp;<a href="#status.405">405 Method Not Allowed</a></li>
     620                     <li><a href="#rfc.section.8.4.7">8.4.7</a>&nbsp;&nbsp;&nbsp;<a href="#status.406">406 Not Acceptable</a></li>
     621                     <li><a href="#rfc.section.8.4.8">8.4.8</a>&nbsp;&nbsp;&nbsp;<a href="#status.407">407 Proxy Authentication Required</a></li>
     622                     <li><a href="#rfc.section.8.4.9">8.4.9</a>&nbsp;&nbsp;&nbsp;<a href="#status.408">408 Request Timeout</a></li>
     623                     <li><a href="#rfc.section.8.4.10">8.4.10</a>&nbsp;&nbsp;&nbsp;<a href="#status.409">409 Conflict</a></li>
     624                     <li><a href="#rfc.section.8.4.11">8.4.11</a>&nbsp;&nbsp;&nbsp;<a href="#status.410">410 Gone</a></li>
     625                     <li><a href="#rfc.section.8.4.12">8.4.12</a>&nbsp;&nbsp;&nbsp;<a href="#status.411">411 Length Required</a></li>
     626                     <li><a href="#rfc.section.8.4.13">8.4.13</a>&nbsp;&nbsp;&nbsp;<a href="#status.412">412 Precondition Failed</a></li>
     627                     <li><a href="#rfc.section.8.4.14">8.4.14</a>&nbsp;&nbsp;&nbsp;<a href="#status.413">413 Request Entity Too Large</a></li>
     628                     <li><a href="#rfc.section.8.4.15">8.4.15</a>&nbsp;&nbsp;&nbsp;<a href="#status.414">414 URI Too Long</a></li>
     629                     <li><a href="#rfc.section.8.4.16">8.4.16</a>&nbsp;&nbsp;&nbsp;<a href="#status.415">415 Unsupported Media Type</a></li>
     630                     <li><a href="#rfc.section.8.4.17">8.4.17</a>&nbsp;&nbsp;&nbsp;<a href="#status.416">416 Requested Range Not Satisfiable</a></li>
     631                     <li><a href="#rfc.section.8.4.18">8.4.18</a>&nbsp;&nbsp;&nbsp;<a href="#status.417">417 Expectation Failed</a></li>
    619632                  </ul>
    620633               </li>
    621                <li>8.5&nbsp;&nbsp;&nbsp;<a href="#status.5xx">Server Error 5xx</a><ul>
    622                      <li>8.5.1&nbsp;&nbsp;&nbsp;<a href="#status.500">500 Internal Server Error</a></li>
    623                      <li>8.5.2&nbsp;&nbsp;&nbsp;<a href="#status.501">501 Not Implemented</a></li>
    624                      <li>8.5.3&nbsp;&nbsp;&nbsp;<a href="#status.502">502 Bad Gateway</a></li>
    625                      <li>8.5.4&nbsp;&nbsp;&nbsp;<a href="#status.503">503 Service Unavailable</a></li>
    626                      <li>8.5.5&nbsp;&nbsp;&nbsp;<a href="#status.504">504 Gateway Timeout</a></li>
    627                      <li>8.5.6&nbsp;&nbsp;&nbsp;<a href="#status.505">505 HTTP Version Not Supported</a></li>
     634               <li><a href="#rfc.section.8.5">8.5</a>&nbsp;&nbsp;&nbsp;<a href="#status.5xx">Server Error 5xx</a><ul>
     635                     <li><a href="#rfc.section.8.5.1">8.5.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.500">500 Internal Server Error</a></li>
     636                     <li><a href="#rfc.section.8.5.2">8.5.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.501">501 Not Implemented</a></li>
     637                     <li><a href="#rfc.section.8.5.3">8.5.3</a>&nbsp;&nbsp;&nbsp;<a href="#status.502">502 Bad Gateway</a></li>
     638                     <li><a href="#rfc.section.8.5.4">8.5.4</a>&nbsp;&nbsp;&nbsp;<a href="#status.503">503 Service Unavailable</a></li>
     639                     <li><a href="#rfc.section.8.5.5">8.5.5</a>&nbsp;&nbsp;&nbsp;<a href="#status.504">504 Gateway Timeout</a></li>
     640                     <li><a href="#rfc.section.8.5.6">8.5.6</a>&nbsp;&nbsp;&nbsp;<a href="#status.505">505 HTTP Version Not Supported</a></li>
    628641                  </ul>
    629642               </li>
    630643            </ul>
    631644         </li>
    632          <li>9.&nbsp;&nbsp;&nbsp;<a href="#header.fields">Header Field Definitions</a><ul>
    633                <li>9.1&nbsp;&nbsp;&nbsp;<a href="#header.allow">Allow</a></li>
    634                <li>9.2&nbsp;&nbsp;&nbsp;<a href="#header.expect">Expect</a></li>
    635                <li>9.3&nbsp;&nbsp;&nbsp;<a href="#header.from">From</a></li>
    636                <li>9.4&nbsp;&nbsp;&nbsp;<a href="#header.location">Location</a></li>
    637                <li>9.5&nbsp;&nbsp;&nbsp;<a href="#header.max-forwards">Max-Forwards</a></li>
    638                <li>9.6&nbsp;&nbsp;&nbsp;<a href="#header.referer">Referer</a></li>
    639                <li>9.7&nbsp;&nbsp;&nbsp;<a href="#header.retry-after">Retry-After</a></li>
    640                <li>9.8&nbsp;&nbsp;&nbsp;<a href="#header.server">Server</a></li>
    641                <li>9.9&nbsp;&nbsp;&nbsp;<a href="#header.user-agent">User-Agent</a></li>
     645         <li><a href="#rfc.section.9">9.</a>&nbsp;&nbsp;&nbsp;<a href="#header.fields">Header Field Definitions</a><ul>
     646               <li><a href="#rfc.section.9.1">9.1</a>&nbsp;&nbsp;&nbsp;<a href="#header.allow">Allow</a></li>
     647               <li><a href="#rfc.section.9.2">9.2</a>&nbsp;&nbsp;&nbsp;<a href="#header.expect">Expect</a></li>
     648               <li><a href="#rfc.section.9.3">9.3</a>&nbsp;&nbsp;&nbsp;<a href="#header.from">From</a></li>
     649               <li><a href="#rfc.section.9.4">9.4</a>&nbsp;&nbsp;&nbsp;<a href="#header.location">Location</a></li>
     650               <li><a href="#rfc.section.9.5">9.5</a>&nbsp;&nbsp;&nbsp;<a href="#header.max-forwards">Max-Forwards</a></li>
     651               <li><a href="#rfc.section.9.6">9.6</a>&nbsp;&nbsp;&nbsp;<a href="#header.referer">Referer</a></li>
     652               <li><a href="#rfc.section.9.7">9.7</a>&nbsp;&nbsp;&nbsp;<a href="#header.retry-after">Retry-After</a></li>
     653               <li><a href="#rfc.section.9.8">9.8</a>&nbsp;&nbsp;&nbsp;<a href="#header.server">Server</a></li>
     654               <li><a href="#rfc.section.9.9">9.9</a>&nbsp;&nbsp;&nbsp;<a href="#header.user-agent">User-Agent</a></li>
    642655            </ul>
    643656         </li>
    644          <li>10.&nbsp;&nbsp;&nbsp;<a href="#IANA.considerations">IANA Considerations</a><ul>
    645                <li>10.1&nbsp;&nbsp;&nbsp;<a href="#method.registration">Method Registry</a></li>
    646                <li>10.2&nbsp;&nbsp;&nbsp;<a href="#status.code.registration">Status Code Registry</a></li>
    647                <li>10.3&nbsp;&nbsp;&nbsp;<a href="#message.header.registration">Message Header Registration</a></li>
     657         <li><a href="#rfc.section.10">10.</a>&nbsp;&nbsp;&nbsp;<a href="#IANA.considerations">IANA Considerations</a><ul>
     658               <li><a href="#rfc.section.10.1">10.1</a>&nbsp;&nbsp;&nbsp;<a href="#method.registration">Method Registry</a></li>
     659               <li><a href="#rfc.section.10.2">10.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.code.registration">Status Code Registry</a></li>
     660               <li><a href="#rfc.section.10.3">10.3</a>&nbsp;&nbsp;&nbsp;<a href="#message.header.registration">Message Header Registration</a></li>
    648661            </ul>
    649662         </li>
    650          <li>11.&nbsp;&nbsp;&nbsp;<a href="#security.considerations">Security Considerations</a><ul>
    651                <li>11.1&nbsp;&nbsp;&nbsp;<a href="#security.sensitive">Transfer of Sensitive Information</a></li>
    652                <li>11.2&nbsp;&nbsp;&nbsp;<a href="#encoding.sensitive.information.in.uris">Encoding Sensitive Information in URIs</a></li>
    653                <li>11.3&nbsp;&nbsp;&nbsp;<a href="#location.spoofing">Location Headers and Spoofing</a></li>
     663         <li><a href="#rfc.section.11">11.</a>&nbsp;&nbsp;&nbsp;<a href="#security.considerations">Security Considerations</a><ul>
     664               <li><a href="#rfc.section.11.1">11.1</a>&nbsp;&nbsp;&nbsp;<a href="#security.sensitive">Transfer of Sensitive Information</a></li>
     665               <li><a href="#rfc.section.11.2">11.2</a>&nbsp;&nbsp;&nbsp;<a href="#encoding.sensitive.information.in.uris">Encoding Sensitive Information in URIs</a></li>
     666               <li><a href="#rfc.section.11.3">11.3</a>&nbsp;&nbsp;&nbsp;<a href="#location.spoofing">Location Headers and Spoofing</a></li>
    654667            </ul>
    655668         </li>
    656          <li>12.&nbsp;&nbsp;&nbsp;<a href="#ack">Acknowledgments</a></li>
    657          <li>13.&nbsp;&nbsp;&nbsp;<a href="#rfc.references">References</a><ul>
    658                <li>13.1&nbsp;&nbsp;&nbsp;<a href="#rfc.references.1">Normative References</a></li>
    659                <li>13.2&nbsp;&nbsp;&nbsp;<a href="#rfc.references.2">Informative References</a></li>
     669         <li><a href="#rfc.section.12">12.</a>&nbsp;&nbsp;&nbsp;<a href="#ack">Acknowledgments</a></li>
     670         <li><a href="#rfc.section.13">13.</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references">References</a><ul>
     671               <li><a href="#rfc.section.13.1">13.1</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.1">Normative References</a></li>
     672               <li><a href="#rfc.section.13.2">13.2</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.2">Informative References</a></li>
    660673            </ul>
    661674         </li>
    662          <li><a href="#rfc.authors">Authors' Addresses</a></li>
    663          <li>A.&nbsp;&nbsp;&nbsp;<a href="#compatibility">Compatibility with Previous Versions</a><ul>
    664                <li>A.1&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc.2068">Changes from RFC 2068</a></li>
    665                <li>A.2&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc.2616">Changes from RFC 2616</a></li>
     675         <li><a href="#rfc.section.A">A.</a>&nbsp;&nbsp;&nbsp;<a href="#compatibility">Compatibility with Previous Versions</a><ul>
     676               <li><a href="#rfc.section.A.1">A.1</a>&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc.2068">Changes from RFC 2068</a></li>
     677               <li><a href="#rfc.section.A.2">A.2</a>&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc.2616">Changes from RFC 2616</a></li>
    666678            </ul>
    667679         </li>
    668          <li>B.&nbsp;&nbsp;&nbsp;<a href="#collected.abnf">Collected ABNF</a></li>
    669          <li>C.&nbsp;&nbsp;&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a><ul>
    670                <li>C.1&nbsp;&nbsp;&nbsp;<a href="#rfc.section.C.1">Since RFC2616</a></li>
    671                <li>C.2&nbsp;&nbsp;&nbsp;<a href="#rfc.section.C.2">Since draft-ietf-httpbis-p2-semantics-00</a></li>
    672                <li>C.3&nbsp;&nbsp;&nbsp;<a href="#rfc.section.C.3">Since draft-ietf-httpbis-p2-semantics-01</a></li>
    673                <li>C.4&nbsp;&nbsp;&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-p2-semantics-02</a></li>
    674                <li>C.5&nbsp;&nbsp;&nbsp;<a href="#changes.since.03">Since draft-ietf-httpbis-p2-semantics-03</a></li>
    675                <li>C.6&nbsp;&nbsp;&nbsp;<a href="#changes.since.04">Since draft-ietf-httpbis-p2-semantics-04</a></li>
    676                <li>C.7&nbsp;&nbsp;&nbsp;<a href="#changes.since.05">Since draft-ietf-httpbis-p2-semantics-05</a></li>
    677                <li>C.8&nbsp;&nbsp;&nbsp;<a href="#changes.since.06">Since draft-ietf-httpbis-p2-semantics-06</a></li>
    678                <li>C.9&nbsp;&nbsp;&nbsp;<a href="#changes.since.07">Since draft-ietf-httpbis-p2-semantics-07</a></li>
    679                <li>C.10&nbsp;&nbsp;&nbsp;<a href="#changes.since.08">Since draft-ietf-httpbis-p2-semantics-08</a></li>
    680                <li>C.11&nbsp;&nbsp;&nbsp;<a href="#changes.since.09">Since draft-ietf-httpbis-p2-semantics-09</a></li>
     680         <li><a href="#rfc.section.B">B.</a>&nbsp;&nbsp;&nbsp;<a href="#collected.abnf">Collected ABNF</a></li>
     681         <li><a href="#rfc.section.C">C.</a>&nbsp;&nbsp;&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a><ul>
     682               <li><a href="#rfc.section.C.1">C.1</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.section.C.1">Since RFC2616</a></li>
     683               <li><a href="#rfc.section.C.2">C.2</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.section.C.2">Since draft-ietf-httpbis-p2-semantics-00</a></li>
     684               <li><a href="#rfc.section.C.3">C.3</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.section.C.3">Since draft-ietf-httpbis-p2-semantics-01</a></li>
     685               <li><a href="#rfc.section.C.4">C.4</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-p2-semantics-02</a></li>
     686               <li><a href="#rfc.section.C.5">C.5</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.03">Since draft-ietf-httpbis-p2-semantics-03</a></li>
     687               <li><a href="#rfc.section.C.6">C.6</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.04">Since draft-ietf-httpbis-p2-semantics-04</a></li>
     688               <li><a href="#rfc.section.C.7">C.7</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.05">Since draft-ietf-httpbis-p2-semantics-05</a></li>
     689               <li><a href="#rfc.section.C.8">C.8</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.06">Since draft-ietf-httpbis-p2-semantics-06</a></li>
     690               <li><a href="#rfc.section.C.9">C.9</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.07">Since draft-ietf-httpbis-p2-semantics-07</a></li>
     691               <li><a href="#rfc.section.C.10">C.10</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.08">Since draft-ietf-httpbis-p2-semantics-08</a></li>
     692               <li><a href="#rfc.section.C.11">C.11</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.09">Since draft-ietf-httpbis-p2-semantics-09</a></li>
    681693            </ul>
    682694         </li>
    683695         <li><a href="#rfc.index">Index</a></li>
     696         <li><a href="#rfc.authors">Authors' Addresses</a></li>
    684697      </ul>
    685       <h1 id="rfc.section.1" class="np"><a href="#rfc.section.1">1.</a>&nbsp;<a id="introduction" href="#introduction">Introduction</a></h1>
    686       <p id="rfc.section.1.p.1">This document defines HTTP/1.1 request and response semantics. Each HTTP message, as defined in <a href="#Part1" id="rfc.xref.Part1.1"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, is in the form of either a request or a response. An HTTP server listens on a connection for HTTP requests and responds
    687          to each request, in the order received on that connection, with one or more HTTP response messages. This document defines
    688          the commonly agreed upon semantics of the HTTP uniform interface, the intentions defined by each request method, and the various
    689          response messages that might be expected as a result of applying that method for the requested resource.
    690       </p>
    691       <p id="rfc.section.1.p.2">This document is currently disorganized in order to minimize the changes between drafts and enable reviewers to see the smaller
    692          errata changes. The next draft will reorganize the sections to better reflect the content. In particular, the sections will
    693          be ordered according to the typical processing of an HTTP request message (after message parsing): resource mapping, general
    694          header fields, methods, request modifiers, response status, and resource metadata. The current mess reflects how widely dispersed
    695          these topics and associated requirements had become in <a href="#RFC2616" id="rfc.xref.RFC2616.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>.
    696       </p>
    697       <h2 id="rfc.section.1.1"><a href="#rfc.section.1.1">1.1</a>&nbsp;<a id="intro.requirements" href="#intro.requirements">Requirements</a></h2>
    698       <p id="rfc.section.1.1.p.1">The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
    699          in this document are to be interpreted as described in <a href="#RFC2119" id="rfc.xref.RFC2119.1"><cite title="Key words for use in RFCs to Indicate Requirement Levels">[RFC2119]</cite></a>.
    700       </p>
    701       <p id="rfc.section.1.1.p.2">An implementation is not compliant if it fails to satisfy one or more of the "MUST" or "REQUIRED" level requirements for the
    702          protocols it implements. An implementation that satisfies all the "MUST" or "REQUIRED" level and all the "SHOULD" level requirements
    703          for its protocols is said to be "unconditionally compliant"; one that satisfies all the "MUST" level requirements but not
    704          all the "SHOULD" level requirements for its protocols is said to be "conditionally compliant".
    705       </p>
    706       <h2 id="rfc.section.1.2"><a href="#rfc.section.1.2">1.2</a>&nbsp;<a id="notation" href="#notation">Syntax Notation</a></h2>
    707       <p id="rfc.section.1.2.p.1">This specification uses the ABNF syntax defined in <a href="p1-messaging.html#notation" title="Syntax Notation">Section 1.2</a> of <a href="#Part1" id="rfc.xref.Part1.2"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a> (which extends the syntax defined in <a href="#RFC5234" id="rfc.xref.RFC5234.1"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a> with a list rule). <a href="#collected.abnf" title="Collected ABNF">Appendix&nbsp;B</a> shows the collected ABNF, with the list rule expanded.
    708       </p>
    709       <p id="rfc.section.1.2.p.2">The following core rules are included by reference, as defined in <a href="#RFC5234" id="rfc.xref.RFC5234.2"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a>, <a href="http://tools.ietf.org/html/rfc5234#appendix-B.1">Appendix B.1</a>: ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote), HEXDIG
    710          (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit sequence of data), SP (space), VCHAR (any visible USASCII character),
    711          and WSP (whitespace).
    712       </p>
    713       <h3 id="rfc.section.1.2.1"><a href="#rfc.section.1.2.1">1.2.1</a>&nbsp;<a id="core.rules" href="#core.rules">Core Rules</a></h3>
    714       <p id="rfc.section.1.2.1.p.1">The core rules below are defined in <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a> of <a href="#Part1" id="rfc.xref.Part1.3"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>:
    715       </p>
    716       <div id="rfc.figure.u.1"></div><pre class="inline">  <a href="#core.rules" class="smpl">quoted-string</a> = &lt;quoted-string, defined in <a href="#Part1" id="rfc.xref.Part1.4"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a>&gt;
     698      <div id="introduction">
     699         <h1 id="rfc.section.1" class="np"><a href="#rfc.section.1">1.</a>&nbsp;<a href="#introduction">Introduction</a></h1>
     700         <p id="rfc.section.1.p.1">This document defines HTTP/1.1 request and response semantics. Each HTTP message, as defined in <a href="#Part1" id="rfc.xref.Part1.1"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, is in the form of either a request or a response. An HTTP server listens on a connection for HTTP requests and responds
     701            to each request, in the order received on that connection, with one or more HTTP response messages. This document defines
     702            the commonly agreed upon semantics of the HTTP uniform interface, the intentions defined by each request method, and the various
     703            response messages that might be expected as a result of applying that method for the requested resource.
     704         </p>
     705         <p id="rfc.section.1.p.2">This document is currently disorganized in order to minimize the changes between drafts and enable reviewers to see the smaller
     706            errata changes. The next draft will reorganize the sections to better reflect the content. In particular, the sections will
     707            be ordered according to the typical processing of an HTTP request message (after message parsing): resource mapping, general
     708            header fields, methods, request modifiers, response status, and resource metadata. The current mess reflects how widely dispersed
     709            these topics and associated requirements had become in <a href="#RFC2616" id="rfc.xref.RFC2616.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>.
     710         </p>
     711         <div id="intro.requirements">
     712            <h2 id="rfc.section.1.1"><a href="#rfc.section.1.1">1.1</a>&nbsp;<a href="#intro.requirements">Requirements</a></h2>
     713            <p id="rfc.section.1.1.p.1">The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
     714               in this document are to be interpreted as described in <a href="#RFC2119" id="rfc.xref.RFC2119.1"><cite title="Key words for use in RFCs to Indicate Requirement Levels">[RFC2119]</cite></a>.
     715            </p>
     716            <p id="rfc.section.1.1.p.2">An implementation is not compliant if it fails to satisfy one or more of the "MUST" or "REQUIRED" level requirements for the
     717               protocols it implements. An implementation that satisfies all the "MUST" or "REQUIRED" level and all the "SHOULD" level requirements
     718               for its protocols is said to be "unconditionally compliant"; one that satisfies all the "MUST" level requirements but not
     719               all the "SHOULD" level requirements for its protocols is said to be "conditionally compliant".
     720            </p>
     721         </div>
     722         <div id="notation">
     723            <h2 id="rfc.section.1.2"><a href="#rfc.section.1.2">1.2</a>&nbsp;<a href="#notation">Syntax Notation</a></h2>
     724            <p id="rfc.section.1.2.p.1">This specification uses the ABNF syntax defined in <a href="p1-messaging.html#notation" title="Syntax Notation">Section 1.2</a> of <a href="#Part1" id="rfc.xref.Part1.2"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a> (which extends the syntax defined in <a href="#RFC5234" id="rfc.xref.RFC5234.1"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a> with a list rule). <a href="#collected.abnf" title="Collected ABNF">Appendix&nbsp;B</a> shows the collected ABNF, with the list rule expanded.
     725            </p>
     726            <p id="rfc.section.1.2.p.2">The following core rules are included by reference, as defined in <a href="#RFC5234" id="rfc.xref.RFC5234.2"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a>, <a href="https://tools.ietf.org/html/rfc5234#appendix-B.1">Appendix B.1</a>: ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote), HEXDIG
     727               (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit sequence of data), SP (space), VCHAR (any visible USASCII character),
     728               and WSP (whitespace).
     729            </p>
     730            <div id="core.rules">
     731               <h3 id="rfc.section.1.2.1"><a href="#rfc.section.1.2.1">1.2.1</a>&nbsp;<a href="#core.rules">Core Rules</a></h3>
     732               <p id="rfc.section.1.2.1.p.1">The core rules below are defined in <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a> of <a href="#Part1" id="rfc.xref.Part1.3"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>:
     733               </p>
     734               <div id="rfc.figure.u.1"></div><pre class="inline">  <a href="#core.rules" class="smpl">quoted-string</a> = &lt;quoted-string, defined in <a href="#Part1" id="rfc.xref.Part1.4"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a>&gt;
    717735  <a href="#core.rules" class="smpl">token</a>         = &lt;token, defined in <a href="#Part1" id="rfc.xref.Part1.5"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a>&gt;
    718736  <a href="#core.rules" class="smpl">OWS</a>           = &lt;OWS, defined in <a href="#Part1" id="rfc.xref.Part1.6"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a>&gt;
    719737  <a href="#core.rules" class="smpl">RWS</a>           = &lt;RWS, defined in <a href="#Part1" id="rfc.xref.Part1.7"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a>&gt;
    720738  <a href="#core.rules" class="smpl">obs-text</a>      = &lt;obs-text, defined in <a href="#Part1" id="rfc.xref.Part1.8"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a>&gt;
    721 </pre><h3 id="rfc.section.1.2.2"><a href="#rfc.section.1.2.2">1.2.2</a>&nbsp;<a id="abnf.dependencies" href="#abnf.dependencies">ABNF Rules defined in other Parts of the Specification</a></h3>
    722       <p id="rfc.section.1.2.2.p.1">The ABNF rules below are defined in other parts:</p>
    723       <div id="rfc.figure.u.2"></div><pre class="inline">  <a href="#abnf.dependencies" class="smpl">absolute-URI</a>  = &lt;absolute-URI, defined in <a href="#Part1" id="rfc.xref.Part1.9"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#uri" title="Uniform Resource Identifiers">Section 2.6</a>&gt;
     739</pre></div>
     740            <div id="abnf.dependencies">
     741               <h3 id="rfc.section.1.2.2"><a href="#rfc.section.1.2.2">1.2.2</a>&nbsp;<a href="#abnf.dependencies">ABNF Rules defined in other Parts of the Specification</a></h3>
     742               <p id="rfc.section.1.2.2.p.1">The ABNF rules below are defined in other parts:</p>
     743               <div id="rfc.figure.u.2"></div><pre class="inline">  <a href="#abnf.dependencies" class="smpl">absolute-URI</a>  = &lt;absolute-URI, defined in <a href="#Part1" id="rfc.xref.Part1.9"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#uri" title="Uniform Resource Identifiers">Section 2.6</a>&gt;
    724744  <a href="#abnf.dependencies" class="smpl">comment</a>       = &lt;comment, defined in <a href="#Part1" id="rfc.xref.Part1.10"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#header.fields" title="Header Fields">Section 3.2</a>&gt;
    725745  <a href="#abnf.dependencies" class="smpl">Host</a>          = &lt;Host, defined in <a href="#Part1" id="rfc.xref.Part1.11"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#uri" title="Uniform Resource Identifiers">Section 2.6</a>&gt;
    … …  
    755775  <a href="#abnf.dependencies" class="smpl">WWW-Authenticate</a> =
    756776             &lt;WWW-Authenticate, defined in <a href="#Part7" id="rfc.xref.Part7.4"><cite title="HTTP/1.1, part 7: Authentication">[Part7]</cite></a>, <a href="p7-auth.html#header.www-authenticate" title="WWW-Authenticate">Section 3.4</a>&gt;
    757 </pre><h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a id="method" href="#method">Method</a></h1>
    758       <p id="rfc.section.2.p.1">The Method token indicates the method to be performed on the resource identified by the Effective Request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 4.3</a> of <a href="#Part1" id="rfc.xref.Part1.17"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). The method is case-sensitive.
    759       </p>
    760       <div id="rfc.figure.u.8"></div><pre class="inline"><span id="rfc.iref.g.1"></span><span id="rfc.iref.g.2"></span>  <a href="#method" class="smpl">Method</a>         = %x4F.50.54.49.4F.4E.53   ; "OPTIONS", <a href="#OPTIONS" id="rfc.xref.OPTIONS.1" title="OPTIONS">Section&nbsp;7.2</a>
     777</pre></div>
     778         </div>
     779      </div>
     780      <div id="method">
     781         <h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a href="#method">Method</a></h1>
     782         <p id="rfc.section.2.p.1">The Method token indicates the method to be performed on the resource identified by the Effective Request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 4.3</a> of <a href="#Part1" id="rfc.xref.Part1.17"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). The method is case-sensitive.
     783         </p>
     784         <div id="rfc.figure.u.8"></div><pre class="inline"><span id="rfc.iref.g.1"></span><span id="rfc.iref.g.2"></span>  <a href="#method" class="smpl">Method</a>         = %x4F.50.54.49.4F.4E.53   ; "OPTIONS", <a href="#OPTIONS" id="rfc.xref.OPTIONS.1" title="OPTIONS">Section&nbsp;7.2</a>
    761785                 / %x47.45.54               ; "GET", <a href="#GET" id="rfc.xref.GET.1" title="GET">Section&nbsp;7.3</a>
    762786                 / %x48.45.41.44            ; "HEAD", <a href="#HEAD" id="rfc.xref.HEAD.1" title="HEAD">Section&nbsp;7.4</a>
    … …  
    769793  <a href="#method" class="smpl">extension-method</a> = <a href="#core.rules" class="smpl">token</a>
    770794</pre><p id="rfc.section.2.p.3">The list of methods allowed by a resource can be specified in an Allow header field (<a href="#header.allow" id="rfc.xref.header.allow.1" title="Allow">Section&nbsp;9.1</a>). The return code of the response always notifies the client whether a method is currently allowed on a resource, since the
    771          set of allowed methods can change dynamically. An origin server <em class="bcp14">SHOULD</em> return the status code 405 (Method Not Allowed) if the method is known by the origin server but not allowed for the requested
    772          resource, and 501 (Not Implemented) if the method is unrecognized or not implemented by the origin server. The methods GET
    773          and HEAD <em class="bcp14">MUST</em> be supported by all general-purpose servers. All other methods are <em class="bcp14">OPTIONAL</em>; however, if the above methods are implemented, they <em class="bcp14">MUST</em> be implemented with the same semantics as those specified in <a href="#method.definitions" title="Method Definitions">Section&nbsp;7</a>.
    774       </p>
    775       <h2 id="rfc.section.2.1"><a href="#rfc.section.2.1">2.1</a>&nbsp;<a id="method.registry" href="#method.registry">Method Registry</a></h2>
    776       <p id="rfc.section.2.1.p.1">The HTTP Method Registry defines the name space for the Method token in the Request line of an HTTP request.</p>
    777       <p id="rfc.section.2.1.p.2">Registrations <em class="bcp14">MUST</em> include the following fields:
    778       </p>
    779       <ul>
    780          <li>Method Name (see <a href="#method" title="Method">Section&nbsp;2</a>)
    781          </li>
    782          <li>Safe ("yes" or "no", see <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>)
    783          </li>
    784          <li>Pointer to specification text</li>
    785       </ul>
    786       <p id="rfc.section.2.1.p.3">Values to be added to this name space are subject to IETF review (<a href="#RFC5226" id="rfc.xref.RFC5226.1"><cite title="Guidelines for Writing an IANA Considerations Section in RFCs">[RFC5226]</cite></a>, <a href="http://tools.ietf.org/html/rfc5226#section-4.1">Section 4.1</a>).
    787       </p>
    788       <p id="rfc.section.2.1.p.4">The registry itself is maintained at &lt;<a href="http://www.iana.org/assignments/http-methods">http://www.iana.org/assignments/http-methods</a>&gt;.
    789       </p>
    790       <h1 id="rfc.section.3"><a href="#rfc.section.3">3.</a>&nbsp;<a id="request.header.fields" href="#request.header.fields">Request Header Fields</a></h1>
    791       <p id="rfc.section.3.p.1">The request-header fields allow the client to pass additional information about the request, and about the client itself,
    792          to the server. These fields act as request modifiers, with semantics equivalent to the parameters on a programming language
    793          method invocation.
    794       </p>
    795       <div id="rfc.figure.u.9"></div><pre class="inline"><span id="rfc.iref.g.3"></span>  <a href="#request.header.fields" class="smpl">request-header</a> = <a href="#abnf.dependencies" class="smpl">Accept</a>                   ; <a href="#Part3" id="rfc.xref.Part3.5"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>, <a href="p3-payload.html#header.accept" title="Accept">Section 5.1</a>
     795            set of allowed methods can change dynamically. An origin server <em class="bcp14">SHOULD</em> return the status code 405 (Method Not Allowed) if the method is known by the origin server but not allowed for the requested
     796            resource, and 501 (Not Implemented) if the method is unrecognized or not implemented by the origin server. The methods GET
     797            and HEAD <em class="bcp14">MUST</em> be supported by all general-purpose servers. All other methods are <em class="bcp14">OPTIONAL</em>; however, if the above methods are implemented, they <em class="bcp14">MUST</em> be implemented with the same semantics as those specified in <a href="#method.definitions" title="Method Definitions">Section&nbsp;7</a>.
     798         </p>
     799         <div id="method.registry">
     800            <h2 id="rfc.section.2.1"><a href="#rfc.section.2.1">2.1</a>&nbsp;<a href="#method.registry">Method Registry</a></h2>
     801            <p id="rfc.section.2.1.p.1">The HTTP Method Registry defines the name space for the Method token in the Request line of an HTTP request.</p>
     802            <p id="rfc.section.2.1.p.2">Registrations <em class="bcp14">MUST</em> include the following fields:
     803            </p>
     804            <ul>
     805               <li>Method Name (see <a href="#method" title="Method">Section&nbsp;2</a>)
     806               </li>
     807               <li>Safe ("yes" or "no", see <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>)
     808               </li>
     809               <li>Pointer to specification text</li>
     810            </ul>
     811            <p id="rfc.section.2.1.p.3">Values to be added to this name space are subject to IETF review (<a href="#RFC5226" id="rfc.xref.RFC5226.1"><cite title="Guidelines for Writing an IANA Considerations Section in RFCs">[RFC5226]</cite></a>, <a href="https://tools.ietf.org/html/rfc5226#section-4.1">Section 4.1</a>).
     812            </p>
     813            <p id="rfc.section.2.1.p.4">The registry itself is maintained at &lt;<a href="http://www.iana.org/assignments/http-methods">http://www.iana.org/assignments/http-methods</a>&gt;.
     814            </p>
     815         </div>
     816      </div>
     817      <div id="request.header.fields">
     818         <h1 id="rfc.section.3"><a href="#rfc.section.3">3.</a>&nbsp;<a href="#request.header.fields">Request Header Fields</a></h1>
     819         <p id="rfc.section.3.p.1">The request-header fields allow the client to pass additional information about the request, and about the client itself,
     820            to the server. These fields act as request modifiers, with semantics equivalent to the parameters on a programming language
     821            method invocation.
     822         </p>
     823         <div id="rfc.figure.u.9"></div><pre class="inline"><span id="rfc.iref.g.3"></span>  <a href="#request.header.fields" class="smpl">request-header</a> = <a href="#abnf.dependencies" class="smpl">Accept</a>                   ; <a href="#Part3" id="rfc.xref.Part3.5"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>, <a href="p3-payload.html#header.accept" title="Accept">Section 5.1</a>
    796824                 / <a href="#abnf.dependencies" class="smpl">Accept-Charset</a>           ; <a href="#Part3" id="rfc.xref.Part3.6"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>, <a href="p3-payload.html#header.accept-charset" title="Accept-Charset">Section 5.2</a>
    797825                 / <a href="#abnf.dependencies" class="smpl">Accept-Encoding</a>          ; <a href="#Part3" id="rfc.xref.Part3.7"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>, <a href="p3-payload.html#header.accept-encoding" title="Accept-Encoding">Section 5.3</a>
    … …  
    813841                 / <a href="#header.user-agent" class="smpl">User-Agent</a>               ; <a href="#header.user-agent" id="rfc.xref.header.user-agent.1" title="User-Agent">Section&nbsp;9.9</a>
    814842</pre><p id="rfc.section.3.p.3">Request-header field names can be extended reliably only in combination with a change in the protocol version. However, new
    815          or experimental header fields <em class="bcp14">MAY</em> be given the semantics of request-header fields if all parties in the communication recognize them to be request-header fields.
    816          Unrecognized header fields are treated as entity-header fields.
    817       </p>
    818       <h1 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a id="status.code.and.reason.phrase" href="#status.code.and.reason.phrase">Status Code and Reason Phrase</a></h1>
    819       <p id="rfc.section.4.p.1">The Status-Code element is a 3-digit integer result code of the attempt to understand and satisfy the request. The status
    820          codes listed below are defined in <a href="#status.codes" title="Status Code Definitions">Section&nbsp;8</a>, <a href="p4-conditional.html#status.code.definitions" title="Status Code Definitions">Section 3</a> of <a href="#Part4" id="rfc.xref.Part4.10"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>, <a href="p5-range.html#status.code.definitions" title="Status Code Definitions">Section 3</a> of <a href="#Part5" id="rfc.xref.Part5.6"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>, and <a href="p7-auth.html#status.code.definitions" title="Status Code Definitions">Section 2</a> of <a href="#Part7" id="rfc.xref.Part7.7"><cite title="HTTP/1.1, part 7: Authentication">[Part7]</cite></a>.
    821       </p>
    822       <p id="rfc.section.4.p.2">The Reason-Phrase is intended to give a short textual description of the Status-Code. The Status-Code is intended for use
    823          by automata and the Reason-Phrase is intended for the human user. The client is not required to examine or display the Reason-Phrase.
    824       </p>
    825       <p id="rfc.section.4.p.3">The individual values of the numeric status codes defined for HTTP/1.1, and an example set of corresponding Reason-Phrase
    826          values, are presented below. The reason phrases listed here are only recommendations -- they <em class="bcp14">MAY</em> be replaced by local equivalents without affecting the protocol.
    827       </p>
    828       <div id="rfc.figure.u.10"></div><pre class="inline"><span id="rfc.iref.g.4"></span><span id="rfc.iref.g.5"></span><span id="rfc.iref.g.6"></span>  <a href="#status.code.and.reason.phrase" class="smpl">Status-Code</a> =
     843            or experimental header fields <em class="bcp14">MAY</em> be given the semantics of request-header fields if all parties in the communication recognize them to be request-header fields.
     844            Unrecognized header fields are treated as entity-header fields.
     845         </p>
     846      </div>
     847      <div id="status.code.and.reason.phrase">
     848         <h1 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a href="#status.code.and.reason.phrase">Status Code and Reason Phrase</a></h1>
     849         <p id="rfc.section.4.p.1">The Status-Code element is a 3-digit integer result code of the attempt to understand and satisfy the request. The status
     850            codes listed below are defined in <a href="#status.codes" title="Status Code Definitions">Section&nbsp;8</a>, <a href="p4-conditional.html#status.code.definitions" title="Status Code Definitions">Section 3</a> of <a href="#Part4" id="rfc.xref.Part4.10"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>, <a href="p5-range.html#status.code.definitions" title="Status Code Definitions">Section 3</a> of <a href="#Part5" id="rfc.xref.Part5.6"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>, and <a href="p7-auth.html#status.code.definitions" title="Status Code Definitions">Section 2</a> of <a href="#Part7" id="rfc.xref.Part7.7"><cite title="HTTP/1.1, part 7: Authentication">[Part7]</cite></a>.
     851         </p>
     852         <p id="rfc.section.4.p.2">The Reason-Phrase is intended to give a short textual description of the Status-Code. The Status-Code is intended for use
     853            by automata and the Reason-Phrase is intended for the human user. The client is not required to examine or display the Reason-Phrase.
     854         </p>
     855         <p id="rfc.section.4.p.3">The individual values of the numeric status codes defined for HTTP/1.1, and an example set of corresponding Reason-Phrase
     856            values, are presented below. The reason phrases listed here are only recommendations -- they <em class="bcp14">MAY</em> be replaced by local equivalents without affecting the protocol.
     857         </p>
     858         <div id="rfc.figure.u.10"></div><pre class="inline"><span id="rfc.iref.g.4"></span><span id="rfc.iref.g.5"></span><span id="rfc.iref.g.6"></span>  <a href="#status.code.and.reason.phrase" class="smpl">Status-Code</a> =
    829859       "100"  ; <a href="#status.100" id="rfc.xref.status.100.1" title="100 Continue">Section&nbsp;8.1.1</a>: Continue
    830860     / "101"  ; <a href="#status.101" id="rfc.xref.status.101.1" title="101 Switching Protocols">Section&nbsp;8.1.2</a>: Switching Protocols
    … …  
    872902  <a href="#status.code.and.reason.phrase" class="smpl">Reason-Phrase</a>  = *( <a href="#notation" class="smpl">WSP</a> / <a href="#notation" class="smpl">VCHAR</a> / <a href="#core.rules" class="smpl">obs-text</a> )
    873903</pre><p id="rfc.section.4.p.5">HTTP status codes are extensible. HTTP applications are not required to understand the meaning of all registered status codes,
    874          though such understanding is obviously desirable. However, applications <em class="bcp14">MUST</em> understand the class of any status code, as indicated by the first digit, and treat any unrecognized response as being equivalent
    875          to the x00 status code of that class, with the exception that an unrecognized response <em class="bcp14">MUST NOT</em> be cached. For example, if an unrecognized status code of 431 is received by the client, it can safely assume that there was
    876          something wrong with its request and treat the response as if it had received a 400 status code. In such cases, user agents <em class="bcp14">SHOULD</em> present to the user the entity returned with the response, since that entity is likely to include human-readable information
    877          which will explain the unusual status.
    878       </p>
    879       <h2 id="rfc.section.4.1"><a href="#rfc.section.4.1">4.1</a>&nbsp;<a id="status.code.registry" href="#status.code.registry">Status Code Registry</a></h2>
    880       <p id="rfc.section.4.1.p.1">The HTTP Status Code Registry defines the name space for the Status-Code token in the Status line of an HTTP response.</p>
    881       <p id="rfc.section.4.1.p.2">Values to be added to this name space are subject to IETF review (<a href="#RFC5226" id="rfc.xref.RFC5226.2"><cite title="Guidelines for Writing an IANA Considerations Section in RFCs">[RFC5226]</cite></a>, <a href="http://tools.ietf.org/html/rfc5226#section-4.1">Section 4.1</a>).
    882       </p>
    883       <p id="rfc.section.4.1.p.3">The registry itself is maintained at &lt;<a href="http://www.iana.org/assignments/http-status-codes">http://www.iana.org/assignments/http-status-codes</a>&gt;.
    884       </p>
    885       <h1 id="rfc.section.5"><a href="#rfc.section.5">5.</a>&nbsp;<a id="response.header.fields" href="#response.header.fields">Response Header Fields</a></h1>
    886       <p id="rfc.section.5.p.1">The response-header fields allow the server to pass additional information about the response which cannot be placed in the
    887          Status-Line. These header fields give information about the server and about further access to the resource identified by
    888          the Effective Request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 4.3</a> of <a href="#Part1" id="rfc.xref.Part1.20"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>).
    889       </p>
    890       <div id="rfc.figure.u.11"></div><pre class="inline"><span id="rfc.iref.g.7"></span>  <a href="#response.header.fields" class="smpl">response-header</a> = <a href="#abnf.dependencies" class="smpl">Accept-Ranges</a>           ; <a href="#Part5" id="rfc.xref.Part5.9"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>, <a href="p5-range.html#header.accept-ranges" title="Accept-Ranges">Section 5.1</a>
     904            though such understanding is obviously desirable. However, applications <em class="bcp14">MUST</em> understand the class of any status code, as indicated by the first digit, and treat any unrecognized response as being equivalent
     905            to the x00 status code of that class, with the exception that an unrecognized response <em class="bcp14">MUST NOT</em> be cached. For example, if an unrecognized status code of 431 is received by the client, it can safely assume that there was
     906            something wrong with its request and treat the response as if it had received a 400 status code. In such cases, user agents <em class="bcp14">SHOULD</em> present to the user the entity returned with the response, since that entity is likely to include human-readable information
     907            which will explain the unusual status.
     908         </p>
     909         <div id="status.code.registry">
     910            <h2 id="rfc.section.4.1"><a href="#rfc.section.4.1">4.1</a>&nbsp;<a href="#status.code.registry">Status Code Registry</a></h2>
     911            <p id="rfc.section.4.1.p.1">The HTTP Status Code Registry defines the name space for the Status-Code token in the Status line of an HTTP response.</p>
     912            <p id="rfc.section.4.1.p.2">Values to be added to this name space are subject to IETF review (<a href="#RFC5226" id="rfc.xref.RFC5226.2"><cite title="Guidelines for Writing an IANA Considerations Section in RFCs">[RFC5226]</cite></a>, <a href="https://tools.ietf.org/html/rfc5226#section-4.1">Section 4.1</a>).
     913            </p>
     914            <p id="rfc.section.4.1.p.3">The registry itself is maintained at &lt;<a href="http://www.iana.org/assignments/http-status-codes">http://www.iana.org/assignments/http-status-codes</a>&gt;.
     915            </p>
     916         </div>
     917      </div>
     918      <div id="response.header.fields">
     919         <h1 id="rfc.section.5"><a href="#rfc.section.5">5.</a>&nbsp;<a href="#response.header.fields">Response Header Fields</a></h1>
     920         <p id="rfc.section.5.p.1">The response-header fields allow the server to pass additional information about the response which cannot be placed in the
     921            Status-Line. These header fields give information about the server and about further access to the resource identified by
     922            the Effective Request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 4.3</a> of <a href="#Part1" id="rfc.xref.Part1.20"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>).
     923         </p>
     924         <div id="rfc.figure.u.11"></div><pre class="inline"><span id="rfc.iref.g.7"></span>  <a href="#response.header.fields" class="smpl">response-header</a> = <a href="#abnf.dependencies" class="smpl">Accept-Ranges</a>           ; <a href="#Part5" id="rfc.xref.Part5.9"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>, <a href="p5-range.html#header.accept-ranges" title="Accept-Ranges">Section 5.1</a>
    891925                  / <a href="#abnf.dependencies" class="smpl">Age</a>                     ; <a href="#Part6" id="rfc.xref.Part6.3"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a>, <a href="p6-cache.html#header.age" title="Age">Section 3.1</a>
    892926                  / <a href="#header.allow" class="smpl">Allow</a>                   ; <a href="#header.allow" id="rfc.xref.header.allow.2" title="Allow">Section&nbsp;9.1</a>
    … …  
    899933                  / <a href="#abnf.dependencies" class="smpl">WWW-Authenticate</a>        ; <a href="#Part7" id="rfc.xref.Part7.11"><cite title="HTTP/1.1, part 7: Authentication">[Part7]</cite></a>, <a href="p7-auth.html#header.www-authenticate" title="WWW-Authenticate">Section 3.4</a>
    900934</pre><p id="rfc.section.5.p.3">Response-header field names can be extended reliably only in combination with a change in the protocol version. However, new
    901          or experimental header fields <em class="bcp14">MAY</em> be given the semantics of response-header fields if all parties in the communication recognize them to be response-header
    902          fields. Unrecognized header fields are treated as entity-header fields.
    903       </p>
    904       <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a id="entity" href="#entity">Entity</a></h1>
    905       <p id="rfc.section.6.p.1">Request and Response messages <em class="bcp14">MAY</em> transfer an entity if not otherwise restricted by the request method or response status code. An entity consists of entity-header
    906          fields and an entity-body, although some responses will only include the entity-headers. HTTP entity-body and entity-header
    907          fields are defined in <a href="#Part3" id="rfc.xref.Part3.9"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>.
    908       </p>
    909       <p id="rfc.section.6.p.2">An entity-body is only present in a message when a message-body is present, as described in <a href="p1-messaging.html#message.body" title="Message Body">Section 3.3</a> of <a href="#Part1" id="rfc.xref.Part1.21"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>. The entity-body is obtained from the message-body by decoding any Transfer-Encoding that might have been applied to ensure
    910          safe and proper transfer of the message.
    911       </p>
    912       <h2 id="rfc.section.6.1"><a href="#rfc.section.6.1">6.1</a>&nbsp;<a id="identifying.response.associated.with.representation" href="#identifying.response.associated.with.representation">Identifying the Resource Associated with a Representation</a></h2>
    913       <p id="rfc.section.6.1.p.1">It is sometimes necessary to determine the identity of the resource associated with a representation.</p>
    914       <p id="rfc.section.6.1.p.2">An HTTP request representation, when present, is always associated with an anonymous (i.e., unidentified) resource.</p>
    915       <p id="rfc.section.6.1.p.3">In the common case, an HTTP response is a representation of the resource located at the Effective Request URI (see <a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 4.3</a> of <a href="#Part1" id="rfc.xref.Part1.22"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). However, this is not always the case. To determine the URI of the resource a response is associated with, the following
    916          rules are used (with the first applicable one being selected):
    917       </p>
    918       <ol>
    919          <li>If the response status code is 200 or 203 and the request method was GET, the response is a representation of the resource
    920             at the Effective Request URI.
    921          </li>
    922          <li>If the response status is 204, 206, or 304 and the request method was GET or HEAD, the response is a partial representation
    923             of the resource at the Effective Request URI (see <a href="p6-cache.html#combining.headers" title="Combining Responses">Section 2.8</a> of <a href="#Part6" id="rfc.xref.Part6.5"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a>).
    924          </li>
    925          <li>If the response has a Content-Location header, and that URI is the same as the Effective Request URI, the response is a representation
    926             of the resource at the Effective Request URI.
    927          </li>
    928          <li>If the response has a Content-Location header, and that URI is not the same as the Effective Request URI, the response asserts
    929             that it is a representation of the resource at the Content-Location URI (but it may not be).
    930          </li>
    931          <li>Otherwise, the response is a representation of an anonymous (i.e., unidentified) resource.</li>
    932       </ol>
    933       <p id="rfc.section.6.1.p.5"> <span class="comment" id="TODO-req-uri">[<a href="#TODO-req-uri" class="smpl">TODO-req-uri</a>: The comparison function is going to have to be defined somewhere, because we already need to compare URIs for things like
    934             cache invalidation.]</span>
    935       </p>
    936       <h1 id="rfc.section.7"><a href="#rfc.section.7">7.</a>&nbsp;<a id="method.definitions" href="#method.definitions">Method Definitions</a></h1>
    937       <p id="rfc.section.7.p.1">The set of common methods for HTTP/1.1 is defined below. Although this set can be expanded, additional methods cannot be assumed
    938          to share the same semantics for separately extended clients and servers.
    939       </p>
    940       <h2 id="rfc.section.7.1"><a href="#rfc.section.7.1">7.1</a>&nbsp;<a id="safe.and.idempotent" href="#safe.and.idempotent">Safe and Idempotent Methods</a></h2>
    941       <div id="rfc.iref.s.1"></div>
    942       <h3 id="rfc.section.7.1.1"><a href="#rfc.section.7.1.1">7.1.1</a>&nbsp;<a id="safe.methods" href="#safe.methods">Safe Methods</a></h3>
    943       <p id="rfc.section.7.1.1.p.1">Implementors should be aware that the software represents the user in their interactions over the Internet, and should be
    944          careful to allow the user to be aware of any actions they might take which may have an unexpected significance to themselves
    945          or others.
    946       </p>
    947       <p id="rfc.section.7.1.1.p.2">In particular, the convention has been established that the GET, HEAD, OPTIONS, and TRACE methods <em class="bcp14">SHOULD NOT</em> have the significance of taking an action other than retrieval. These methods ought to be considered "<dfn id="safe">safe</dfn>". This allows user agents to represent other methods, such as POST, PUT and DELETE, in a special way, so that the user is
    948          made aware of the fact that a possibly unsafe action is being requested.
    949       </p>
    950       <p id="rfc.section.7.1.1.p.3">Naturally, it is not possible to ensure that the server does not generate side-effects as a result of performing a GET request;
    951          in fact, some dynamic resources consider that a feature. The important distinction here is that the user did not request the
    952          side-effects, so therefore cannot be held accountable for them.
    953       </p>
    954       <div id="rfc.iref.i.1"></div>
    955       <h3 id="rfc.section.7.1.2"><a href="#rfc.section.7.1.2">7.1.2</a>&nbsp;<a id="idempotent.methods" href="#idempotent.methods">Idempotent Methods</a></h3>
    956       <p id="rfc.section.7.1.2.p.1">Methods can also have the property of "idempotence" in that, aside from error or expiration issues, the intended effect of
    957          multiple identical requests is the same as for a single request. The methods PUT, DELETE, and all safe methods are idempotent.
    958          It is important to note that idempotence refers only to changes requested by the client: a server is free to change its state
    959          due to multiple requests for the purpose of tracking those requests, versioning of results, etc.
    960       </p>
    961       <h2 id="rfc.section.7.2"><a href="#rfc.section.7.2">7.2</a>&nbsp;<a id="OPTIONS" href="#OPTIONS">OPTIONS</a></h2>
    962       <div id="rfc.iref.o.1"></div>
    963       <div id="rfc.iref.m.1"></div>
    964       <p id="rfc.section.7.2.p.1">The OPTIONS method represents a request for information about the communication options available on the request/response
    965          chain identified by the Effective Request URI. This method allows the client to determine the options and/or requirements
    966          associated with a resource, or the capabilities of a server, without implying a resource action or initiating a resource retrieval.
    967       </p>
    968       <p id="rfc.section.7.2.p.2">Responses to this method are not cacheable.</p>
    969       <p id="rfc.section.7.2.p.3">If the OPTIONS request includes an entity-body (as indicated by the presence of Content-Length or Transfer-Encoding), then
    970          the media type <em class="bcp14">MUST</em> be indicated by a Content-Type field. Although this specification does not define any use for such a body, future extensions
    971          to HTTP might use the OPTIONS body to make more detailed queries on the server.
    972       </p>
    973       <p id="rfc.section.7.2.p.4">If the request-target is an asterisk ("*"), the OPTIONS request is intended to apply to the server in general rather than
    974          to a specific resource. Since a server's communication options typically depend on the resource, the "*" request is only useful
    975          as a "ping" or "no-op" type of method; it does nothing beyond allowing the client to test the capabilities of the server.
    976          For example, this can be used to test a proxy for HTTP/1.1 compliance (or lack thereof).
    977       </p>
    978       <p id="rfc.section.7.2.p.5">If the request-target is not an asterisk, the OPTIONS request applies only to the options that are available when communicating
    979          with that resource.
    980       </p>
    981       <p id="rfc.section.7.2.p.6">A 200 response <em class="bcp14">SHOULD</em> include any header fields that indicate optional features implemented by the server and applicable to that resource (e.g.,
    982          Allow), possibly including extensions not defined by this specification. The response body, if any, <em class="bcp14">SHOULD</em> also include information about the communication options. The format for such a body is not defined by this specification,
    983          but might be defined by future extensions to HTTP. Content negotiation <em class="bcp14">MAY</em> be used to select the appropriate response format. If no response body is included, the response <em class="bcp14">MUST</em> include a Content-Length field with a field-value of "0".
    984       </p>
    985       <p id="rfc.section.7.2.p.7">The Max-Forwards request-header field <em class="bcp14">MAY</em> be used to target a specific proxy in the request chain. When a proxy receives an OPTIONS request on an absolute-URI for which
    986          request forwarding is permitted, the proxy <em class="bcp14">MUST</em> check for a Max-Forwards field. If the Max-Forwards field-value is zero ("0"), the proxy <em class="bcp14">MUST NOT</em> forward the message; instead, the proxy <em class="bcp14">SHOULD</em> respond with its own communication options. If the Max-Forwards field-value is an integer greater than zero, the proxy <em class="bcp14">MUST</em> decrement the field-value when it forwards the request. If no Max-Forwards field is present in the request, then the forwarded
    987          request <em class="bcp14">MUST NOT</em> include a Max-Forwards field.
    988       </p>
    989       <h2 id="rfc.section.7.3"><a href="#rfc.section.7.3">7.3</a>&nbsp;<a id="GET" href="#GET">GET</a></h2>
    990       <div id="rfc.iref.g.8"></div>
    991       <div id="rfc.iref.m.2"></div>
    992       <p id="rfc.section.7.3.p.1">The GET method means retrieve whatever information (in the form of an entity) currently corresponds to the resource identified
    993          by the Effective Request URI.
    994       </p>
    995       <p id="rfc.section.7.3.p.2">If the Effective Request URI identifies a data-producing process, it is the produced data which shall be returned as the entity
    996          in the response and not the source text of the process, unless that text happens to be the output of the process.
    997       </p>
    998       <p id="rfc.section.7.3.p.3">The semantics of the GET method change to a "conditional GET" if the request message includes an If-Modified-Since, If-Unmodified-Since,
    999          If-Match, If-None-Match, or If-Range header field. A conditional GET method requests that the entity be transferred only under
    1000          the circumstances described by the conditional header field(s). The conditional GET method is intended to reduce unnecessary
    1001          network usage by allowing cached entities to be refreshed without requiring multiple requests or transferring data already
    1002          held by the client.
    1003       </p>
    1004       <p id="rfc.section.7.3.p.4">The semantics of the GET method change to a "partial GET" if the request message includes a Range header field. A partial
    1005          GET requests that only part of the entity be transferred, as described in <a href="p5-range.html#header.range" title="Range">Section 5.4</a> of <a href="#Part5" id="rfc.xref.Part5.10"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>. The partial GET method is intended to reduce unnecessary network usage by allowing partially-retrieved entities to be completed
    1006          without transferring data already held by the client.
    1007       </p>
    1008       <p id="rfc.section.7.3.p.5">The response to a GET request is cacheable if and only if it meets the requirements for HTTP caching described in <a href="#Part6" id="rfc.xref.Part6.6"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a>.
    1009       </p>
    1010       <p id="rfc.section.7.3.p.6">See <a href="#encoding.sensitive.information.in.uris" title="Encoding Sensitive Information in URIs">Section&nbsp;11.2</a> for security considerations when used for forms.
    1011       </p>
    1012       <h2 id="rfc.section.7.4"><a href="#rfc.section.7.4">7.4</a>&nbsp;<a id="HEAD" href="#HEAD">HEAD</a></h2>
    1013       <div id="rfc.iref.h.1"></div>
    1014       <div id="rfc.iref.m.3"></div>
    1015       <p id="rfc.section.7.4.p.1">The HEAD method is identical to GET except that the server <em class="bcp14">MUST NOT</em> return a message-body in the response. The metainformation contained in the HTTP headers in response to a HEAD request <em class="bcp14">SHOULD</em> be identical to the information sent in response to a GET request. This method can be used for obtaining metainformation about
    1016          the entity implied by the request without transferring the entity-body itself. This method is often used for testing hypertext
    1017          links for validity, accessibility, and recent modification.
    1018       </p>
    1019       <p id="rfc.section.7.4.p.2">The response to a HEAD request <em class="bcp14">MAY</em> be cacheable in the sense that the information contained in the response <em class="bcp14">MAY</em> be used to update a previously cached entity from that resource. If the new field values indicate that the cached entity differs
    1020          from the current entity (as would be indicated by a change in Content-Length, Content-MD5, ETag or Last-Modified), then the
    1021          cache <em class="bcp14">MUST</em> treat the cache entry as stale.
    1022       </p>
    1023       <div id="rfc.iref.p.1"></div>
    1024       <div id="rfc.iref.m.4"></div>
    1025       <h2 id="rfc.section.7.5"><a href="#rfc.section.7.5">7.5</a>&nbsp;<a id="POST" href="#POST">POST</a></h2>
    1026       <p id="rfc.section.7.5.p.1">The POST method is used to request that the origin server accept the entity enclosed in the request as data to be processed
    1027          by the resource identified by the Effective Request URI. POST is designed to allow a uniform method to cover the following
    1028          functions:
    1029       </p>
    1030       <ul>
    1031          <li>Annotation of existing resources;</li>
    1032          <li>Posting a message to a bulletin board, newsgroup, mailing list, or similar group of articles;</li>
    1033          <li>Providing a block of data, such as the result of submitting a form, to a data-handling process;</li>
    1034          <li>Extending a database through an append operation.</li>
    1035       </ul>
    1036       <p id="rfc.section.7.5.p.2">The actual function performed by the POST method is determined by the server and is usually dependent on the Effective Request
    1037          URI.
    1038       </p>
    1039       <p id="rfc.section.7.5.p.3">The action performed by the POST method might not result in a resource that can be identified by a URI. In this case, either
    1040          200 (OK) or 204 (No Content) is the appropriate response status, depending on whether or not the response includes an entity
    1041          that describes the result.
    1042       </p>
    1043       <p id="rfc.section.7.5.p.4">If a resource has been created on the origin server, the response <em class="bcp14">SHOULD</em> be 201 (Created) and contain an entity which describes the status of the request and refers to the new resource, and a Location
    1044          header (see <a href="#header.location" id="rfc.xref.header.location.2" title="Location">Section&nbsp;9.4</a>).
    1045       </p>
    1046       <p id="rfc.section.7.5.p.5">Responses to this method are not cacheable, unless the response includes appropriate Cache-Control or Expires header fields.
    1047          However, the 303 (See Other) response can be used to direct the user agent to retrieve a cacheable resource.
    1048       </p>
    1049       <div id="rfc.iref.p.2"></div>
    1050       <div id="rfc.iref.m.5"></div>
    1051       <h2 id="rfc.section.7.6"><a href="#rfc.section.7.6">7.6</a>&nbsp;<a id="PUT" href="#PUT">PUT</a></h2>
    1052       <p id="rfc.section.7.6.p.1">The PUT method requests that the enclosed entity be stored at the Effective Request URI. If the Effective Request URI refers
    1053          to an already existing resource, the enclosed entity <em class="bcp14">SHOULD</em> be considered as a modified version of the one residing on the origin server. Otherwise, if the Effective Request URI does
    1054          not point to an existing resource, and that URI is capable of being defined as a new resource by the requesting user agent,
    1055          the origin server can create the resource with that URI.
    1056       </p>
    1057       <p id="rfc.section.7.6.p.2">If a new resource is created at the Effective Request URI, the origin server <em class="bcp14">MUST</em> inform the user agent via the 201 (Created) response. If an existing resource is modified, either the 200 (OK) or 204 (No
    1058          Content) response codes <em class="bcp14">SHOULD</em> be sent to indicate successful completion of the request.
    1059       </p>
    1060       <p id="rfc.section.7.6.p.3">If the resource could not be created or modified with the Effective Request URI, an appropriate error response <em class="bcp14">SHOULD</em> be given that reflects the nature of the problem. The recipient of the entity <em class="bcp14">MUST NOT</em> ignore any Content-* headers (headers starting with the prefix "Content-") that it does not understand or implement and <em class="bcp14">MUST</em> return a 501 (Not Implemented) response in such cases.
    1061       </p>
    1062       <p id="rfc.section.7.6.p.4">If the request passes through a cache and the Effective Request URI identifies one or more currently cached entities, those
    1063          entries <em class="bcp14">SHOULD</em> be treated as stale. Responses to this method are not cacheable.
    1064       </p>
    1065       <p id="rfc.section.7.6.p.5">The fundamental difference between the POST and PUT requests is reflected in the different meaning of the Effective Request
    1066          URI. The URI in a POST request identifies the resource that will handle the enclosed entity. That resource might be a data-accepting
    1067          process, a gateway to some other protocol, or a separate entity that accepts annotations. In contrast, the URI in a PUT request
    1068          identifies the entity enclosed with the request -- the user agent knows what URI is intended and the server <em class="bcp14">MUST NOT</em> attempt to apply the request to some other resource. If the server desires that the request be applied to a different URI,
    1069          it <em class="bcp14">MUST</em> send a 301 (Moved Permanently) response; the user agent <em class="bcp14">MAY</em> then make its own decision regarding whether or not to redirect the request.
    1070       </p>
    1071       <p id="rfc.section.7.6.p.6">A single resource <em class="bcp14">MAY</em> be identified by many different URIs. For example, an article might have a URI for identifying "the current version" which
    1072          is separate from the URI identifying each particular version. In this case, a PUT request on a general URI might result in
    1073          several other URIs being defined by the origin server.
    1074       </p>
    1075       <p id="rfc.section.7.6.p.7">HTTP/1.1 does not define how a PUT method affects the state of an origin server.</p>
    1076       <p id="rfc.section.7.6.p.8">Unless otherwise specified for a particular entity-header, the entity-headers in the PUT request <em class="bcp14">SHOULD</em> be applied to the resource created or modified by the PUT.
    1077       </p>
    1078       <div id="rfc.iref.d.1"></div>
    1079       <div id="rfc.iref.m.6"></div>
    1080       <h2 id="rfc.section.7.7"><a href="#rfc.section.7.7">7.7</a>&nbsp;<a id="DELETE" href="#DELETE">DELETE</a></h2>
    1081       <p id="rfc.section.7.7.p.1">The DELETE method requests that the origin server delete the resource identified by the Effective Request URI. This method <em class="bcp14">MAY</em> be overridden by human intervention (or other means) on the origin server. The client cannot be guaranteed that the operation
    1082          has been carried out, even if the status code returned from the origin server indicates that the action has been completed
    1083          successfully. However, the server <em class="bcp14">SHOULD NOT</em> indicate success unless, at the time the response is given, it intends to delete the resource or move it to an inaccessible
    1084          location.
    1085       </p>
    1086       <p id="rfc.section.7.7.p.2">A successful response <em class="bcp14">SHOULD</em> be 200 (OK) if the response includes an entity describing the status, 202 (Accepted) if the action has not yet been enacted,
    1087          or 204 (No Content) if the action has been enacted but the response does not include an entity.
    1088       </p>
    1089       <p id="rfc.section.7.7.p.3">If the request passes through a cache and the Effective Request URI identifies one or more currently cached entities, those
    1090          entries <em class="bcp14">SHOULD</em> be treated as stale. Responses to this method are not cacheable.
    1091       </p>
    1092       <h2 id="rfc.section.7.8"><a href="#rfc.section.7.8">7.8</a>&nbsp;<a id="TRACE" href="#TRACE">TRACE</a></h2>
    1093       <div id="rfc.iref.t.1"></div>
    1094       <div id="rfc.iref.m.7"></div>
    1095       <p id="rfc.section.7.8.p.1">The TRACE method is used to invoke a remote, application-layer loop-back of the request message. The final recipient of the
    1096          request <em class="bcp14">SHOULD</em> reflect the message received back to the client as the entity-body of a 200 (OK) response. The final recipient is either the
    1097          origin server or the first proxy or gateway to receive a Max-Forwards value of zero (0) in the request (see <a href="#header.max-forwards" id="rfc.xref.header.max-forwards.2" title="Max-Forwards">Section&nbsp;9.5</a>). A TRACE request <em class="bcp14">MUST NOT</em> include an entity.
    1098       </p>
    1099       <p id="rfc.section.7.8.p.2">TRACE allows the client to see what is being received at the other end of the request chain and use that data for testing
    1100          or diagnostic information. The value of the Via header field (<a href="p1-messaging.html#header.via" title="Via">Section 9.9</a> of <a href="#Part1" id="rfc.xref.Part1.23"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) is of particular interest, since it acts as a trace of the request chain. Use of the Max-Forwards header field allows the
    1101          client to limit the length of the request chain, which is useful for testing a chain of proxies forwarding messages in an
    1102          infinite loop.
    1103       </p>
    1104       <p id="rfc.section.7.8.p.3">If the request is valid, the response <em class="bcp14">SHOULD</em> contain the entire request message in the entity-body, with a Content-Type of "message/http" (see <a href="p1-messaging.html#internet.media.type.message.http" title="Internet Media Type message/http">Section 10.3.1</a> of <a href="#Part1" id="rfc.xref.Part1.24"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). Responses to this method <em class="bcp14">MUST NOT</em> be cached.
    1105       </p>
    1106       <div id="rfc.iref.c.1"></div>
    1107       <div id="rfc.iref.m.8"></div>
    1108       <h2 id="rfc.section.7.9"><a href="#rfc.section.7.9">7.9</a>&nbsp;<a id="CONNECT" href="#CONNECT">CONNECT</a></h2>
    1109       <p id="rfc.section.7.9.p.1">This specification reserves the method name CONNECT for use with a proxy that can dynamically switch to being a tunnel (e.g.,
    1110          SSL tunneling <a href="#RFC2817" id="rfc.xref.RFC2817.1"><cite title="Upgrading to TLS Within HTTP/1.1">[RFC2817]</cite></a>).
    1111       </p>
    1112       <h1 id="rfc.section.8"><a href="#rfc.section.8">8.</a>&nbsp;<a id="status.codes" href="#status.codes">Status Code Definitions</a></h1>
    1113       <p id="rfc.section.8.p.1">Each Status-Code is described below, including any metainformation required in the response.</p>
    1114       <h2 id="rfc.section.8.1"><a href="#rfc.section.8.1">8.1</a>&nbsp;<a id="status.1xx" href="#status.1xx">Informational 1xx</a></h2>
    1115       <p id="rfc.section.8.1.p.1">This class of status code indicates a provisional response, consisting only of the Status-Line and optional headers, and is
    1116          terminated by an empty line. There are no required headers for this class of status code. Since HTTP/1.0 did not define any
    1117          1xx status codes, servers <em class="bcp14">MUST NOT</em> send a 1xx response to an HTTP/1.0 client except under experimental conditions.
    1118       </p>
    1119       <p id="rfc.section.8.1.p.2">A client <em class="bcp14">MUST</em> be prepared to accept one or more 1xx status responses prior to a regular response, even if the client does not expect a 100
    1120          (Continue) status message. Unexpected 1xx status responses <em class="bcp14">MAY</em> be ignored by a user agent.
    1121       </p>
    1122       <p id="rfc.section.8.1.p.3">Proxies <em class="bcp14">MUST</em> forward 1xx responses, unless the connection between the proxy and its client has been closed, or unless the proxy itself
    1123          requested the generation of the 1xx response. (For example, if a proxy adds a "Expect: 100-continue" field when it forwards
    1124          a request, then it need not forward the corresponding 100 (Continue) response(s).)
    1125       </p>
    1126       <div id="rfc.iref.25"></div>
    1127       <div id="rfc.iref.s.2"></div>
    1128       <h3 id="rfc.section.8.1.1"><a href="#rfc.section.8.1.1">8.1.1</a>&nbsp;<a id="status.100" href="#status.100">100 Continue</a></h3>
    1129       <p id="rfc.section.8.1.1.p.1">The client <em class="bcp14">SHOULD</em> continue with its request. This interim response is used to inform the client that the initial part of the request has been
    1130          received and has not yet been rejected by the server. The client <em class="bcp14">SHOULD</em> continue by sending the remainder of the request or, if the request has already been completed, ignore this response. The
    1131          server <em class="bcp14">MUST</em> send a final response after the request has been completed. See <a href="p1-messaging.html#use.of.the.100.status" title="Use of the 100 (Continue) Status">Section 7.2.3</a> of <a href="#Part1" id="rfc.xref.Part1.25"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a> for detailed discussion of the use and handling of this status code.
    1132       </p>
    1133       <div id="rfc.iref.26"></div>
    1134       <div id="rfc.iref.s.3"></div>
    1135       <h3 id="rfc.section.8.1.2"><a href="#rfc.section.8.1.2">8.1.2</a>&nbsp;<a id="status.101" href="#status.101">101 Switching Protocols</a></h3>
    1136       <p id="rfc.section.8.1.2.p.1">The server understands and is willing to comply with the client's request, via the Upgrade message header field (<a href="p1-messaging.html#header.upgrade" title="Upgrade">Section 9.8</a> of <a href="#Part1" id="rfc.xref.Part1.26"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>), for a change in the application protocol being used on this connection. The server will switch protocols to those defined
    1137          by the response's Upgrade header field immediately after the empty line which terminates the 101 response.
    1138       </p>
    1139       <p id="rfc.section.8.1.2.p.2">The protocol <em class="bcp14">SHOULD</em> be switched only when it is advantageous to do so. For example, switching to a newer version of HTTP is advantageous over
    1140          older versions, and switching to a real-time, synchronous protocol might be advantageous when delivering resources that use
    1141          such features.
    1142       </p>
    1143       <h2 id="rfc.section.8.2"><a href="#rfc.section.8.2">8.2</a>&nbsp;<a id="status.2xx" href="#status.2xx">Successful 2xx</a></h2>
    1144       <p id="rfc.section.8.2.p.1">This class of status code indicates that the client's request was successfully received, understood, and accepted.</p>
    1145       <div id="rfc.iref.27"></div>
    1146       <div id="rfc.iref.s.4"></div>
    1147       <h3 id="rfc.section.8.2.1"><a href="#rfc.section.8.2.1">8.2.1</a>&nbsp;<a id="status.200" href="#status.200">200 OK</a></h3>
    1148       <p id="rfc.section.8.2.1.p.1">The request has succeeded. The information returned with the response is dependent on the method used in the request, for
    1149          example:
    1150       </p>
    1151       <dl>
    1152          <dt>GET</dt>
    1153          <dd>an entity corresponding to the requested resource is sent in the response;</dd>
    1154          <dt>HEAD</dt>
    1155          <dd>the entity-header fields corresponding to the requested resource are sent in the response without any message-body;</dd>
    1156          <dt>POST</dt>
    1157          <dd>an entity describing or containing the result of the action;</dd>
    1158          <dt>TRACE</dt>
    1159          <dd>an entity containing the request message as received by the end server.</dd>
    1160       </dl>
    1161       <div id="rfc.iref.28"></div>
    1162       <div id="rfc.iref.s.5"></div>
    1163       <h3 id="rfc.section.8.2.2"><a href="#rfc.section.8.2.2">8.2.2</a>&nbsp;<a id="status.201" href="#status.201">201 Created</a></h3>
    1164       <p id="rfc.section.8.2.2.p.1">The request has been fulfilled and has resulted in a new resource being created. The newly created resource can be referenced
    1165          by the URI(s) returned in the entity of the response, with the most specific URI for the resource given by a Location header
    1166          field. The response <em class="bcp14">SHOULD</em> include an entity containing a list of resource characteristics and location(s) from which the user or user agent can choose
    1167          the one most appropriate. The entity format is specified by the media type given in the Content-Type header field. The origin
    1168          server <em class="bcp14">MUST</em> create the resource before returning the 201 status code. If the action cannot be carried out immediately, the server <em class="bcp14">SHOULD</em> respond with 202 (Accepted) response instead.
    1169       </p>
    1170       <p id="rfc.section.8.2.2.p.2">A 201 response <em class="bcp14">MAY</em> contain an ETag response header field indicating the current value of the entity tag for the requested variant just created,
    1171          see <a href="p4-conditional.html#header.etag" title="ETag">Section 6.1</a> of <a href="#Part4" id="rfc.xref.Part4.14"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
    1172       </p>
    1173       <div id="rfc.iref.29"></div>
    1174       <div id="rfc.iref.s.6"></div>
    1175       <h3 id="rfc.section.8.2.3"><a href="#rfc.section.8.2.3">8.2.3</a>&nbsp;<a id="status.202" href="#status.202">202 Accepted</a></h3>
    1176       <p id="rfc.section.8.2.3.p.1">The request has been accepted for processing, but the processing has not been completed. The request might or might not eventually
    1177          be acted upon, as it might be disallowed when processing actually takes place. There is no facility for re-sending a status
    1178          code from an asynchronous operation such as this.
    1179       </p>
    1180       <p id="rfc.section.8.2.3.p.2">The 202 response is intentionally non-committal. Its purpose is to allow a server to accept a request for some other process
    1181          (perhaps a batch-oriented process that is only run once per day) without requiring that the user agent's connection to the
    1182          server persist until the process is completed. The entity returned with this response <em class="bcp14">SHOULD</em> include an indication of the request's current status and either a pointer to a status monitor or some estimate of when the
    1183          user can expect the request to be fulfilled.
    1184       </p>
    1185       <div id="rfc.iref.30"></div>
    1186       <div id="rfc.iref.s.7"></div>
    1187       <h3 id="rfc.section.8.2.4"><a href="#rfc.section.8.2.4">8.2.4</a>&nbsp;<a id="status.203" href="#status.203">203 Non-Authoritative Information</a></h3>
    1188       <p id="rfc.section.8.2.4.p.1">The returned metainformation in the entity-header is not the definitive set as available from the origin server, but is gathered
    1189          from a local or a third-party copy. The set presented <em class="bcp14">MAY</em> be a subset or superset of the original version. For example, including local annotation information about the resource might
    1190          result in a superset of the metainformation known by the origin server. Use of this response code is not required and is only
    1191          appropriate when the response would otherwise be 200 (OK).
    1192       </p>
    1193       <div id="rfc.iref.31"></div>
    1194       <div id="rfc.iref.s.8"></div>
    1195       <h3 id="rfc.section.8.2.5"><a href="#rfc.section.8.2.5">8.2.5</a>&nbsp;<a id="status.204" href="#status.204">204 No Content</a></h3>
    1196       <p id="rfc.section.8.2.5.p.1">The server has fulfilled the request but does not need to return an entity-body, and might want to return updated metainformation.
    1197          The response <em class="bcp14">MAY</em> include new or updated metainformation in the form of entity-headers, which if present <em class="bcp14">SHOULD</em> be associated with the requested variant.
    1198       </p>
    1199       <p id="rfc.section.8.2.5.p.2">If the client is a user agent, it <em class="bcp14">SHOULD NOT</em> change its document view from that which caused the request to be sent. This response is primarily intended to allow input
    1200          for actions to take place without causing a change to the user agent's active document view, although any new or updated metainformation <em class="bcp14">SHOULD</em> be applied to the document currently in the user agent's active view.
    1201       </p>
    1202       <p id="rfc.section.8.2.5.p.3">The 204 response <em class="bcp14">MUST NOT</em> include a message-body, and thus is always terminated by the first empty line after the header fields.
    1203       </p>
    1204       <div id="rfc.iref.32"></div>
    1205       <div id="rfc.iref.s.9"></div>
    1206       <h3 id="rfc.section.8.2.6"><a href="#rfc.section.8.2.6">8.2.6</a>&nbsp;<a id="status.205" href="#status.205">205 Reset Content</a></h3>
    1207       <p id="rfc.section.8.2.6.p.1">The server has fulfilled the request and the user agent <em class="bcp14">SHOULD</em> reset the document view which caused the request to be sent. This response is primarily intended to allow input for actions
    1208          to take place via user input, followed by a clearing of the form in which the input is given so that the user can easily initiate
    1209          another input action. The response <em class="bcp14">MUST NOT</em> include an entity.
    1210       </p>
    1211       <div id="rfc.iref.33"></div>
    1212       <div id="rfc.iref.s.10"></div>
    1213       <h3 id="rfc.section.8.2.7"><a href="#rfc.section.8.2.7">8.2.7</a>&nbsp;<a id="status.206" href="#status.206">206 Partial Content</a></h3>
    1214       <p id="rfc.section.8.2.7.p.1">The server has fulfilled the partial GET request for the resource and the enclosed entity is a partial representation as defined
    1215          in <a href="p5-range.html#status.206" title="206 Partial Content">Section 3.1</a> of <a href="#Part5" id="rfc.xref.Part5.11"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>.
    1216       </p>
    1217       <h2 id="rfc.section.8.3"><a href="#rfc.section.8.3">8.3</a>&nbsp;<a id="status.3xx" href="#status.3xx">Redirection 3xx</a></h2>
    1218       <p id="rfc.section.8.3.p.1">This class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request.
    1219          The action required <em class="bcp14">MAY</em> be carried out by the user agent without interaction with the user if and only if the method used in the second request is
    1220          known to be "safe", as defined in <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>. A client <em class="bcp14">SHOULD</em> detect infinite redirection loops, since such loops generate network traffic for each redirection.
    1221       </p>
    1222       <div class="note" id="rfc.section.8.3.p.2">
    1223          <p> <b>Note:</b> An earlier version of this specification recommended a maximum of five redirections (<a href="#RFC2068" id="rfc.xref.RFC2068.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a>, <a href="http://tools.ietf.org/html/rfc2068#section-10.3">Section 10.3</a>). Content developers should be aware that there might be clients that implement such a fixed limitation.
    1224          </p>
     935            or experimental header fields <em class="bcp14">MAY</em> be given the semantics of response-header fields if all parties in the communication recognize them to be response-header
     936            fields. Unrecognized header fields are treated as entity-header fields.
     937         </p>
    1225938      </div>
    1226       <div id="rfc.iref.34"></div>
    1227       <div id="rfc.iref.s.11"></div>
    1228       <h3 id="rfc.section.8.3.1"><a href="#rfc.section.8.3.1">8.3.1</a>&nbsp;<a id="status.300" href="#status.300">300 Multiple Choices</a></h3>
    1229       <p id="rfc.section.8.3.1.p.1">The requested resource corresponds to any one of a set of representations, each with its own specific location, and agent-driven
    1230          negotiation information (<a href="p3-payload.html#content.negotiation" title="Content Negotiation">Section 4</a> of <a href="#Part3" id="rfc.xref.Part3.10"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>) is being provided so that the user (or user agent) can select a preferred representation and redirect its request to that
    1231          location.
    1232       </p>
    1233       <p id="rfc.section.8.3.1.p.2">Unless it was a HEAD request, the response <em class="bcp14">SHOULD</em> include an entity containing a list of resource characteristics and location(s) from which the user or user agent can choose
    1234          the one most appropriate. The entity format is specified by the media type given in the Content-Type header field. Depending
    1235          upon the format and the capabilities of the user agent, selection of the most appropriate choice <em class="bcp14">MAY</em> be performed automatically. However, this specification does not define any standard for such automatic selection.
    1236       </p>
    1237       <p id="rfc.section.8.3.1.p.3">If the server has a preferred choice of representation, it <em class="bcp14">SHOULD</em> include the specific URI for that representation in the Location field; user agents <em class="bcp14">MAY</em> use the Location field value for automatic redirection. This response is cacheable unless indicated otherwise.
    1238       </p>
    1239       <div id="rfc.iref.35"></div>
    1240       <div id="rfc.iref.s.12"></div>
    1241       <h3 id="rfc.section.8.3.2"><a href="#rfc.section.8.3.2">8.3.2</a>&nbsp;<a id="status.301" href="#status.301">301 Moved Permanently</a></h3>
    1242       <p id="rfc.section.8.3.2.p.1">The requested resource has been assigned a new permanent URI and any future references to this resource <em class="bcp14">SHOULD</em> use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the Effective
    1243          Request URI to one or more of the new references returned by the server, where possible. This response is cacheable unless
    1244          indicated otherwise.
    1245       </p>
    1246       <p id="rfc.section.8.3.2.p.2">The new permanent URI <em class="bcp14">SHOULD</em> be given by the Location field in the response. Unless the request method was HEAD, the entity of the response <em class="bcp14">SHOULD</em> contain a short hypertext note with a hyperlink to the new URI(s).
    1247       </p>
    1248       <p id="rfc.section.8.3.2.p.3">If the 301 status code is received in response to a request method that is known to be "safe", as defined in <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>, then the request <em class="bcp14">MAY</em> be automatically redirected by the user agent without confirmation. Otherwise, the user agent <em class="bcp14">MUST NOT</em> automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which
    1249          the request was issued.
    1250       </p>
    1251       <div class="note" id="rfc.section.8.3.2.p.4">
    1252          <p> <b>Note:</b> When automatically redirecting a POST request after receiving a 301 status code, some existing HTTP/1.0 user agents will erroneously
    1253             change it into a GET request.
    1254          </p>
     939      <div id="entity">
     940         <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a href="#entity">Entity</a></h1>
     941         <p id="rfc.section.6.p.1">Request and Response messages <em class="bcp14">MAY</em> transfer an entity if not otherwise restricted by the request method or response status code. An entity consists of entity-header
     942            fields and an entity-body, although some responses will only include the entity-headers. HTTP entity-body and entity-header
     943            fields are defined in <a href="#Part3" id="rfc.xref.Part3.9"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>.
     944         </p>
     945         <p id="rfc.section.6.p.2">An entity-body is only present in a message when a message-body is present, as described in <a href="p1-messaging.html#message.body" title="Message Body">Section 3.3</a> of <a href="#Part1" id="rfc.xref.Part1.21"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>. The entity-body is obtained from the message-body by decoding any Transfer-Encoding that might have been applied to ensure
     946            safe and proper transfer of the message.
     947         </p>
     948         <div id="identifying.response.associated.with.representation">
     949            <h2 id="rfc.section.6.1"><a href="#rfc.section.6.1">6.1</a>&nbsp;<a href="#identifying.response.associated.with.representation">Identifying the Resource Associated with a Representation</a></h2>
     950            <p id="rfc.section.6.1.p.1">It is sometimes necessary to determine the identity of the resource associated with a representation.</p>
     951            <p id="rfc.section.6.1.p.2">An HTTP request representation, when present, is always associated with an anonymous (i.e., unidentified) resource.</p>
     952            <p id="rfc.section.6.1.p.3">In the common case, an HTTP response is a representation of the resource located at the Effective Request URI (see <a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 4.3</a> of <a href="#Part1" id="rfc.xref.Part1.22"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). However, this is not always the case. To determine the URI of the resource a response is associated with, the following
     953               rules are used (with the first applicable one being selected):
     954            </p>
     955            <ol>
     956               <li>If the response status code is 200 or 203 and the request method was GET, the response is a representation of the resource
     957                  at the Effective Request URI.
     958               </li>
     959               <li>If the response status is 204, 206, or 304 and the request method was GET or HEAD, the response is a partial representation
     960                  of the resource at the Effective Request URI (see <a href="p6-cache.html#combining.headers" title="Combining Responses">Section 2.8</a> of <a href="#Part6" id="rfc.xref.Part6.5"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a>).
     961               </li>
     962               <li>If the response has a Content-Location header, and that URI is the same as the Effective Request URI, the response is a representation
     963                  of the resource at the Effective Request URI.
     964               </li>
     965               <li>If the response has a Content-Location header, and that URI is not the same as the Effective Request URI, the response asserts
     966                  that it is a representation of the resource at the Content-Location URI (but it may not be).
     967               </li>
     968               <li>Otherwise, the response is a representation of an anonymous (i.e., unidentified) resource.</li>
     969            </ol>
     970            <p id="rfc.section.6.1.p.5"><span class="comment" id="TODO-req-uri">[<a href="#TODO-req-uri" class="smpl">TODO-req-uri</a>: The comparison function is going to have to be defined somewhere, because we already need to compare URIs for things like
     971                  cache invalidation.]</span>
     972            </p>
     973         </div>
    1255974      </div>
    1256       <div id="rfc.iref.36"></div>
    1257       <div id="rfc.iref.s.13"></div>
    1258       <h3 id="rfc.section.8.3.3"><a href="#rfc.section.8.3.3">8.3.3</a>&nbsp;<a id="status.302" href="#status.302">302 Found</a></h3>
    1259       <p id="rfc.section.8.3.3.p.1">The requested resource resides temporarily under a different URI. Since the redirection might be altered on occasion, the
    1260          client <em class="bcp14">SHOULD</em> continue to use the Effectice Request URI for future requests. This response is only cacheable if indicated by a Cache-Control
    1261          or Expires header field.
    1262       </p>
    1263       <p id="rfc.section.8.3.3.p.2">The temporary URI <em class="bcp14">SHOULD</em> be given by the Location field in the response. Unless the request method was HEAD, the entity of the response <em class="bcp14">SHOULD</em> contain a short hypertext note with a hyperlink to the new URI(s).
    1264       </p>
    1265       <p id="rfc.section.8.3.3.p.3">If the 302 status code is received in response to a request method that is known to be "safe", as defined in <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>, then the request <em class="bcp14">MAY</em> be automatically redirected by the user agent without confirmation. Otherwise, the user agent <em class="bcp14">MUST NOT</em> automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which
    1266          the request was issued.
    1267       </p>
    1268       <div class="note" id="rfc.section.8.3.3.p.4">
    1269          <p> <b>Note:</b> HTTP/1.0 (<a href="#RFC1945" id="rfc.xref.RFC1945.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.0">[RFC1945]</cite></a>, <a href="http://tools.ietf.org/html/rfc1945#section-9.3">Section 9.3</a>) and the first version of HTTP/1.1 (<a href="#RFC2068" id="rfc.xref.RFC2068.2"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a>, <a href="http://tools.ietf.org/html/rfc2068#section-10.3.3">Section 10.3.3</a>) specify that the client is not allowed to change the method on the redirected request. However, most existing user agent
    1270             implementations treat 302 as if it were a 303 response, performing a GET on the Location field-value regardless of the original
    1271             request method. Therefore, a previous version of this specification (<a href="#RFC2616" id="rfc.xref.RFC2616.2"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, <a href="http://tools.ietf.org/html/rfc2616#section-10.3.3">Section 10.3.3</a>) has added the status codes <a href="#status.303" id="rfc.xref.status.303.2">303</a> and <a href="#status.307" id="rfc.xref.status.307.2">307</a> for servers that wish to make unambiguously clear which kind of reaction is expected of the client.
    1272          </p>
     975      <div id="method.definitions">
     976         <h1 id="rfc.section.7"><a href="#rfc.section.7">7.</a>&nbsp;<a href="#method.definitions">Method Definitions</a></h1>
     977         <p id="rfc.section.7.p.1">The set of common methods for HTTP/1.1 is defined below. Although this set can be expanded, additional methods cannot be assumed
     978            to share the same semantics for separately extended clients and servers.
     979         </p>
     980         <div id="safe.and.idempotent">
     981            <h2 id="rfc.section.7.1"><a href="#rfc.section.7.1">7.1</a>&nbsp;<a href="#safe.and.idempotent">Safe and Idempotent Methods</a></h2>
     982            <div id="safe.methods">
     983               <div id="rfc.iref.s.1"></div>
     984               <h3 id="rfc.section.7.1.1"><a href="#rfc.section.7.1.1">7.1.1</a>&nbsp;<a href="#safe.methods">Safe Methods</a></h3>
     985               <p id="rfc.section.7.1.1.p.1">Implementors should be aware that the software represents the user in their interactions over the Internet, and should be
     986                  careful to allow the user to be aware of any actions they might take which may have an unexpected significance to themselves
     987                  or others.
     988               </p>
     989               <p id="rfc.section.7.1.1.p.2">In particular, the convention has been established that the GET, HEAD, OPTIONS, and TRACE methods <em class="bcp14">SHOULD NOT</em> have the significance of taking an action other than retrieval. These methods ought to be considered "<dfn id="safe">safe</dfn>". This allows user agents to represent other methods, such as POST, PUT and DELETE, in a special way, so that the user is
     990                  made aware of the fact that a possibly unsafe action is being requested.
     991               </p>
     992               <p id="rfc.section.7.1.1.p.3">Naturally, it is not possible to ensure that the server does not generate side-effects as a result of performing a GET request;
     993                  in fact, some dynamic resources consider that a feature. The important distinction here is that the user did not request the
     994                  side-effects, so therefore cannot be held accountable for them.
     995               </p>
     996            </div>
     997            <div id="idempotent.methods">
     998               <div id="rfc.iref.i.1"></div>
     999               <h3 id="rfc.section.7.1.2"><a href="#rfc.section.7.1.2">7.1.2</a>&nbsp;<a href="#idempotent.methods">Idempotent Methods</a></h3>
     1000               <p id="rfc.section.7.1.2.p.1">Methods can also have the property of "idempotence" in that, aside from error or expiration issues, the intended effect of
     1001                  multiple identical requests is the same as for a single request. The methods PUT, DELETE, and all safe methods are idempotent.
     1002                  It is important to note that idempotence refers only to changes requested by the client: a server is free to change its state
     1003                  due to multiple requests for the purpose of tracking those requests, versioning of results, etc.
     1004               </p>
     1005            </div>
     1006         </div>
     1007         <div id="OPTIONS">
     1008            <h2 id="rfc.section.7.2"><a href="#rfc.section.7.2">7.2</a>&nbsp;<a href="#OPTIONS">OPTIONS</a></h2>
     1009            <div id="rfc.iref.o.1"></div>
     1010            <div id="rfc.iref.m.1"></div>
     1011            <p id="rfc.section.7.2.p.1">The OPTIONS method represents a request for information about the communication options available on the request/response
     1012               chain identified by the Effective Request URI. This method allows the client to determine the options and/or requirements
     1013               associated with a resource, or the capabilities of a server, without implying a resource action or initiating a resource retrieval.
     1014            </p>
     1015            <p id="rfc.section.7.2.p.2">Responses to this method are not cacheable.</p>
     1016            <p id="rfc.section.7.2.p.3">If the OPTIONS request includes an entity-body (as indicated by the presence of Content-Length or Transfer-Encoding), then
     1017               the media type <em class="bcp14">MUST</em> be indicated by a Content-Type field. Although this specification does not define any use for such a body, future extensions
     1018               to HTTP might use the OPTIONS body to make more detailed queries on the server.
     1019            </p>
     1020            <p id="rfc.section.7.2.p.4">If the request-target is an asterisk ("*"), the OPTIONS request is intended to apply to the server in general rather than
     1021               to a specific resource. Since a server's communication options typically depend on the resource, the "*" request is only useful
     1022               as a "ping" or "no-op" type of method; it does nothing beyond allowing the client to test the capabilities of the server.
     1023               For example, this can be used to test a proxy for HTTP/1.1 compliance (or lack thereof).
     1024            </p>
     1025            <p id="rfc.section.7.2.p.5">If the request-target is not an asterisk, the OPTIONS request applies only to the options that are available when communicating
     1026               with that resource.
     1027            </p>
     1028            <p id="rfc.section.7.2.p.6">A 200 response <em class="bcp14">SHOULD</em> include any header fields that indicate optional features implemented by the server and applicable to that resource (e.g.,
     1029               Allow), possibly including extensions not defined by this specification. The response body, if any, <em class="bcp14">SHOULD</em> also include information about the communication options. The format for such a body is not defined by this specification,
     1030               but might be defined by future extensions to HTTP. Content negotiation <em class="bcp14">MAY</em> be used to select the appropriate response format. If no response body is included, the response <em class="bcp14">MUST</em> include a Content-Length field with a field-value of "0".
     1031            </p>
     1032            <p id="rfc.section.7.2.p.7">The Max-Forwards request-header field <em class="bcp14">MAY</em> be used to target a specific proxy in the request chain. When a proxy receives an OPTIONS request on an absolute-URI for which
     1033               request forwarding is permitted, the proxy <em class="bcp14">MUST</em> check for a Max-Forwards field. If the Max-Forwards field-value is zero ("0"), the proxy <em class="bcp14">MUST NOT</em> forward the message; instead, the proxy <em class="bcp14">SHOULD</em> respond with its own communication options. If the Max-Forwards field-value is an integer greater than zero, the proxy <em class="bcp14">MUST</em> decrement the field-value when it forwards the request. If no Max-Forwards field is present in the request, then the forwarded
     1034               request <em class="bcp14">MUST NOT</em> include a Max-Forwards field.
     1035            </p>
     1036         </div>
     1037         <div id="GET">
     1038            <h2 id="rfc.section.7.3"><a href="#rfc.section.7.3">7.3</a>&nbsp;<a href="#GET">GET</a></h2>
     1039            <div id="rfc.iref.g.8"></div>
     1040            <div id="rfc.iref.m.2"></div>
     1041            <p id="rfc.section.7.3.p.1">The GET method means retrieve whatever information (in the form of an entity) currently corresponds to the resource identified
     1042               by the Effective Request URI.
     1043            </p>
     1044            <p id="rfc.section.7.3.p.2">If the Effective Request URI identifies a data-producing process, it is the produced data which shall be returned as the entity
     1045               in the response and not the source text of the process, unless that text happens to be the output of the process.
     1046            </p>
     1047            <p id="rfc.section.7.3.p.3">The semantics of the GET method change to a "conditional GET" if the request message includes an If-Modified-Since, If-Unmodified-Since,
     1048               If-Match, If-None-Match, or If-Range header field. A conditional GET method requests that the entity be transferred only under
     1049               the circumstances described by the conditional header field(s). The conditional GET method is intended to reduce unnecessary
     1050               network usage by allowing cached entities to be refreshed without requiring multiple requests or transferring data already
     1051               held by the client.
     1052            </p>
     1053            <p id="rfc.section.7.3.p.4">The semantics of the GET method change to a "partial GET" if the request message includes a Range header field. A partial
     1054               GET requests that only part of the entity be transferred, as described in <a href="p5-range.html#header.range" title="Range">Section 5.4</a> of <a href="#Part5" id="rfc.xref.Part5.10"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>. The partial GET method is intended to reduce unnecessary network usage by allowing partially-retrieved entities to be completed
     1055               without transferring data already held by the client.
     1056            </p>
     1057            <p id="rfc.section.7.3.p.5">The response to a GET request is cacheable if and only if it meets the requirements for HTTP caching described in <a href="#Part6" id="rfc.xref.Part6.6"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a>.
     1058            </p>
     1059            <p id="rfc.section.7.3.p.6">See <a href="#encoding.sensitive.information.in.uris" title="Encoding Sensitive Information in URIs">Section&nbsp;11.2</a> for security considerations when used for forms.
     1060            </p>
     1061         </div>
     1062         <div id="HEAD">
     1063            <h2 id="rfc.section.7.4"><a href="#rfc.section.7.4">7.4</a>&nbsp;<a href="#HEAD">HEAD</a></h2>
     1064            <div id="rfc.iref.h.1"></div>
     1065            <div id="rfc.iref.m.3"></div>
     1066            <p id="rfc.section.7.4.p.1">The HEAD method is identical to GET except that the server <em class="bcp14">MUST NOT</em> return a message-body in the response. The metainformation contained in the HTTP headers in response to a HEAD request <em class="bcp14">SHOULD</em> be identical to the information sent in response to a GET request. This method can be used for obtaining metainformation about
     1067               the entity implied by the request without transferring the entity-body itself. This method is often used for testing hypertext
     1068               links for validity, accessibility, and recent modification.
     1069            </p>
     1070            <p id="rfc.section.7.4.p.2">The response to a HEAD request <em class="bcp14">MAY</em> be cacheable in the sense that the information contained in the response <em class="bcp14">MAY</em> be used to update a previously cached entity from that resource. If the new field values indicate that the cached entity differs
     1071               from the current entity (as would be indicated by a change in Content-Length, Content-MD5, ETag or Last-Modified), then the
     1072               cache <em class="bcp14">MUST</em> treat the cache entry as stale.
     1073            </p>
     1074         </div>
     1075         <div id="POST">
     1076            <div id="rfc.iref.p.1"></div>
     1077            <div id="rfc.iref.m.4"></div>
     1078            <h2 id="rfc.section.7.5"><a href="#rfc.section.7.5">7.5</a>&nbsp;<a href="#POST">POST</a></h2>
     1079            <p id="rfc.section.7.5.p.1">The POST method is used to request that the origin server accept the entity enclosed in the request as data to be processed
     1080               by the resource identified by the Effective Request URI. POST is designed to allow a uniform method to cover the following
     1081               functions:
     1082            </p>
     1083            <ul>
     1084               <li>Annotation of existing resources;</li>
     1085               <li>Posting a message to a bulletin board, newsgroup, mailing list, or similar group of articles;</li>
     1086               <li>Providing a block of data, such as the result of submitting a form, to a data-handling process;</li>
     1087               <li>Extending a database through an append operation.</li>
     1088            </ul>
     1089            <p id="rfc.section.7.5.p.2">The actual function performed by the POST method is determined by the server and is usually dependent on the Effective Request
     1090               URI.
     1091            </p>
     1092            <p id="rfc.section.7.5.p.3">The action performed by the POST method might not result in a resource that can be identified by a URI. In this case, either
     1093               200 (OK) or 204 (No Content) is the appropriate response status, depending on whether or not the response includes an entity
     1094               that describes the result.
     1095            </p>
     1096            <p id="rfc.section.7.5.p.4">If a resource has been created on the origin server, the response <em class="bcp14">SHOULD</em> be 201 (Created) and contain an entity which describes the status of the request and refers to the new resource, and a Location
     1097               header (see <a href="#header.location" id="rfc.xref.header.location.2" title="Location">Section&nbsp;9.4</a>).
     1098            </p>
     1099            <p id="rfc.section.7.5.p.5">Responses to this method are not cacheable, unless the response includes appropriate Cache-Control or Expires header fields.
     1100               However, the 303 (See Other) response can be used to direct the user agent to retrieve a cacheable resource.
     1101            </p>
     1102         </div>
     1103         <div id="PUT">
     1104            <div id="rfc.iref.p.2"></div>
     1105            <div id="rfc.iref.m.5"></div>
     1106            <h2 id="rfc.section.7.6"><a href="#rfc.section.7.6">7.6</a>&nbsp;<a href="#PUT">PUT</a></h2>
     1107            <p id="rfc.section.7.6.p.1">The PUT method requests that the enclosed entity be stored at the Effective Request URI. If the Effective Request URI refers
     1108               to an already existing resource, the enclosed entity <em class="bcp14">SHOULD</em> be considered as a modified version of the one residing on the origin server. Otherwise, if the Effective Request URI does
     1109               not point to an existing resource, and that URI is capable of being defined as a new resource by the requesting user agent,
     1110               the origin server can create the resource with that URI.
     1111            </p>
     1112            <p id="rfc.section.7.6.p.2">If a new resource is created at the Effective Request URI, the origin server <em class="bcp14">MUST</em> inform the user agent via the 201 (Created) response. If an existing resource is modified, either the 200 (OK) or 204 (No
     1113               Content) response codes <em class="bcp14">SHOULD</em> be sent to indicate successful completion of the request.
     1114            </p>
     1115            <p id="rfc.section.7.6.p.3">If the resource could not be created or modified with the Effective Request URI, an appropriate error response <em class="bcp14">SHOULD</em> be given that reflects the nature of the problem. The recipient of the entity <em class="bcp14">MUST NOT</em> ignore any Content-* headers (headers starting with the prefix "Content-") that it does not understand or implement and <em class="bcp14">MUST</em> return a 501 (Not Implemented) response in such cases.
     1116            </p>
     1117            <p id="rfc.section.7.6.p.4">If the request passes through a cache and the Effective Request URI identifies one or more currently cached entities, those
     1118               entries <em class="bcp14">SHOULD</em> be treated as stale. Responses to this method are not cacheable.
     1119            </p>
     1120            <p id="rfc.section.7.6.p.5">The fundamental difference between the POST and PUT requests is reflected in the different meaning of the Effective Request
     1121               URI. The URI in a POST request identifies the resource that will handle the enclosed entity. That resource might be a data-accepting
     1122               process, a gateway to some other protocol, or a separate entity that accepts annotations. In contrast, the URI in a PUT request
     1123               identifies the entity enclosed with the request -- the user agent knows what URI is intended and the server <em class="bcp14">MUST NOT</em> attempt to apply the request to some other resource. If the server desires that the request be applied to a different URI,
     1124               it <em class="bcp14">MUST</em> send a 301 (Moved Permanently) response; the user agent <em class="bcp14">MAY</em> then make its own decision regarding whether or not to redirect the request.
     1125            </p>
     1126            <p id="rfc.section.7.6.p.6">A single resource <em class="bcp14">MAY</em> be identified by many different URIs. For example, an article might have a URI for identifying "the current version" which
     1127               is separate from the URI identifying each particular version. In this case, a PUT request on a general URI might result in
     1128               several other URIs being defined by the origin server.
     1129            </p>
     1130            <p id="rfc.section.7.6.p.7">HTTP/1.1 does not define how a PUT method affects the state of an origin server.</p>
     1131            <p id="rfc.section.7.6.p.8">Unless otherwise specified for a particular entity-header, the entity-headers in the PUT request <em class="bcp14">SHOULD</em> be applied to the resource created or modified by the PUT.
     1132            </p>
     1133         </div>
     1134         <div id="DELETE">
     1135            <div id="rfc.iref.d.1"></div>
     1136            <div id="rfc.iref.m.6"></div>
     1137            <h2 id="rfc.section.7.7"><a href="#rfc.section.7.7">7.7</a>&nbsp;<a href="#DELETE">DELETE</a></h2>
     1138            <p id="rfc.section.7.7.p.1">The DELETE method requests that the origin server delete the resource identified by the Effective Request URI. This method <em class="bcp14">MAY</em> be overridden by human intervention (or other means) on the origin server. The client cannot be guaranteed that the operation
     1139               has been carried out, even if the status code returned from the origin server indicates that the action has been completed
     1140               successfully. However, the server <em class="bcp14">SHOULD NOT</em> indicate success unless, at the time the response is given, it intends to delete the resource or move it to an inaccessible
     1141               location.
     1142            </p>
     1143            <p id="rfc.section.7.7.p.2">A successful response <em class="bcp14">SHOULD</em> be 200 (OK) if the response includes an entity describing the status, 202 (Accepted) if the action has not yet been enacted,
     1144               or 204 (No Content) if the action has been enacted but the response does not include an entity.
     1145            </p>
     1146            <p id="rfc.section.7.7.p.3">If the request passes through a cache and the Effective Request URI identifies one or more currently cached entities, those
     1147               entries <em class="bcp14">SHOULD</em> be treated as stale. Responses to this method are not cacheable.
     1148            </p>
     1149         </div>
     1150         <div id="TRACE">
     1151            <h2 id="rfc.section.7.8"><a href="#rfc.section.7.8">7.8</a>&nbsp;<a href="#TRACE">TRACE</a></h2>
     1152            <div id="rfc.iref.t.1"></div>
     1153            <div id="rfc.iref.m.7"></div>
     1154            <p id="rfc.section.7.8.p.1">The TRACE method is used to invoke a remote, application-layer loop-back of the request message. The final recipient of the
     1155               request <em class="bcp14">SHOULD</em> reflect the message received back to the client as the entity-body of a 200 (OK) response. The final recipient is either the
     1156               origin server or the first proxy or gateway to receive a Max-Forwards value of zero (0) in the request (see <a href="#header.max-forwards" id="rfc.xref.header.max-forwards.2" title="Max-Forwards">Section&nbsp;9.5</a>). A TRACE request <em class="bcp14">MUST NOT</em> include an entity.
     1157            </p>
     1158            <p id="rfc.section.7.8.p.2">TRACE allows the client to see what is being received at the other end of the request chain and use that data for testing
     1159               or diagnostic information. The value of the Via header field (<a href="p1-messaging.html#header.via" title="Via">Section 9.9</a> of <a href="#Part1" id="rfc.xref.Part1.23"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) is of particular interest, since it acts as a trace of the request chain. Use of the Max-Forwards header field allows the
     1160               client to limit the length of the request chain, which is useful for testing a chain of proxies forwarding messages in an
     1161               infinite loop.
     1162            </p>
     1163            <p id="rfc.section.7.8.p.3">If the request is valid, the response <em class="bcp14">SHOULD</em> contain the entire request message in the entity-body, with a Content-Type of "message/http" (see <a href="p1-messaging.html#internet.media.type.message.http" title="Internet Media Type message/http">Section 10.3.1</a> of <a href="#Part1" id="rfc.xref.Part1.24"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). Responses to this method <em class="bcp14">MUST NOT</em> be cached.
     1164            </p>
     1165         </div>
     1166         <div id="CONNECT">
     1167            <div id="rfc.iref.c.1"></div>
     1168            <div id="rfc.iref.m.8"></div>
     1169            <h2 id="rfc.section.7.9"><a href="#rfc.section.7.9">7.9</a>&nbsp;<a href="#CONNECT">CONNECT</a></h2>
     1170            <p id="rfc.section.7.9.p.1">This specification reserves the method name CONNECT for use with a proxy that can dynamically switch to being a tunnel (e.g.,
     1171               SSL tunneling <a href="#RFC2817" id="rfc.xref.RFC2817.1"><cite title="Upgrading to TLS Within HTTP/1.1">[RFC2817]</cite></a>).
     1172            </p>
     1173         </div>
    12731174      </div>
    1274       <div id="rfc.iref.37"></div>
    1275       <div id="rfc.iref.s.14"></div>
    1276       <h3 id="rfc.section.8.3.4"><a href="#rfc.section.8.3.4">8.3.4</a>&nbsp;<a id="status.303" href="#status.303">303 See Other</a></h3>
    1277       <p id="rfc.section.8.3.4.p.1">The server directs the user agent to a different resource, indicated by a URI in the Location header field, that provides
    1278          an indirect response to the original request. The user agent <em class="bcp14">MAY</em> perform a GET request on the URI in the Location field in order to obtain a representation corresponding to the response,
    1279          be redirected again, or end with an error status. The Location URI is not a substitute reference for the originally requested
    1280          resource.
    1281       </p>
    1282       <p id="rfc.section.8.3.4.p.2">The 303 status is generally applicable to any HTTP method. It is primarily used to allow the output of a POST action to redirect
    1283          the user agent to a selected resource, since doing so provides the information corresponding to the POST response in a form
    1284          that can be separately identified, bookmarked, and cached independent of the original request.
    1285       </p>
    1286       <p id="rfc.section.8.3.4.p.3">A 303 response to a GET request indicates that the requested resource does not have a representation of its own that can be
    1287          transferred by the server over HTTP. The Location URI indicates a resource that is descriptive of the requested resource such
    1288          that the follow-on representation may be useful without implying that it adequately represents the previously requested resource.
    1289          Note that answers to the questions of what can be represented, what representations are adequate, and what might be a useful
    1290          description are outside the scope of HTTP and thus entirely determined by the URI owner(s).
    1291       </p>
    1292       <p id="rfc.section.8.3.4.p.4">A 303 response <em class="bcp14">SHOULD NOT</em> be cached unless it is indicated as cacheable by Cache-Control or Expires header fields. Except for responses to a HEAD request,
    1293          the entity of a 303 response <em class="bcp14">SHOULD</em> contain a short hypertext note with a hyperlink to the Location URI.
    1294       </p>
    1295       <div id="rfc.iref.38"></div>
    1296       <div id="rfc.iref.s.15"></div>
    1297       <h3 id="rfc.section.8.3.5"><a href="#rfc.section.8.3.5">8.3.5</a>&nbsp;<a id="status.304" href="#status.304">304 Not Modified</a></h3>
    1298       <p id="rfc.section.8.3.5.p.1">The response to the request has not been modified since the conditions indicated by the client's conditional GET request,
    1299          as defined in <a href="p4-conditional.html#status.304" title="304 Not Modified">Section 3.1</a> of <a href="#Part4" id="rfc.xref.Part4.15"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
    1300       </p>
    1301       <div id="rfc.iref.39"></div>
    1302       <div id="rfc.iref.s.16"></div>
    1303       <h3 id="rfc.section.8.3.6"><a href="#rfc.section.8.3.6">8.3.6</a>&nbsp;<a id="status.305" href="#status.305">305 Use Proxy</a></h3>
    1304       <p id="rfc.section.8.3.6.p.1">The 305 status was defined in a previous version of this specification (see <a href="#changes.from.rfc.2616" title="Changes from RFC 2616">Appendix&nbsp;A.2</a>), and is now deprecated.
    1305       </p>
    1306       <div id="rfc.iref.40"></div>
    1307       <div id="rfc.iref.s.17"></div>
    1308       <h3 id="rfc.section.8.3.7"><a href="#rfc.section.8.3.7">8.3.7</a>&nbsp;<a id="status.306" href="#status.306">306 (Unused)</a></h3>
    1309       <p id="rfc.section.8.3.7.p.1">The 306 status code was used in a previous version of the specification, is no longer used, and the code is reserved.</p>
    1310       <div id="rfc.iref.41"></div>
    1311       <div id="rfc.iref.s.18"></div>
    1312       <h3 id="rfc.section.8.3.8"><a href="#rfc.section.8.3.8">8.3.8</a>&nbsp;<a id="status.307" href="#status.307">307 Temporary Redirect</a></h3>
    1313       <p id="rfc.section.8.3.8.p.1">The requested resource resides temporarily under a different URI. Since the redirection <em class="bcp14">MAY</em> be altered on occasion, the client <em class="bcp14">SHOULD</em> continue to use the Effective Request URI for future requests. This response is only cacheable if indicated by a Cache-Control
    1314          or Expires header field.
    1315       </p>
    1316       <p id="rfc.section.8.3.8.p.2">The temporary URI <em class="bcp14">SHOULD</em> be given by the Location field in the response. Unless the request method was HEAD, the entity of the response <em class="bcp14">SHOULD</em> contain a short hypertext note with a hyperlink to the new URI(s) , since many pre-HTTP/1.1 user agents do not understand
    1317          the 307 status. Therefore, the note <em class="bcp14">SHOULD</em> contain the information necessary for a user to repeat the original request on the new URI.
    1318       </p>
    1319       <p id="rfc.section.8.3.8.p.3">If the 307 status code is received in response to a request method that is known to be "safe", as defined in <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>, then the request <em class="bcp14">MAY</em> be automatically redirected by the user agent without confirmation. Otherwise, the user agent <em class="bcp14">MUST NOT</em> automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which
    1320          the request was issued.
    1321       </p>
    1322       <h2 id="rfc.section.8.4"><a href="#rfc.section.8.4">8.4</a>&nbsp;<a id="status.4xx" href="#status.4xx">Client Error 4xx</a></h2>
    1323       <p id="rfc.section.8.4.p.1">The 4xx class of status code is intended for cases in which the client seems to have erred. Except when responding to a HEAD
    1324          request, the server <em class="bcp14">SHOULD</em> include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition.
    1325          These status codes are applicable to any request method. User agents <em class="bcp14">SHOULD</em> display any included entity to the user.
    1326       </p>
    1327       <p id="rfc.section.8.4.p.2">If the client is sending data, a server implementation using TCP <em class="bcp14">SHOULD</em> be careful to ensure that the client acknowledges receipt of the packet(s) containing the response, before the server closes
    1328          the input connection. If the client continues sending data to the server after the close, the server's TCP stack will send
    1329          a reset packet to the client, which may erase the client's unacknowledged input buffers before they can be read and interpreted
    1330          by the HTTP application.
    1331       </p>
    1332       <div id="rfc.iref.42"></div>
    1333       <div id="rfc.iref.s.19"></div>
    1334       <h3 id="rfc.section.8.4.1"><a href="#rfc.section.8.4.1">8.4.1</a>&nbsp;<a id="status.400" href="#status.400">400 Bad Request</a></h3>
    1335       <p id="rfc.section.8.4.1.p.1">The request could not be understood by the server due to malformed syntax. The client <em class="bcp14">SHOULD NOT</em> repeat the request without modifications.
    1336       </p>
    1337       <div id="rfc.iref.43"></div>
    1338       <div id="rfc.iref.s.20"></div>
    1339       <h3 id="rfc.section.8.4.2"><a href="#rfc.section.8.4.2">8.4.2</a>&nbsp;<a id="status.401" href="#status.401">401 Unauthorized</a></h3>
    1340       <p id="rfc.section.8.4.2.p.1">The request requires user authentication (see <a href="p7-auth.html#status.401" title="401 Unauthorized">Section 2.1</a> of <a href="#Part7" id="rfc.xref.Part7.12"><cite title="HTTP/1.1, part 7: Authentication">[Part7]</cite></a>).
    1341       </p>
    1342       <div id="rfc.iref.44"></div>
    1343       <div id="rfc.iref.s.21"></div>
    1344       <h3 id="rfc.section.8.4.3"><a href="#rfc.section.8.4.3">8.4.3</a>&nbsp;<a id="status.402" href="#status.402">402 Payment Required</a></h3>
    1345       <p id="rfc.section.8.4.3.p.1">This code is reserved for future use.</p>
    1346       <div id="rfc.iref.45"></div>
    1347       <div id="rfc.iref.s.22"></div>
    1348       <h3 id="rfc.section.8.4.4"><a href="#rfc.section.8.4.4">8.4.4</a>&nbsp;<a id="status.403" href="#status.403">403 Forbidden</a></h3>
    1349       <p id="rfc.section.8.4.4.p.1">The server understood the request, but is refusing to fulfill it. Authorization will not help and the request <em class="bcp14">SHOULD NOT</em> be repeated. If the request method was not HEAD and the server wishes to make public why the request has not been fulfilled,
    1350          it <em class="bcp14">SHOULD</em> describe the reason for the refusal in the entity. If the server does not wish to make this information available to the client,
    1351          the status code 404 (Not Found) can be used instead.
    1352       </p>
    1353       <div id="rfc.iref.46"></div>
    1354       <div id="rfc.iref.s.23"></div>
    1355       <h3 id="rfc.section.8.4.5"><a href="#rfc.section.8.4.5">8.4.5</a>&nbsp;<a id="status.404" href="#status.404">404 Not Found</a></h3>
    1356       <p id="rfc.section.8.4.5.p.1">The server has not found anything matching the Effective Request URI. No indication is given of whether the condition is temporary
    1357          or permanent. The 410 (Gone) status code <em class="bcp14">SHOULD</em> be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable
    1358          and has no forwarding address. This status code is commonly used when the server does not wish to reveal exactly why the request
    1359          has been refused, or when no other response is applicable.
    1360       </p>
    1361       <div id="rfc.iref.47"></div>
    1362       <div id="rfc.iref.s.24"></div>
    1363       <h3 id="rfc.section.8.4.6"><a href="#rfc.section.8.4.6">8.4.6</a>&nbsp;<a id="status.405" href="#status.405">405 Method Not Allowed</a></h3>
    1364       <p id="rfc.section.8.4.6.p.1">The method specified in the Request-Line is not allowed for the resource identified by the Effective Request URI. The response <em class="bcp14">MUST</em> include an Allow header containing a list of valid methods for the requested resource.
    1365       </p>
    1366       <div id="rfc.iref.48"></div>
    1367       <div id="rfc.iref.s.25"></div>
    1368       <h3 id="rfc.section.8.4.7"><a href="#rfc.section.8.4.7">8.4.7</a>&nbsp;<a id="status.406" href="#status.406">406 Not Acceptable</a></h3>
    1369       <p id="rfc.section.8.4.7.p.1">The resource identified by the request is only capable of generating response entities which have content characteristics
    1370          not acceptable according to the accept headers sent in the request.
    1371       </p>
    1372       <p id="rfc.section.8.4.7.p.2">Unless it was a HEAD request, the response <em class="bcp14">SHOULD</em> include an entity containing a list of available entity characteristics and location(s) from which the user or user agent
    1373          can choose the one most appropriate. The entity format is specified by the media type given in the Content-Type header field.
    1374          Depending upon the format and the capabilities of the user agent, selection of the most appropriate choice <em class="bcp14">MAY</em> be performed automatically. However, this specification does not define any standard for such automatic selection.
    1375       </p>
    1376       <div class="note" id="rfc.section.8.4.7.p.3">
    1377          <p> <b>Note:</b> HTTP/1.1 servers are allowed to return responses which are not acceptable according to the accept headers sent in the request.
    1378             In some cases, this may even be preferable to sending a 406 response. User agents are encouraged to inspect the headers of
    1379             an incoming response to determine if it is acceptable.
    1380          </p>
     1175      <div id="status.codes">
     1176         <h1 id="rfc.section.8"><a href="#rfc.section.8">8.</a>&nbsp;<a href="#status.codes">Status Code Definitions</a></h1>
     1177         <p id="rfc.section.8.p.1">Each Status-Code is described below, including any metainformation required in the response.</p>
     1178         <div id="status.1xx">
     1179            <h2 id="rfc.section.8.1"><a href="#rfc.section.8.1">8.1</a>&nbsp;<a href="#status.1xx">Informational 1xx</a></h2>
     1180            <p id="rfc.section.8.1.p.1">This class of status code indicates a provisional response, consisting only of the Status-Line and optional headers, and is
     1181               terminated by an empty line. There are no required headers for this class of status code. Since HTTP/1.0 did not define any
     1182               1xx status codes, servers <em class="bcp14">MUST NOT</em> send a 1xx response to an HTTP/1.0 client except under experimental conditions.
     1183            </p>
     1184            <p id="rfc.section.8.1.p.2">A client <em class="bcp14">MUST</em> be prepared to accept one or more 1xx status responses prior to a regular response, even if the client does not expect a 100
     1185               (Continue) status message. Unexpected 1xx status responses <em class="bcp14">MAY</em> be ignored by a user agent.
     1186            </p>
     1187            <p id="rfc.section.8.1.p.3">Proxies <em class="bcp14">MUST</em> forward 1xx responses, unless the connection between the proxy and its client has been closed, or unless the proxy itself
     1188               requested the generation of the 1xx response. (For example, if a proxy adds a "Expect: 100-continue" field when it forwards
     1189               a request, then it need not forward the corresponding 100 (Continue) response(s).)
     1190            </p>
     1191            <div id="status.100">
     1192               <div id="rfc.iref.1.1"></div>
     1193               <div id="rfc.iref.s.2"></div>
     1194               <h3 id="rfc.section.8.1.1"><a href="#rfc.section.8.1.1">8.1.1</a>&nbsp;<a href="#status.100">100 Continue</a></h3>
     1195               <p id="rfc.section.8.1.1.p.1">The client <em class="bcp14">SHOULD</em> continue with its request. This interim response is used to inform the client that the initial part of the request has been
     1196                  received and has not yet been rejected by the server. The client <em class="bcp14">SHOULD</em> continue by sending the remainder of the request or, if the request has already been completed, ignore this response. The
     1197                  server <em class="bcp14">MUST</em> send a final response after the request has been completed. See <a href="p1-messaging.html#use.of.the.100.status" title="Use of the 100 (Continue) Status">Section 7.2.3</a> of <a href="#Part1" id="rfc.xref.Part1.25"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a> for detailed discussion of the use and handling of this status code.
     1198               </p>
     1199            </div>
     1200            <div id="status.101">
     1201               <div id="rfc.iref.1.2"></div>
     1202               <div id="rfc.iref.s.3"></div>
     1203               <h3 id="rfc.section.8.1.2"><a href="#rfc.section.8.1.2">8.1.2</a>&nbsp;<a href="#status.101">101 Switching Protocols</a></h3>
     1204               <p id="rfc.section.8.1.2.p.1">The server understands and is willing to comply with the client's request, via the Upgrade message header field (<a href="p1-messaging.html#header.upgrade" title="Upgrade">Section 9.8</a> of <a href="#Part1" id="rfc.xref.Part1.26"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>), for a change in the application protocol being used on this connection. The server will switch protocols to those defined
     1205                  by the response's Upgrade header field immediately after the empty line which terminates the 101 response.
     1206               </p>
     1207               <p id="rfc.section.8.1.2.p.2">The protocol <em class="bcp14">SHOULD</em> be switched only when it is advantageous to do so. For example, switching to a newer version of HTTP is advantageous over
     1208                  older versions, and switching to a real-time, synchronous protocol might be advantageous when delivering resources that use
     1209                  such features.
     1210               </p>
     1211            </div>
     1212         </div>
     1213         <div id="status.2xx">
     1214            <h2 id="rfc.section.8.2"><a href="#rfc.section.8.2">8.2</a>&nbsp;<a href="#status.2xx">Successful 2xx</a></h2>
     1215            <p id="rfc.section.8.2.p.1">This class of status code indicates that the client's request was successfully received, understood, and accepted.</p>
     1216            <div id="status.200">
     1217               <div id="rfc.iref.2.1"></div>
     1218               <div id="rfc.iref.s.4"></div>
     1219               <h3 id="rfc.section.8.2.1"><a href="#rfc.section.8.2.1">8.2.1</a>&nbsp;<a href="#status.200">200 OK</a></h3>
     1220               <p id="rfc.section.8.2.1.p.1">The request has succeeded. The information returned with the response is dependent on the method used in the request, for
     1221                  example:
     1222               </p>
     1223               <dl>
     1224                  <dt>GET</dt>
     1225                  <dd>an entity corresponding to the requested resource is sent in the response;</dd>
     1226                  <dt>HEAD</dt>
     1227                  <dd>the entity-header fields corresponding to the requested resource are sent in the response without any message-body;</dd>
     1228                  <dt>POST</dt>
     1229                  <dd>an entity describing or containing the result of the action;</dd>
     1230                  <dt>TRACE</dt>
     1231                  <dd>an entity containing the request message as received by the end server.</dd>
     1232               </dl>
     1233            </div>
     1234            <div id="status.201">
     1235               <div id="rfc.iref.2.2"></div>
     1236               <div id="rfc.iref.s.5"></div>
     1237               <h3 id="rfc.section.8.2.2"><a href="#rfc.section.8.2.2">8.2.2</a>&nbsp;<a href="#status.201">201 Created</a></h3>
     1238               <p id="rfc.section.8.2.2.p.1">The request has been fulfilled and has resulted in a new resource being created. The newly created resource can be referenced
     1239                  by the URI(s) returned in the entity of the response, with the most specific URI for the resource given by a Location header
     1240                  field. The response <em class="bcp14">SHOULD</em> include an entity containing a list of resource characteristics and location(s) from which the user or user agent can choose
     1241                  the one most appropriate. The entity format is specified by the media type given in the Content-Type header field. The origin
     1242                  server <em class="bcp14">MUST</em> create the resource before returning the 201 status code. If the action cannot be carried out immediately, the server <em class="bcp14">SHOULD</em> respond with 202 (Accepted) response instead.
     1243               </p>
     1244               <p id="rfc.section.8.2.2.p.2">A 201 response <em class="bcp14">MAY</em> contain an ETag response header field indicating the current value of the entity tag for the requested variant just created,
     1245                  see <a href="p4-conditional.html#header.etag" title="ETag">Section 6.1</a> of <a href="#Part4" id="rfc.xref.Part4.14"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
     1246               </p>
     1247            </div>
     1248            <div id="status.202">
     1249               <div id="rfc.iref.2.3"></div>
     1250               <div id="rfc.iref.s.6"></div>
     1251               <h3 id="rfc.section.8.2.3"><a href="#rfc.section.8.2.3">8.2.3</a>&nbsp;<a href="#status.202">202 Accepted</a></h3>
     1252               <p id="rfc.section.8.2.3.p.1">The request has been accepted for processing, but the processing has not been completed. The request might or might not eventually
     1253                  be acted upon, as it might be disallowed when processing actually takes place. There is no facility for re-sending a status
     1254                  code from an asynchronous operation such as this.
     1255               </p>
     1256               <p id="rfc.section.8.2.3.p.2">The 202 response is intentionally non-committal. Its purpose is to allow a server to accept a request for some other process
     1257                  (perhaps a batch-oriented process that is only run once per day) without requiring that the user agent's connection to the
     1258                  server persist until the process is completed. The entity returned with this response <em class="bcp14">SHOULD</em> include an indication of the request's current status and either a pointer to a status monitor or some estimate of when the
     1259                  user can expect the request to be fulfilled.
     1260               </p>
     1261            </div>
     1262            <div id="status.203">
     1263               <div id="rfc.iref.2.4"></div>
     1264               <div id="rfc.iref.s.7"></div>
     1265               <h3 id="rfc.section.8.2.4"><a href="#rfc.section.8.2.4">8.2.4</a>&nbsp;<a href="#status.203">203 Non-Authoritative Information</a></h3>
     1266               <p id="rfc.section.8.2.4.p.1">The returned metainformation in the entity-header is not the definitive set as available from the origin server, but is gathered
     1267                  from a local or a third-party copy. The set presented <em class="bcp14">MAY</em> be a subset or superset of the original version. For example, including local annotation information about the resource might
     1268                  result in a superset of the metainformation known by the origin server. Use of this response code is not required and is only
     1269                  appropriate when the response would otherwise be 200 (OK).
     1270               </p>
     1271            </div>
     1272            <div id="status.204">
     1273               <div id="rfc.iref.2.5"></div>
     1274               <div id="rfc.iref.s.8"></div>
     1275               <h3 id="rfc.section.8.2.5"><a href="#rfc.section.8.2.5">8.2.5</a>&nbsp;<a href="#status.204">204 No Content</a></h3>
     1276               <p id="rfc.section.8.2.5.p.1">The server has fulfilled the request but does not need to return an entity-body, and might want to return updated metainformation.
     1277                  The response <em class="bcp14">MAY</em> include new or updated metainformation in the form of entity-headers, which if present <em class="bcp14">SHOULD</em> be associated with the requested variant.
     1278               </p>
     1279               <p id="rfc.section.8.2.5.p.2">If the client is a user agent, it <em class="bcp14">SHOULD NOT</em> change its document view from that which caused the request to be sent. This response is primarily intended to allow input
     1280                  for actions to take place without causing a change to the user agent's active document view, although any new or updated metainformation <em class="bcp14">SHOULD</em> be applied to the document currently in the user agent's active view.
     1281               </p>
     1282               <p id="rfc.section.8.2.5.p.3">The 204 response <em class="bcp14">MUST NOT</em> include a message-body, and thus is always terminated by the first empty line after the header fields.
     1283               </p>
     1284            </div>
     1285            <div id="status.205">
     1286               <div id="rfc.iref.2.6"></div>
     1287               <div id="rfc.iref.s.9"></div>
     1288               <h3 id="rfc.section.8.2.6"><a href="#rfc.section.8.2.6">8.2.6</a>&nbsp;<a href="#status.205">205 Reset Content</a></h3>
     1289               <p id="rfc.section.8.2.6.p.1">The server has fulfilled the request and the user agent <em class="bcp14">SHOULD</em> reset the document view which caused the request to be sent. This response is primarily intended to allow input for actions
     1290                  to take place via user input, followed by a clearing of the form in which the input is given so that the user can easily initiate
     1291                  another input action. The response <em class="bcp14">MUST NOT</em> include an entity.
     1292               </p>
     1293            </div>
     1294            <div id="status.206">
     1295               <div id="rfc.iref.2.7"></div>
     1296               <div id="rfc.iref.s.10"></div>
     1297               <h3 id="rfc.section.8.2.7"><a href="#rfc.section.8.2.7">8.2.7</a>&nbsp;<a href="#status.206">206 Partial Content</a></h3>
     1298               <p id="rfc.section.8.2.7.p.1">The server has fulfilled the partial GET request for the resource and the enclosed entity is a partial representation as defined
     1299                  in <a href="p5-range.html#status.206" title="206 Partial Content">Section 3.1</a> of <a href="#Part5" id="rfc.xref.Part5.11"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>.
     1300               </p>
     1301            </div>
     1302         </div>
     1303         <div id="status.3xx">
     1304            <h2 id="rfc.section.8.3"><a href="#rfc.section.8.3">8.3</a>&nbsp;<a href="#status.3xx">Redirection 3xx</a></h2>
     1305            <p id="rfc.section.8.3.p.1">This class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request.
     1306               The action required <em class="bcp14">MAY</em> be carried out by the user agent without interaction with the user if and only if the method used in the second request is
     1307               known to be "safe", as defined in <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>. A client <em class="bcp14">SHOULD</em> detect infinite redirection loops, since such loops generate network traffic for each redirection.
     1308            </p>
     1309            <div class="note" id="rfc.section.8.3.p.2">
     1310               <p><b>Note:</b> An earlier version of this specification recommended a maximum of five redirections (<a href="#RFC2068" id="rfc.xref.RFC2068.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a>, <a href="https://tools.ietf.org/html/rfc2068#section-10.3">Section 10.3</a>). Content developers should be aware that there might be clients that implement such a fixed limitation.
     1311               </p>
     1312            </div>
     1313            <div id="status.300">
     1314               <div id="rfc.iref.3.1"></div>
     1315               <div id="rfc.iref.s.11"></div>
     1316               <h3 id="rfc.section.8.3.1"><a href="#rfc.section.8.3.1">8.3.1</a>&nbsp;<a href="#status.300">300 Multiple Choices</a></h3>
     1317               <p id="rfc.section.8.3.1.p.1">The requested resource corresponds to any one of a set of representations, each with its own specific location, and agent-driven
     1318                  negotiation information (<a href="p3-payload.html#content.negotiation" title="Content Negotiation">Section 4</a> of <a href="#Part3" id="rfc.xref.Part3.10"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>) is being provided so that the user (or user agent) can select a preferred representation and redirect its request to that
     1319                  location.
     1320               </p>
     1321               <p id="rfc.section.8.3.1.p.2">Unless it was a HEAD request, the response <em class="bcp14">SHOULD</em> include an entity containing a list of resource characteristics and location(s) from which the user or user agent can choose
     1322                  the one most appropriate. The entity format is specified by the media type given in the Content-Type header field. Depending
     1323                  upon the format and the capabilities of the user agent, selection of the most appropriate choice <em class="bcp14">MAY</em> be performed automatically. However, this specification does not define any standard for such automatic selection.
     1324               </p>
     1325               <p id="rfc.section.8.3.1.p.3">If the server has a preferred choice of representation, it <em class="bcp14">SHOULD</em> include the specific URI for that representation in the Location field; user agents <em class="bcp14">MAY</em> use the Location field value for automatic redirection. This response is cacheable unless indicated otherwise.
     1326               </p>
     1327            </div>
     1328            <div id="status.301">
     1329               <div id="rfc.iref.3.2"></div>
     1330               <div id="rfc.iref.s.12"></div>
     1331               <h3 id="rfc.section.8.3.2"><a href="#rfc.section.8.3.2">8.3.2</a>&nbsp;<a href="#status.301">301 Moved Permanently</a></h3>
     1332               <p id="rfc.section.8.3.2.p.1">The requested resource has been assigned a new permanent URI and any future references to this resource <em class="bcp14">SHOULD</em> use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the Effective
     1333                  Request URI to one or more of the new references returned by the server, where possible. This response is cacheable unless
     1334                  indicated otherwise.
     1335               </p>
     1336               <p id="rfc.section.8.3.2.p.2">The new permanent URI <em class="bcp14">SHOULD</em> be given by the Location field in the response. Unless the request method was HEAD, the entity of the response <em class="bcp14">SHOULD</em> contain a short hypertext note with a hyperlink to the new URI(s).
     1337               </p>
     1338               <p id="rfc.section.8.3.2.p.3">If the 301 status code is received in response to a request method that is known to be "safe", as defined in <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>, then the request <em class="bcp14">MAY</em> be automatically redirected by the user agent without confirmation. Otherwise, the user agent <em class="bcp14">MUST NOT</em> automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which
     1339                  the request was issued.
     1340               </p>
     1341               <div class="note" id="rfc.section.8.3.2.p.4">
     1342                  <p><b>Note:</b> When automatically redirecting a POST request after receiving a 301 status code, some existing HTTP/1.0 user agents will erroneously
     1343                     change it into a GET request.
     1344                  </p>
     1345               </div>
     1346            </div>
     1347            <div id="status.302">
     1348               <div id="rfc.iref.3.3"></div>
     1349               <div id="rfc.iref.s.13"></div>
     1350               <h3 id="rfc.section.8.3.3"><a href="#rfc.section.8.3.3">8.3.3</a>&nbsp;<a href="#status.302">302 Found</a></h3>
     1351               <p id="rfc.section.8.3.3.p.1">The requested resource resides temporarily under a different URI. Since the redirection might be altered on occasion, the
     1352                  client <em class="bcp14">SHOULD</em> continue to use the Effectice Request URI for future requests. This response is only cacheable if indicated by a Cache-Control
     1353                  or Expires header field.
     1354               </p>
     1355               <p id="rfc.section.8.3.3.p.2">The temporary URI <em class="bcp14">SHOULD</em> be given by the Location field in the response. Unless the request method was HEAD, the entity of the response <em class="bcp14">SHOULD</em> contain a short hypertext note with a hyperlink to the new URI(s).
     1356               </p>
     1357               <p id="rfc.section.8.3.3.p.3">If the 302 status code is received in response to a request method that is known to be "safe", as defined in <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>, then the request <em class="bcp14">MAY</em> be automatically redirected by the user agent without confirmation. Otherwise, the user agent <em class="bcp14">MUST NOT</em> automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which
     1358                  the request was issued.
     1359               </p>
     1360               <div class="note" id="rfc.section.8.3.3.p.4">
     1361                  <p><b>Note:</b> HTTP/1.0 (<a href="#RFC1945" id="rfc.xref.RFC1945.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.0">[RFC1945]</cite></a>, <a href="https://tools.ietf.org/html/rfc1945#section-9.3">Section 9.3</a>) and the first version of HTTP/1.1 (<a href="#RFC2068" id="rfc.xref.RFC2068.2"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a>, <a href="https://tools.ietf.org/html/rfc2068#section-10.3.3">Section 10.3.3</a>) specify that the client is not allowed to change the method on the redirected request. However, most existing user agent
     1362                     implementations treat 302 as if it were a 303 response, performing a GET on the Location field-value regardless of the original
     1363                     request method. Therefore, a previous version of this specification (<a href="#RFC2616" id="rfc.xref.RFC2616.2"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, <a href="https://tools.ietf.org/html/rfc2616#section-10.3.3">Section 10.3.3</a>) has added the status codes <a href="#status.303" id="rfc.xref.status.303.2">303</a> and <a href="#status.307" id="rfc.xref.status.307.2">307</a> for servers that wish to make unambiguously clear which kind of reaction is expected of the client.
     1364                  </p>
     1365               </div>
     1366            </div>
     1367            <div id="status.303">
     1368               <div id="rfc.iref.3.4"></div>
     1369               <div id="rfc.iref.s.14"></div>
     1370               <h3 id="rfc.section.8.3.4"><a href="#rfc.section.8.3.4">8.3.4</a>&nbsp;<a href="#status.303">303 See Other</a></h3>
     1371               <p id="rfc.section.8.3.4.p.1">The server directs the user agent to a different resource, indicated by a URI in the Location header field, that provides
     1372                  an indirect response to the original request. The user agent <em class="bcp14">MAY</em> perform a GET request on the URI in the Location field in order to obtain a representation corresponding to the response,
     1373                  be redirected again, or end with an error status. The Location URI is not a substitute reference for the originally requested
     1374                  resource.
     1375               </p>
     1376               <p id="rfc.section.8.3.4.p.2">The 303 status is generally applicable to any HTTP method. It is primarily used to allow the output of a POST action to redirect
     1377                  the user agent to a selected resource, since doing so provides the information corresponding to the POST response in a form
     1378                  that can be separately identified, bookmarked, and cached independent of the original request.
     1379               </p>
     1380               <p id="rfc.section.8.3.4.p.3">A 303 response to a GET request indicates that the requested resource does not have a representation of its own that can be
     1381                  transferred by the server over HTTP. The Location URI indicates a resource that is descriptive of the requested resource such
     1382                  that the follow-on representation may be useful without implying that it adequately represents the previously requested resource.
     1383                  Note that answers to the questions of what can be represented, what representations are adequate, and what might be a useful
     1384                  description are outside the scope of HTTP and thus entirely determined by the URI owner(s).
     1385               </p>
     1386               <p id="rfc.section.8.3.4.p.4">A 303 response <em class="bcp14">SHOULD NOT</em> be cached unless it is indicated as cacheable by Cache-Control or Expires header fields. Except for responses to a HEAD request,
     1387                  the entity of a 303 response <em class="bcp14">SHOULD</em> contain a short hypertext note with a hyperlink to the Location URI.
     1388               </p>
     1389            </div>
     1390            <div id="status.304">
     1391               <div id="rfc.iref.3.5"></div>
     1392               <div id="rfc.iref.s.15"></div>
     1393               <h3 id="rfc.section.8.3.5"><a href="#rfc.section.8.3.5">8.3.5</a>&nbsp;<a href="#status.304">304 Not Modified</a></h3>
     1394               <p id="rfc.section.8.3.5.p.1">The response to the request has not been modified since the conditions indicated by the client's conditional GET request,
     1395                  as defined in <a href="p4-conditional.html#status.304" title="304 Not Modified">Section 3.1</a> of <a href="#Part4" id="rfc.xref.Part4.15"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
     1396               </p>
     1397            </div>
     1398            <div id="status.305">
     1399               <div id="rfc.iref.3.6"></div>
     1400               <div id="rfc.iref.s.16"></div>
     1401               <h3 id="rfc.section.8.3.6"><a href="#rfc.section.8.3.6">8.3.6</a>&nbsp;<a href="#status.305">305 Use Proxy</a></h3>
     1402               <p id="rfc.section.8.3.6.p.1">The 305 status was defined in a previous version of this specification (see <a href="#changes.from.rfc.2616" title="Changes from RFC 2616">Appendix&nbsp;A.2</a>), and is now deprecated.
     1403               </p>
     1404            </div>
     1405            <div id="status.306">
     1406               <div id="rfc.iref.3.7"></div>
     1407               <div id="rfc.iref.s.17"></div>
     1408               <h3 id="rfc.section.8.3.7"><a href="#rfc.section.8.3.7">8.3.7</a>&nbsp;<a href="#status.306">306 (Unused)</a></h3>
     1409               <p id="rfc.section.8.3.7.p.1">The 306 status code was used in a previous version of the specification, is no longer used, and the code is reserved.</p>
     1410            </div>
     1411            <div id="status.307">
     1412               <div id="rfc.iref.3.8"></div>
     1413               <div id="rfc.iref.s.18"></div>
     1414               <h3 id="rfc.section.8.3.8"><a href="#rfc.section.8.3.8">8.3.8</a>&nbsp;<a href="#status.307">307 Temporary Redirect</a></h3>
     1415               <p id="rfc.section.8.3.8.p.1">The requested resource resides temporarily under a different URI. Since the redirection <em class="bcp14">MAY</em> be altered on occasion, the client <em class="bcp14">SHOULD</em> continue to use the Effective Request URI for future requests. This response is only cacheable if indicated by a Cache-Control
     1416                  or Expires header field.
     1417               </p>
     1418               <p id="rfc.section.8.3.8.p.2">The temporary URI <em class="bcp14">SHOULD</em> be given by the Location field in the response. Unless the request method was HEAD, the entity of the response <em class="bcp14">SHOULD</em> contain a short hypertext note with a hyperlink to the new URI(s) , since many pre-HTTP/1.1 user agents do not understand
     1419                  the 307 status. Therefore, the note <em class="bcp14">SHOULD</em> contain the information necessary for a user to repeat the original request on the new URI.
     1420               </p>
     1421               <p id="rfc.section.8.3.8.p.3">If the 307 status code is received in response to a request method that is known to be "safe", as defined in <a href="#safe.methods" title="Safe Methods">Section&nbsp;7.1.1</a>, then the request <em class="bcp14">MAY</em> be automatically redirected by the user agent without confirmation. Otherwise, the user agent <em class="bcp14">MUST NOT</em> automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which
     1422                  the request was issued.
     1423               </p>
     1424            </div>
     1425         </div>
     1426         <div id="status.4xx">
     1427            <h2 id="rfc.section.8.4"><a href="#rfc.section.8.4">8.4</a>&nbsp;<a href="#status.4xx">Client Error 4xx</a></h2>
     1428            <p id="rfc.section.8.4.p.1">The 4xx class of status code is intended for cases in which the client seems to have erred. Except when responding to a HEAD
     1429               request, the server <em class="bcp14">SHOULD</em> include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition.
     1430               These status codes are applicable to any request method. User agents <em class="bcp14">SHOULD</em> display any included entity to the user.
     1431            </p>
     1432            <p id="rfc.section.8.4.p.2">If the client is sending data, a server implementation using TCP <em class="bcp14">SHOULD</em> be careful to ensure that the client acknowledges receipt of the packet(s) containing the response, before the server closes
     1433               the input connection. If the client continues sending data to the server after the close, the server's TCP stack will send
     1434               a reset packet to the client, which may erase the client's unacknowledged input buffers before they can be read and interpreted
     1435               by the HTTP application.
     1436            </p>
     1437            <div id="status.400">
     1438               <div id="rfc.iref.4.1"></div>
     1439               <div id="rfc.iref.s.19"></div>
     1440               <h3 id="rfc.section.8.4.1"><a href="#rfc.section.8.4.1">8.4.1</a>&nbsp;<a href="#status.400">400 Bad Request</a></h3>
     1441               <p id="rfc.section.8.4.1.p.1">The request could not be understood by the server due to malformed syntax. The client <em class="bcp14">SHOULD NOT</em> repeat the request without modifications.
     1442               </p>
     1443            </div>
     1444            <div id="status.401">
     1445               <div id="rfc.iref.4.2"></div>
     1446               <div id="rfc.iref.s.20"></div>
     1447               <h3 id="rfc.section.8.4.2"><a href="#rfc.section.8.4.2">8.4.2</a>&nbsp;<a href="#status.401">401 Unauthorized</a></h3>
     1448               <p id="rfc.section.8.4.2.p.1">The request requires user authentication (see <a href="p7-auth.html#status.401" title="401 Unauthorized">Section 2.1</a> of <a href="#Part7" id="rfc.xref.Part7.12"><cite title="HTTP/1.1, part 7: Authentication">[Part7]</cite></a>).
     1449               </p>
     1450            </div>
     1451            <div id="status.402">
     1452               <div id="rfc.iref.4.3"></div>
     1453               <div id="rfc.iref.s.21"></div>
     1454               <h3 id="rfc.section.8.4.3"><a href="#rfc.section.8.4.3">8.4.3</a>&nbsp;<a href="#status.402">402 Payment Required</a></h3>
     1455               <p id="rfc.section.8.4.3.p.1">This code is reserved for future use.</p>
     1456            </div>
     1457            <div id="status.403">
     1458               <div id="rfc.iref.4.4"></div>
     1459               <div id="rfc.iref.s.22"></div>
     1460               <h3 id="rfc.section.8.4.4"><a href="#rfc.section.8.4.4">8.4.4</a>&nbsp;<a href="#status.403">403 Forbidden</a></h3>
     1461               <p id="rfc.section.8.4.4.p.1">The server understood the request, but is refusing to fulfill it. Authorization will not help and the request <em class="bcp14">SHOULD NOT</em> be repeated. If the request method was not HEAD and the server wishes to make public why the request has not been fulfilled,
     1462                  it <em class="bcp14">SHOULD</em> describe the reason for the refusal in the entity. If the server does not wish to make this information available to the client,
     1463                  the status code 404 (Not Found) can be used instead.
     1464               </p>
     1465            </div>
     1466            <div id="status.404">
     1467               <div id="rfc.iref.4.5"></div>
     1468               <div id="rfc.iref.s.23"></div>
     1469               <h3 id="rfc.section.8.4.5"><a href="#rfc.section.8.4.5">8.4.5</a>&nbsp;<a href="#status.404">404 Not Found</a></h3>
     1470               <p id="rfc.section.8.4.5.p.1">The server has not found anything matching the Effective Request URI. No indication is given of whether the condition is temporary
     1471                  or permanent. The 410 (Gone) status code <em class="bcp14">SHOULD</em> be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable
     1472                  and has no forwarding address. This status code is commonly used when the server does not wish to reveal exactly why the request
     1473                  has been refused, or when no other response is applicable.
     1474               </p>
     1475            </div>
     1476            <div id="status.405">
     1477               <div id="rfc.iref.4.6"></div>
     1478               <div id="rfc.iref.s.24"></div>
     1479               <h3 id="rfc.section.8.4.6"><a href="#rfc.section.8.4.6">8.4.6</a>&nbsp;<a href="#status.405">405 Method Not Allowed</a></h3>
     1480               <p id="rfc.section.8.4.6.p.1">The method specified in the Request-Line is not allowed for the resource identified by the Effective Request URI. The response <em class="bcp14">MUST</em> include an Allow header containing a list of valid methods for the requested resource.
     1481               </p>
     1482            </div>
     1483            <div id="status.406">
     1484               <div id="rfc.iref.4.7"></div>
     1485               <div id="rfc.iref.s.25"></div>
     1486               <h3 id="rfc.section.8.4.7"><a href="#rfc.section.8.4.7">8.4.7</a>&nbsp;<a href="#status.406">406 Not Acceptable</a></h3>
     1487               <p id="rfc.section.8.4.7.p.1">The resource identified by the request is only capable of generating response entities which have content characteristics
     1488                  not acceptable according to the accept headers sent in the request.
     1489               </p>
     1490               <p id="rfc.section.8.4.7.p.2">Unless it was a HEAD request, the response <em class="bcp14">SHOULD</em> include an entity containing a list of available entity characteristics and location(s) from which the user or user agent
     1491                  can choose the one most appropriate. The entity format is specified by the media type given in the Content-Type header field.
     1492                  Depending upon the format and the capabilities of the user agent, selection of the most appropriate choice <em class="bcp14">MAY</em> be performed automatically. However, this specification does not define any standard for such automatic selection.
     1493               </p>
     1494               <div class="note" id="rfc.section.8.4.7.p.3">
     1495                  <p><b>Note:</b> HTTP/1.1 servers are allowed to return responses which are not acceptable according to the accept headers sent in the request.
     1496                     In some cases, this may even be preferable to sending a 406 response. User agents are encouraged to inspect the headers of
     1497                     an incoming response to determine if it is acceptable.
     1498                  </p>
     1499               </div>
     1500               <p id="rfc.section.8.4.7.p.4">If the response could be unacceptable, a user agent <em class="bcp14">SHOULD</em> temporarily stop receipt of more data and query the user for a decision on further actions.
     1501               </p>
     1502            </div>
     1503            <div id="status.407">
     1504               <div id="rfc.iref.4.8"></div>
     1505               <div id="rfc.iref.s.26"></div>
     1506               <h3 id="rfc.section.8.4.8"><a href="#rfc.section.8.4.8">8.4.8</a>&nbsp;<a href="#status.407">407 Proxy Authentication Required</a></h3>
     1507               <p id="rfc.section.8.4.8.p.1">This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy (see <a href="p7-auth.html#status.407" title="407 Proxy Authentication Required">Section 2.2</a> of <a href="#Part7" id="rfc.xref.Part7.13"><cite title="HTTP/1.1, part 7: Authentication">[Part7]</cite></a>).
     1508               </p>
     1509            </div>
     1510            <div id="status.408">
     1511               <div id="rfc.iref.4.9"></div>
     1512               <div id="rfc.iref.s.27"></div>
     1513               <h3 id="rfc.section.8.4.9"><a href="#rfc.section.8.4.9">8.4.9</a>&nbsp;<a href="#status.408">408 Request Timeout</a></h3>
     1514               <p id="rfc.section.8.4.9.p.1">The client did not produce a request within the time that the server was prepared to wait. The client <em class="bcp14">MAY</em> repeat the request without modifications at any later time.
     1515               </p>
     1516            </div>
     1517            <div id="status.409">
     1518               <div id="rfc.iref.4.10"></div>
     1519               <div id="rfc.iref.s.28"></div>
     1520               <h3 id="rfc.section.8.4.10"><a href="#rfc.section.8.4.10">8.4.10</a>&nbsp;<a href="#status.409">409 Conflict</a></h3>
     1521               <p id="rfc.section.8.4.10.p.1">The request could not be completed due to a conflict with the current state of the resource. This code is only allowed in
     1522                  situations where it is expected that the user might be able to resolve the conflict and resubmit the request. The response
     1523                  body <em class="bcp14">SHOULD</em> include enough information for the user to recognize the source of the conflict. Ideally, the response entity would include
     1524                  enough information for the user or user agent to fix the problem; however, that might not be possible and is not required.
     1525               </p>
     1526               <p id="rfc.section.8.4.10.p.2">Conflicts are most likely to occur in response to a PUT request. For example, if versioning were being used and the entity
     1527                  being PUT included changes to a resource which conflict with those made by an earlier (third-party) request, the server might
     1528                  use the 409 response to indicate that it can't complete the request. In this case, the response entity would likely contain
     1529                  a list of the differences between the two versions in a format defined by the response Content-Type.
     1530               </p>
     1531            </div>
     1532            <div id="status.410">
     1533               <div id="rfc.iref.4.11"></div>
     1534               <div id="rfc.iref.s.29"></div>
     1535               <h3 id="rfc.section.8.4.11"><a href="#rfc.section.8.4.11">8.4.11</a>&nbsp;<a href="#status.410">410 Gone</a></h3>
     1536               <p id="rfc.section.8.4.11.p.1">The requested resource is no longer available at the server and no forwarding address is known. This condition is expected
     1537                  to be considered permanent. Clients with link editing capabilities <em class="bcp14">SHOULD</em> delete references to the Effective Request URI after user approval. If the server does not know, or has no facility to determine,
     1538                  whether or not the condition is permanent, the status code 404 (Not Found) <em class="bcp14">SHOULD</em> be used instead. This response is cacheable unless indicated otherwise.
     1539               </p>
     1540               <p id="rfc.section.8.4.11.p.2">The 410 response is primarily intended to assist the task of web maintenance by notifying the recipient that the resource
     1541                  is intentionally unavailable and that the server owners desire that remote links to that resource be removed. Such an event
     1542                  is common for limited-time, promotional services and for resources belonging to individuals no longer working at the server's
     1543                  site. It is not necessary to mark all permanently unavailable resources as "gone" or to keep the mark for any length of time
     1544                  -- that is left to the discretion of the server owner.
     1545               </p>
     1546            </div>
     1547            <div id="status.411">
     1548               <div id="rfc.iref.4.12"></div>
     1549               <div id="rfc.iref.s.30"></div>
     1550               <h3 id="rfc.section.8.4.12"><a href="#rfc.section.8.4.12">8.4.12</a>&nbsp;<a href="#status.411">411 Length Required</a></h3>
     1551               <p id="rfc.section.8.4.12.p.1">The server refuses to accept the request without a defined Content-Length. The client <em class="bcp14">MAY</em> repeat the request if it adds a valid Content-Length header field containing the length of the message-body in the request
     1552                  message.
     1553               </p>
     1554            </div>
     1555            <div id="status.412">
     1556               <div id="rfc.iref.4.13"></div>
     1557               <div id="rfc.iref.s.31"></div>
     1558               <h3 id="rfc.section.8.4.13"><a href="#rfc.section.8.4.13">8.4.13</a>&nbsp;<a href="#status.412">412 Precondition Failed</a></h3>
     1559               <p id="rfc.section.8.4.13.p.1">The precondition given in one or more of the request-header fields evaluated to false when it was tested on the server, as
     1560                  defined in <a href="p4-conditional.html#status.412" title="412 Precondition Failed">Section 3.2</a> of <a href="#Part4" id="rfc.xref.Part4.16"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
     1561               </p>
     1562            </div>
     1563            <div id="status.413">
     1564               <div id="rfc.iref.4.14"></div>
     1565               <div id="rfc.iref.s.32"></div>
     1566               <h3 id="rfc.section.8.4.14"><a href="#rfc.section.8.4.14">8.4.14</a>&nbsp;<a href="#status.413">413 Request Entity Too Large</a></h3>
     1567               <p id="rfc.section.8.4.14.p.1">The server is refusing to process a request because the request entity is larger than the server is willing or able to process.
     1568                  The server <em class="bcp14">MAY</em> close the connection to prevent the client from continuing the request.
     1569               </p>
     1570               <p id="rfc.section.8.4.14.p.2">If the condition is temporary, the server <em class="bcp14">SHOULD</em> include a Retry-After header field to indicate that it is temporary and after what time the client <em class="bcp14">MAY</em> try again.
     1571               </p>
     1572            </div>
     1573            <div id="status.414">
     1574               <div id="rfc.iref.4.15"></div>
     1575               <div id="rfc.iref.s.33"></div>
     1576               <h3 id="rfc.section.8.4.15"><a href="#rfc.section.8.4.15">8.4.15</a>&nbsp;<a href="#status.414">414 URI Too Long</a></h3>
     1577               <p id="rfc.section.8.4.15.p.1">The server is refusing to service the request because the Effective Request URI is longer than the server is willing to interpret.
     1578                  This rare condition is only likely to occur when a client has improperly converted a POST request to a GET request with long
     1579                  query information, when the client has descended into a URI "black hole" of redirection (e.g., a redirected URI prefix that
     1580                  points to a suffix of itself), or when the server is under attack by a client attempting to exploit security holes present
     1581                  in some servers using fixed-length buffers for reading or manipulating the Effective Request URI.
     1582               </p>
     1583            </div>
     1584            <div id="status.415">
     1585               <div id="rfc.iref.4.16"></div>
     1586               <div id="rfc.iref.s.34"></div>
     1587               <h3 id="rfc.section.8.4.16"><a href="#rfc.section.8.4.16">8.4.16</a>&nbsp;<a href="#status.415">415 Unsupported Media Type</a></h3>
     1588               <p id="rfc.section.8.4.16.p.1">The server is refusing to service the request because the entity of the request is in a format not supported by the requested
     1589                  resource for the requested method.
     1590               </p>
     1591            </div>
     1592            <div id="status.416">
     1593               <div id="rfc.iref.4.17"></div>
     1594               <div id="rfc.iref.s.35"></div>
     1595               <h3 id="rfc.section.8.4.17"><a href="#rfc.section.8.4.17">8.4.17</a>&nbsp;<a href="#status.416">416 Requested Range Not Satisfiable</a></h3>
     1596               <p id="rfc.section.8.4.17.p.1">The request included a Range request-header field (<a href="p5-range.html#header.range" title="Range">Section 5.4</a> of <a href="#Part5" id="rfc.xref.Part5.12"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>) and none of the range-specifier values in this field overlap the current extent of the selected resource. See <a href="p5-range.html#status.416" title="416 Requested Range Not Satisfiable">Section 3.2</a> of <a href="#Part5" id="rfc.xref.Part5.13"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>
     1597               </p>
     1598            </div>
     1599            <div id="status.417">
     1600               <div id="rfc.iref.4.18"></div>
     1601               <div id="rfc.iref.s.36"></div>
     1602               <h3 id="rfc.section.8.4.18"><a href="#rfc.section.8.4.18">8.4.18</a>&nbsp;<a href="#status.417">417 Expectation Failed</a></h3>
     1603               <p id="rfc.section.8.4.18.p.1">The expectation given in an Expect request-header field (see <a href="#header.expect" id="rfc.xref.header.expect.2" title="Expect">Section&nbsp;9.2</a>) could not be met by this server, or, if the server is a proxy, the server has unambiguous evidence that the request could
     1604                  not be met by the next-hop server.
     1605               </p>
     1606            </div>
     1607         </div>
     1608         <div id="status.5xx">
     1609            <h2 id="rfc.section.8.5"><a href="#rfc.section.8.5">8.5</a>&nbsp;<a href="#status.5xx">Server Error 5xx</a></h2>
     1610            <p id="rfc.section.8.5.p.1">Response status codes beginning with the digit "5" indicate cases in which the server is aware that it has erred or is incapable
     1611               of performing the request. Except when responding to a HEAD request, the server <em class="bcp14">SHOULD</em> include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition.
     1612               User agents <em class="bcp14">SHOULD</em> display any included entity to the user. These response codes are applicable to any request method.
     1613            </p>
     1614            <div id="status.500">
     1615               <div id="rfc.iref.5.1"></div>
     1616               <div id="rfc.iref.s.37"></div>
     1617               <h3 id="rfc.section.8.5.1"><a href="#rfc.section.8.5.1">8.5.1</a>&nbsp;<a href="#status.500">500 Internal Server Error</a></h3>
     1618               <p id="rfc.section.8.5.1.p.1">The server encountered an unexpected condition which prevented it from fulfilling the request.</p>
     1619            </div>
     1620            <div id="status.501">
     1621               <div id="rfc.iref.5.2"></div>
     1622               <div id="rfc.iref.s.38"></div>
     1623               <h3 id="rfc.section.8.5.2"><a href="#rfc.section.8.5.2">8.5.2</a>&nbsp;<a href="#status.501">501 Not Implemented</a></h3>
     1624               <p id="rfc.section.8.5.2.p.1">The server does not support the functionality required to fulfill the request. This is the appropriate response when the server
     1625                  does not recognize the request method and is not capable of supporting it for any resource.
     1626               </p>
     1627            </div>
     1628            <div id="status.502">
     1629               <div id="rfc.iref.5.3"></div>
     1630               <div id="rfc.iref.s.39"></div>
     1631               <h3 id="rfc.section.8.5.3"><a href="#rfc.section.8.5.3">8.5.3</a>&nbsp;<a href="#status.502">502 Bad Gateway</a></h3>
     1632               <p id="rfc.section.8.5.3.p.1">The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting
     1633                  to fulfill the request.
     1634               </p>
     1635            </div>
     1636            <div id="status.503">
     1637               <div id="rfc.iref.5.4"></div>
     1638               <div id="rfc.iref.s.40"></div>
     1639               <h3 id="rfc.section.8.5.4"><a href="#rfc.section.8.5.4">8.5.4</a>&nbsp;<a href="#status.503">503 Service Unavailable</a></h3>
     1640               <p id="rfc.section.8.5.4.p.1">The server is currently unable to handle the request due to a temporary overloading or maintenance of the server. The implication
     1641                  is that this is a temporary condition which will be alleviated after some delay. If known, the length of the delay <em class="bcp14">MAY</em> be indicated in a Retry-After header. If no Retry-After is given, the client <em class="bcp14">SHOULD</em> handle the response as it would for a 500 response.
     1642               </p>
     1643               <div class="note" id="rfc.section.8.5.4.p.2">
     1644                  <p><b>Note:</b> The existence of the 503 status code does not imply that a server must use it when becoming overloaded. Some servers may wish
     1645                     to simply refuse the connection.
     1646                  </p>
     1647               </div>
     1648            </div>
     1649            <div id="status.504">
     1650               <div id="rfc.iref.5.5"></div>
     1651               <div id="rfc.iref.s.41"></div>
     1652               <h3 id="rfc.section.8.5.5"><a href="#rfc.section.8.5.5">8.5.5</a>&nbsp;<a href="#status.504">504 Gateway Timeout</a></h3>
     1653               <p id="rfc.section.8.5.5.p.1">The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the
     1654                  URI (e.g., HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed to access in attempting to complete the request.
     1655               </p>
     1656               <div class="note" id="rfc.section.8.5.5.p.2">
     1657                  <p><b>Note</b> to implementors: some deployed proxies are known to return 400 or 500 when DNS lookups time out.
     1658                  </p>
     1659               </div>
     1660            </div>
     1661            <div id="status.505">
     1662               <div id="rfc.iref.5.6"></div>
     1663               <div id="rfc.iref.s.42"></div>
     1664               <h3 id="rfc.section.8.5.6"><a href="#rfc.section.8.5.6">8.5.6</a>&nbsp;<a href="#status.505">505 HTTP Version Not Supported</a></h3>
     1665               <p id="rfc.section.8.5.6.p.1">The server does not support, or refuses to support, the protocol version that was used in the request message. The server
     1666                  is indicating that it is unable or unwilling to complete the request using the same major version as the client, as described
     1667                  in <a href="p1-messaging.html#http.version" title="HTTP Version">Section 2.5</a> of <a href="#Part1" id="rfc.xref.Part1.27"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, other than with this error message. The response <em class="bcp14">SHOULD</em> contain an entity describing why that version is not supported and what other protocols are supported by that server.
     1668               </p>
     1669            </div>
     1670         </div>
    13811671      </div>
    1382       <p id="rfc.section.8.4.7.p.4">If the response could be unacceptable, a user agent <em class="bcp14">SHOULD</em> temporarily stop receipt of more data and query the user for a decision on further actions.
    1383       </p>
    1384       <div id="rfc.iref.49"></div>
    1385       <div id="rfc.iref.s.26"></div>
    1386       <h3 id="rfc.section.8.4.8"><a href="#rfc.section.8.4.8">8.4.8</a>&nbsp;<a id="status.407" href="#status.407">407 Proxy Authentication Required</a></h3>
    1387       <p id="rfc.section.8.4.8.p.1">This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy (see <a href="p7-auth.html#status.407" title="407 Proxy Authentication Required">Section 2.2</a> of <a href="#Part7" id="rfc.xref.Part7.13"><cite title="HTTP/1.1, part 7: Authentication">[Part7]</cite></a>).
    1388       </p>
    1389       <div id="rfc.iref.50"></div>
    1390       <div id="rfc.iref.s.27"></div>
    1391       <h3 id="rfc.section.8.4.9"><a href="#rfc.section.8.4.9">8.4.9</a>&nbsp;<a id="status.408" href="#status.408">408 Request Timeout</a></h3>
    1392       <p id="rfc.section.8.4.9.p.1">The client did not produce a request within the time that the server was prepared to wait. The client <em class="bcp14">MAY</em> repeat the request without modifications at any later time.
    1393       </p>
    1394       <div id="rfc.iref.51"></div>
    1395       <div id="rfc.iref.s.28"></div>
    1396       <h3 id="rfc.section.8.4.10"><a href="#rfc.section.8.4.10">8.4.10</a>&nbsp;<a id="status.409" href="#status.409">409 Conflict</a></h3>
    1397       <p id="rfc.section.8.4.10.p.1">The request could not be completed due to a conflict with the current state of the resource. This code is only allowed in
    1398          situations where it is expected that the user might be able to resolve the conflict and resubmit the request. The response
    1399          body <em class="bcp14">SHOULD</em> include enough information for the user to recognize the source of the conflict. Ideally, the response entity would include
    1400          enough information for the user or user agent to fix the problem; however, that might not be possible and is not required.
    1401       </p>
    1402       <p id="rfc.section.8.4.10.p.2">Conflicts are most likely to occur in response to a PUT request. For example, if versioning were being used and the entity
    1403          being PUT included changes to a resource which conflict with those made by an earlier (third-party) request, the server might
    1404          use the 409 response to indicate that it can't complete the request. In this case, the response entity would likely contain
    1405          a list of the differences between the two versions in a format defined by the response Content-Type.
    1406       </p>
    1407       <div id="rfc.iref.52"></div>
    1408       <div id="rfc.iref.s.29"></div>
    1409       <h3 id="rfc.section.8.4.11"><a href="#rfc.section.8.4.11">8.4.11</a>&nbsp;<a id="status.410" href="#status.410">410 Gone</a></h3>
    1410       <p id="rfc.section.8.4.11.p.1">The requested resource is no longer available at the server and no forwarding address is known. This condition is expected
    1411          to be considered permanent. Clients with link editing capabilities <em class="bcp14">SHOULD</em> delete references to the Effective Request URI after user approval. If the server does not know, or has no facility to determine,
    1412          whether or not the condition is permanent, the status code 404 (Not Found) <em class="bcp14">SHOULD</em> be used instead. This response is cacheable unless indicated otherwise.
    1413       </p>
    1414       <p id="rfc.section.8.4.11.p.2">The 410 response is primarily intended to assist the task of web maintenance by notifying the recipient that the resource
    1415          is intentionally unavailable and that the server owners desire that remote links to that resource be removed. Such an event
    1416          is common for limited-time, promotional services and for resources belonging to individuals no longer working at the server's
    1417          site. It is not necessary to mark all permanently unavailable resources as "gone" or to keep the mark for any length of time
    1418          -- that is left to the discretion of the server owner.
    1419       </p>
    1420       <div id="rfc.iref.53"></div>
    1421       <div id="rfc.iref.s.30"></div>
    1422       <h3 id="rfc.section.8.4.12"><a href="#rfc.section.8.4.12">8.4.12</a>&nbsp;<a id="status.411" href="#status.411">411 Length Required</a></h3>
    1423       <p id="rfc.section.8.4.12.p.1">The server refuses to accept the request without a defined Content-Length. The client <em class="bcp14">MAY</em> repeat the request if it adds a valid Content-Length header field containing the length of the message-body in the request
    1424          message.
    1425       </p>
    1426       <div id="rfc.iref.54"></div>
    1427       <div id="rfc.iref.s.31"></div>
    1428       <h3 id="rfc.section.8.4.13"><a href="#rfc.section.8.4.13">8.4.13</a>&nbsp;<a id="status.412" href="#status.412">412 Precondition Failed</a></h3>
    1429       <p id="rfc.section.8.4.13.p.1">The precondition given in one or more of the request-header fields evaluated to false when it was tested on the server, as
    1430          defined in <a href="p4-conditional.html#status.412" title="412 Precondition Failed">Section 3.2</a> of <a href="#Part4" id="rfc.xref.Part4.16"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
    1431       </p>
    1432       <div id="rfc.iref.55"></div>
    1433       <div id="rfc.iref.s.32"></div>
    1434       <h3 id="rfc.section.8.4.14"><a href="#rfc.section.8.4.14">8.4.14</a>&nbsp;<a id="status.413" href="#status.413">413 Request Entity Too Large</a></h3>
    1435       <p id="rfc.section.8.4.14.p.1">The server is refusing to process a request because the request entity is larger than the server is willing or able to process.
    1436          The server <em class="bcp14">MAY</em> close the connection to prevent the client from continuing the request.
    1437       </p>
    1438       <p id="rfc.section.8.4.14.p.2">If the condition is temporary, the server <em class="bcp14">SHOULD</em> include a Retry-After header field to indicate that it is temporary and after what time the client <em class="bcp14">MAY</em> try again.
    1439       </p>
    1440       <div id="rfc.iref.56"></div>
    1441       <div id="rfc.iref.s.33"></div>
    1442       <h3 id="rfc.section.8.4.15"><a href="#rfc.section.8.4.15">8.4.15</a>&nbsp;<a id="status.414" href="#status.414">414 URI Too Long</a></h3>
    1443       <p id="rfc.section.8.4.15.p.1">The server is refusing to service the request because the Effective Request URI is longer than the server is willing to interpret.
    1444          This rare condition is only likely to occur when a client has improperly converted a POST request to a GET request with long
    1445          query information, when the client has descended into a URI "black hole" of redirection (e.g., a redirected URI prefix that
    1446          points to a suffix of itself), or when the server is under attack by a client attempting to exploit security holes present
    1447          in some servers using fixed-length buffers for reading or manipulating the Effective Request URI.
    1448       </p>
    1449       <div id="rfc.iref.57"></div>
    1450       <div id="rfc.iref.s.34"></div>
    1451       <h3 id="rfc.section.8.4.16"><a href="#rfc.section.8.4.16">8.4.16</a>&nbsp;<a id="status.415" href="#status.415">415 Unsupported Media Type</a></h3>
    1452       <p id="rfc.section.8.4.16.p.1">The server is refusing to service the request because the entity of the request is in a format not supported by the requested
    1453          resource for the requested method.
    1454       </p>
    1455       <div id="rfc.iref.58"></div>
    1456       <div id="rfc.iref.s.35"></div>
    1457       <h3 id="rfc.section.8.4.17"><a href="#rfc.section.8.4.17">8.4.17</a>&nbsp;<a id="status.416" href="#status.416">416 Requested Range Not Satisfiable</a></h3>
    1458       <p id="rfc.section.8.4.17.p.1">The request included a Range request-header field (<a href="p5-range.html#header.range" title="Range">Section 5.4</a> of <a href="#Part5" id="rfc.xref.Part5.12"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>) and none of the range-specifier values in this field overlap the current extent of the selected resource. See <a href="p5-range.html#status.416" title="416 Requested Range Not Satisfiable">Section 3.2</a> of <a href="#Part5" id="rfc.xref.Part5.13"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>
    1459       </p>
    1460       <div id="rfc.iref.59"></div>
    1461       <div id="rfc.iref.s.36"></div>
    1462       <h3 id="rfc.section.8.4.18"><a href="#rfc.section.8.4.18">8.4.18</a>&nbsp;<a id="status.417" href="#status.417">417 Expectation Failed</a></h3>
    1463       <p id="rfc.section.8.4.18.p.1">The expectation given in an Expect request-header field (see <a href="#header.expect" id="rfc.xref.header.expect.2" title="Expect">Section&nbsp;9.2</a>) could not be met by this server, or, if the server is a proxy, the server has unambiguous evidence that the request could
    1464          not be met by the next-hop server.
    1465       </p>
    1466       <h2 id="rfc.section.8.5"><a href="#rfc.section.8.5">8.5</a>&nbsp;<a id="status.5xx" href="#status.5xx">Server Error 5xx</a></h2>
    1467       <p id="rfc.section.8.5.p.1">Response status codes beginning with the digit "5" indicate cases in which the server is aware that it has erred or is incapable
    1468          of performing the request. Except when responding to a HEAD request, the server <em class="bcp14">SHOULD</em> include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition.
    1469          User agents <em class="bcp14">SHOULD</em> display any included entity to the user. These response codes are applicable to any request method.
    1470       </p>
    1471       <div id="rfc.iref.60"></div>
    1472       <div id="rfc.iref.s.37"></div>
    1473       <h3 id="rfc.section.8.5.1"><a href="#rfc.section.8.5.1">8.5.1</a>&nbsp;<a id="status.500" href="#status.500">500 Internal Server Error</a></h3>
    1474       <p id="rfc.section.8.5.1.p.1">The server encountered an unexpected condition which prevented it from fulfilling the request.</p>
    1475       <div id="rfc.iref.61"></div>
    1476       <div id="rfc.iref.s.38"></div>
    1477       <h3 id="rfc.section.8.5.2"><a href="#rfc.section.8.5.2">8.5.2</a>&nbsp;<a id="status.501" href="#status.501">501 Not Implemented</a></h3>
    1478       <p id="rfc.section.8.5.2.p.1">The server does not support the functionality required to fulfill the request. This is the appropriate response when the server
    1479          does not recognize the request method and is not capable of supporting it for any resource.
    1480       </p>
    1481       <div id="rfc.iref.62"></div>
    1482       <div id="rfc.iref.s.39"></div>
    1483       <h3 id="rfc.section.8.5.3"><a href="#rfc.section.8.5.3">8.5.3</a>&nbsp;<a id="status.502" href="#status.502">502 Bad Gateway</a></h3>
    1484       <p id="rfc.section.8.5.3.p.1">The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting
    1485          to fulfill the request.
    1486       </p>
    1487       <div id="rfc.iref.63"></div>
    1488       <div id="rfc.iref.s.40"></div>
    1489       <h3 id="rfc.section.8.5.4"><a href="#rfc.section.8.5.4">8.5.4</a>&nbsp;<a id="status.503" href="#status.503">503 Service Unavailable</a></h3>
    1490       <p id="rfc.section.8.5.4.p.1">The server is currently unable to handle the request due to a temporary overloading or maintenance of the server. The implication
    1491          is that this is a temporary condition which will be alleviated after some delay. If known, the length of the delay <em class="bcp14">MAY</em> be indicated in a Retry-After header. If no Retry-After is given, the client <em class="bcp14">SHOULD</em> handle the response as it would for a 500 response.
    1492       </p>
    1493       <div class="note" id="rfc.section.8.5.4.p.2">
    1494          <p> <b>Note:</b> The existence of the 503 status code does not imply that a server must use it when becoming overloaded. Some servers may wish
    1495             to simply refuse the connection.
    1496          </p>
    1497       </div>
    1498       <div id="rfc.iref.64"></div>
    1499       <div id="rfc.iref.s.41"></div>
    1500       <h3 id="rfc.section.8.5.5"><a href="#rfc.section.8.5.5">8.5.5</a>&nbsp;<a id="status.504" href="#status.504">504 Gateway Timeout</a></h3>
    1501       <p id="rfc.section.8.5.5.p.1">The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the
    1502          URI (e.g., HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed to access in attempting to complete the request.
    1503       </p>
    1504       <div class="note" id="rfc.section.8.5.5.p.2">
    1505          <p> <b>Note</b> to implementors: some deployed proxies are known to return 400 or 500 when DNS lookups time out.
    1506          </p>
    1507       </div>
    1508       <div id="rfc.iref.65"></div>
    1509       <div id="rfc.iref.s.42"></div>
    1510       <h3 id="rfc.section.8.5.6"><a href="#rfc.section.8.5.6">8.5.6</a>&nbsp;<a id="status.505" href="#status.505">505 HTTP Version Not Supported</a></h3>
    1511       <p id="rfc.section.8.5.6.p.1">The server does not support, or refuses to support, the protocol version that was used in the request message. The server
    1512          is indicating that it is unable or unwilling to complete the request using the same major version as the client, as described
    1513          in <a href="p1-messaging.html#http.version" title="HTTP Version">Section 2.5</a> of <a href="#Part1" id="rfc.xref.Part1.27"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, other than with this error message. The response <em class="bcp14">SHOULD</em> contain an entity describing why that version is not supported and what other protocols are supported by that server.
    1514       </p>
    1515       <h1 id="rfc.section.9"><a href="#rfc.section.9">9.</a>&nbsp;<a id="header.fields" href="#header.fields">Header Field Definitions</a></h1>
    1516       <p id="rfc.section.9.p.1">This section defines the syntax and semantics of HTTP/1.1 header fields related to request and response semantics.</p>
    1517       <p id="rfc.section.9.p.2">For entity-header fields, both sender and recipient refer to either the client or the server, depending on who sends and who
    1518          receives the entity.
    1519       </p>
    1520       <div id="rfc.iref.a.1"></div>
    1521       <div id="rfc.iref.h.2"></div>
    1522       <h2 id="rfc.section.9.1"><a href="#rfc.section.9.1">9.1</a>&nbsp;<a id="header.allow" href="#header.allow">Allow</a></h2>
    1523       <p id="rfc.section.9.1.p.1">The "Allow" response-header field lists the set of methods advertised as supported by the resource identified by the Effective
    1524          Request URI. The purpose of this field is strictly to inform the recipient of valid methods associated with the resource.
    1525       </p>
    1526       <div id="rfc.figure.u.12"></div><pre class="inline"><span id="rfc.iref.g.9"></span><span id="rfc.iref.g.10"></span>  <a href="#header.allow" class="smpl">Allow</a>   = "Allow" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.allow" class="smpl">Allow-v</a>
     1672      <div id="header.fields">
     1673         <h1 id="rfc.section.9"><a href="#rfc.section.9">9.</a>&nbsp;<a href="#header.fields">Header Field Definitions</a></h1>
     1674         <p id="rfc.section.9.p.1">This section defines the syntax and semantics of HTTP/1.1 header fields related to request and response semantics.</p>
     1675         <p id="rfc.section.9.p.2">For entity-header fields, both sender and recipient refer to either the client or the server, depending on who sends and who
     1676            receives the entity.
     1677         </p>
     1678         <div id="header.allow">
     1679            <div id="rfc.iref.a.1"></div>
     1680            <div id="rfc.iref.h.2"></div>
     1681            <h2 id="rfc.section.9.1"><a href="#rfc.section.9.1">9.1</a>&nbsp;<a href="#header.allow">Allow</a></h2>
     1682            <p id="rfc.section.9.1.p.1">The "Allow" response-header field lists the set of methods advertised as supported by the resource identified by the Effective
     1683               Request URI. The purpose of this field is strictly to inform the recipient of valid methods associated with the resource.
     1684            </p>
     1685            <div id="rfc.figure.u.12"></div><pre class="inline"><span id="rfc.iref.g.9"></span><span id="rfc.iref.g.10"></span>  <a href="#header.allow" class="smpl">Allow</a>   = "Allow" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.allow" class="smpl">Allow-v</a>
    15271686  <a href="#header.allow" class="smpl">Allow-v</a> = #<a href="#method" class="smpl">Method</a>
    15281687</pre><p id="rfc.section.9.1.p.3">Example of use:</p>
    1529       <div id="rfc.figure.u.13"></div><pre class="text">  Allow: GET, HEAD, PUT
     1688            <div id="rfc.figure.u.13"></div><pre class="text">  Allow: GET, HEAD, PUT
    15301689</pre><p id="rfc.section.9.1.p.5">The actual set of allowed methods is defined by the origin server at the time of each request.</p>
    1531       <p id="rfc.section.9.1.p.6">A proxy <em class="bcp14">MUST NOT</em> modify the Allow header field even if it does not understand all the methods specified, since the user agent might have other
    1532          means of communicating with the origin server.
    1533       </p>
    1534       <div id="rfc.iref.e.1"></div>
    1535       <div id="rfc.iref.h.3"></div>
    1536       <h2 id="rfc.section.9.2"><a href="#rfc.section.9.2">9.2</a>&nbsp;<a id="header.expect" href="#header.expect">Expect</a></h2>
    1537       <p id="rfc.section.9.2.p.1">The "Expect" request-header field is used to indicate that particular server behaviors are required by the client.</p>
    1538       <div id="rfc.figure.u.14"></div><pre class="inline"><span id="rfc.iref.g.11"></span><span id="rfc.iref.g.12"></span><span id="rfc.iref.g.13"></span><span id="rfc.iref.g.14"></span><span id="rfc.iref.g.15"></span>  <a href="#header.expect" class="smpl">Expect</a>       = "Expect" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.expect" class="smpl">Expect-v</a>
     1690            <p id="rfc.section.9.1.p.6">A proxy <em class="bcp14">MUST NOT</em> modify the Allow header field even if it does not understand all the methods specified, since the user agent might have other
     1691               means of communicating with the origin server.
     1692            </p>
     1693         </div>
     1694         <div id="header.expect">
     1695            <div id="rfc.iref.e.1"></div>
     1696            <div id="rfc.iref.h.3"></div>
     1697            <h2 id="rfc.section.9.2"><a href="#rfc.section.9.2">9.2</a>&nbsp;<a href="#header.expect">Expect</a></h2>
     1698            <p id="rfc.section.9.2.p.1">The "Expect" request-header field is used to indicate that particular server behaviors are required by the client.</p>
     1699            <div id="rfc.figure.u.14"></div><pre class="inline"><span id="rfc.iref.g.11"></span><span id="rfc.iref.g.12"></span><span id="rfc.iref.g.13"></span><span id="rfc.iref.g.14"></span><span id="rfc.iref.g.15"></span>  <a href="#header.expect" class="smpl">Expect</a>       = "Expect" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.expect" class="smpl">Expect-v</a>
    15391700  <a href="#header.expect" class="smpl">Expect-v</a>     = 1#<a href="#header.expect" class="smpl">expectation</a>
    15401701 
    … …  
    15441705  <a href="#header.expect" class="smpl">expect-params</a> = ";" <a href="#core.rules" class="smpl">token</a> [ "=" ( <a href="#core.rules" class="smpl">token</a> / <a href="#core.rules" class="smpl">quoted-string</a> ) ]
    15451706</pre><p id="rfc.section.9.2.p.3">A server that does not understand or is unable to comply with any of the expectation values in the Expect field of a request <em class="bcp14">MUST</em> respond with appropriate error status. The server <em class="bcp14">MUST</em> respond with a 417 (Expectation Failed) status if any of the expectations cannot be met or, if there are other problems with
    1546          the request, some other 4xx status.
    1547       </p>
    1548       <p id="rfc.section.9.2.p.4">This header field is defined with extensible syntax to allow for future extensions. If a server receives a request containing
    1549          an Expect field that includes an expectation-extension that it does not support, it <em class="bcp14">MUST</em> respond with a 417 (Expectation Failed) status.
    1550       </p>
    1551       <p id="rfc.section.9.2.p.5">Comparison of expectation values is case-insensitive for unquoted tokens (including the 100-continue token), and is case-sensitive
    1552          for quoted-string expectation-extensions.
    1553       </p>
    1554       <p id="rfc.section.9.2.p.6">The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy <em class="bcp14">MUST</em> return a 417 (Expectation Failed) status if it receives a request with an expectation that it cannot meet. However, the Expect
    1555          request-header itself is end-to-end; it <em class="bcp14">MUST</em> be forwarded if the request is forwarded.
    1556       </p>
    1557       <p id="rfc.section.9.2.p.7">Many older HTTP/1.0 and HTTP/1.1 applications do not understand the Expect header.</p>
    1558       <p id="rfc.section.9.2.p.8">See <a href="p1-messaging.html#use.of.the.100.status" title="Use of the 100 (Continue) Status">Section 7.2.3</a> of <a href="#Part1" id="rfc.xref.Part1.28"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a> for the use of the 100 (Continue) status.
    1559       </p>
    1560       <div id="rfc.iref.f.1"></div>
    1561       <div id="rfc.iref.h.4"></div>
    1562       <h2 id="rfc.section.9.3"><a href="#rfc.section.9.3">9.3</a>&nbsp;<a id="header.from" href="#header.from">From</a></h2>
    1563       <p id="rfc.section.9.3.p.1">The "From" request-header field, if given, <em class="bcp14">SHOULD</em> contain an Internet e-mail address for the human user who controls the requesting user agent. The address <em class="bcp14">SHOULD</em> be machine-usable, as defined by "mailbox" in <a href="http://tools.ietf.org/html/rfc5322#section-3.4">Section 3.4</a> of <a href="#RFC5322" id="rfc.xref.RFC5322.1"><cite title="Internet Message Format">[RFC5322]</cite></a>:
    1564       </p>
    1565       <div id="rfc.figure.u.15"></div><pre class="inline"><span id="rfc.iref.g.16"></span><span id="rfc.iref.g.17"></span>  <a href="#header.from" class="smpl">From</a>    = "From" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.from" class="smpl">From-v</a>
     1707               the request, some other 4xx status.
     1708            </p>
     1709            <p id="rfc.section.9.2.p.4">This header field is defined with extensible syntax to allow for future extensions. If a server receives a request containing
     1710               an Expect field that includes an expectation-extension that it does not support, it <em class="bcp14">MUST</em> respond with a 417 (Expectation Failed) status.
     1711            </p>
     1712            <p id="rfc.section.9.2.p.5">Comparison of expectation values is case-insensitive for unquoted tokens (including the 100-continue token), and is case-sensitive
     1713               for quoted-string expectation-extensions.
     1714            </p>
     1715            <p id="rfc.section.9.2.p.6">The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy <em class="bcp14">MUST</em> return a 417 (Expectation Failed) status if it receives a request with an expectation that it cannot meet. However, the Expect
     1716               request-header itself is end-to-end; it <em class="bcp14">MUST</em> be forwarded if the request is forwarded.
     1717            </p>
     1718            <p id="rfc.section.9.2.p.7">Many older HTTP/1.0 and HTTP/1.1 applications do not understand the Expect header.</p>
     1719            <p id="rfc.section.9.2.p.8">See <a href="p1-messaging.html#use.of.the.100.status" title="Use of the 100 (Continue) Status">Section 7.2.3</a> of <a href="#Part1" id="rfc.xref.Part1.28"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a> for the use of the 100 (Continue) status.
     1720            </p>
     1721         </div>
     1722         <div id="header.from">
     1723            <div id="rfc.iref.f.1"></div>
     1724            <div id="rfc.iref.h.4"></div>
     1725            <h2 id="rfc.section.9.3"><a href="#rfc.section.9.3">9.3</a>&nbsp;<a href="#header.from">From</a></h2>
     1726            <p id="rfc.section.9.3.p.1">The "From" request-header field, if given, <em class="bcp14">SHOULD</em> contain an Internet e-mail address for the human user who controls the requesting user agent. The address <em class="bcp14">SHOULD</em> be machine-usable, as defined by "mailbox" in <a href="https://tools.ietf.org/html/rfc5322#section-3.4">Section 3.4</a> of <a href="#RFC5322" id="rfc.xref.RFC5322.1"><cite title="Internet Message Format">[RFC5322]</cite></a>:
     1727            </p>
     1728            <div id="rfc.figure.u.15"></div><pre class="inline"><span id="rfc.iref.g.16"></span><span id="rfc.iref.g.17"></span>  <a href="#header.from" class="smpl">From</a>    = "From" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.from" class="smpl">From-v</a>
    15661729  <a href="#header.from" class="smpl">From-v</a>  = <a href="#header.from" class="smpl">mailbox</a>
    15671730 
    1568   <a href="#header.from" class="smpl">mailbox</a> = &lt;mailbox, defined in <a href="#RFC5322" id="rfc.xref.RFC5322.2"><cite title="Internet Message Format">[RFC5322]</cite></a>, <a href="http://tools.ietf.org/html/rfc5322#section-3.4">Section 3.4</a>&gt;
     1731  <a href="#header.from" class="smpl">mailbox</a> = &lt;mailbox, defined in <a href="#RFC5322" id="rfc.xref.RFC5322.2"><cite title="Internet Message Format">[RFC5322]</cite></a>, <a href="https://tools.ietf.org/html/rfc5322#section-3.4">Section 3.4</a>&gt;
    15691732</pre><p id="rfc.section.9.3.p.3">An example is:</p>
    1570       <div id="rfc.figure.u.16"></div><pre class="text">  From: webmaster@example.org
     1733            <div id="rfc.figure.u.16"></div><pre class="text">  From: webmaster@example.org
    15711734</pre><p id="rfc.section.9.3.p.5">This header field <em class="bcp14">MAY</em> be used for logging purposes and as a means for identifying the source of invalid or unwanted requests. It <em class="bcp14">SHOULD NOT</em> be used as an insecure form of access protection. The interpretation of this field is that the request is being performed
    1572          on behalf of the person given, who accepts responsibility for the method performed. In particular, robot agents <em class="bcp14">SHOULD</em> include this header so that the person responsible for running the robot can be contacted if problems occur on the receiving
    1573          end.
    1574       </p>
    1575       <p id="rfc.section.9.3.p.6">The Internet e-mail address in this field <em class="bcp14">MAY</em> be separate from the Internet host which issued the request. For example, when a request is passed through a proxy the original
    1576          issuer's address <em class="bcp14">SHOULD</em> be used.
    1577       </p>
    1578       <p id="rfc.section.9.3.p.7">The client <em class="bcp14">SHOULD NOT</em> send the From header field without the user's approval, as it might conflict with the user's privacy interests or their site's
    1579          security policy. It is strongly recommended that the user be able to disable, enable, and modify the value of this field at
    1580          any time prior to a request.
    1581       </p>
    1582       <div id="rfc.iref.l.1"></div>
    1583       <div id="rfc.iref.h.5"></div>
    1584       <h2 id="rfc.section.9.4"><a href="#rfc.section.9.4">9.4</a>&nbsp;<a id="header.location" href="#header.location">Location</a></h2>
    1585       <p id="rfc.section.9.4.p.1">The "Location" response-header field is used to identify a newly created resource, or to redirect the recipient to a different
    1586          location for completion of the request.
    1587       </p>
    1588       <p id="rfc.section.9.4.p.2">For 201 (Created) responses, the Location is the URI of the new resource which was created by the request. For 3xx responses,
    1589          the location <em class="bcp14">SHOULD</em> indicate the server's preferred URI for automatic redirection to the resource.
    1590       </p>
    1591       <p id="rfc.section.9.4.p.3">The field value consists of a single URI-reference. When it has the form of a relative reference (<a href="#RFC3986" id="rfc.xref.RFC3986.1"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="http://tools.ietf.org/html/rfc3986#section-4.2">Section 4.2</a>), the final value is computed by resolving it against the effective request URI (<a href="#RFC3986" id="rfc.xref.RFC3986.2"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="http://tools.ietf.org/html/rfc3986#section-5">Section 5</a>).
    1592       </p>
    1593       <div id="rfc.figure.u.17"></div><pre class="inline"><span id="rfc.iref.g.18"></span><span id="rfc.iref.g.19"></span>  <a href="#header.location" class="smpl">Location</a>       = "Location" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.location" class="smpl">Location-v</a>
     1735               on behalf of the person given, who accepts responsibility for the method performed. In particular, robot agents <em class="bcp14">SHOULD</em> include this header so that the person responsible for running the robot can be contacted if problems occur on the receiving
     1736               end.
     1737            </p>
     1738            <p id="rfc.section.9.3.p.6">The Internet e-mail address in this field <em class="bcp14">MAY</em> be separate from the Internet host which issued the request. For example, when a request is passed through a proxy the original
     1739               issuer's address <em class="bcp14">SHOULD</em> be used.
     1740            </p>
     1741            <p id="rfc.section.9.3.p.7">The client <em class="bcp14">SHOULD NOT</em> send the From header field without the user's approval, as it might conflict with the user's privacy interests or their site's
     1742               security policy. It is strongly recommended that the user be able to disable, enable, and modify the value of this field at
     1743               any time prior to a request.
     1744            </p>
     1745         </div>
     1746         <div id="header.location">
     1747            <div id="rfc.iref.l.1"></div>
     1748            <div id="rfc.iref.h.5"></div>
     1749            <h2 id="rfc.section.9.4"><a href="#rfc.section.9.4">9.4</a>&nbsp;<a href="#header.location">Location</a></h2>
     1750            <p id="rfc.section.9.4.p.1">The "Location" response-header field is used to identify a newly created resource, or to redirect the recipient to a different
     1751               location for completion of the request.
     1752            </p>
     1753            <p id="rfc.section.9.4.p.2">For 201 (Created) responses, the Location is the URI of the new resource which was created by the request. For 3xx responses,
     1754               the location <em class="bcp14">SHOULD</em> indicate the server's preferred URI for automatic redirection to the resource.
     1755            </p>
     1756            <p id="rfc.section.9.4.p.3">The field value consists of a single URI-reference. When it has the form of a relative reference (<a href="#RFC3986" id="rfc.xref.RFC3986.1"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="https://tools.ietf.org/html/rfc3986#section-4.2">Section 4.2</a>), the final value is computed by resolving it against the effective request URI (<a href="#RFC3986" id="rfc.xref.RFC3986.2"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="https://tools.ietf.org/html/rfc3986#section-5">Section 5</a>).
     1757            </p>
     1758            <div id="rfc.figure.u.17"></div><pre class="inline"><span id="rfc.iref.g.18"></span><span id="rfc.iref.g.19"></span>  <a href="#header.location" class="smpl">Location</a>       = "Location" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.location" class="smpl">Location-v</a>
    15941759  <a href="#header.location" class="smpl">Location-v</a>     = <a href="#abnf.dependencies" class="smpl">URI-reference</a>
    1595 </pre><div id="rfc.figure.u.18"></div> 
    1596       <p>Examples are:</p>  <pre class="text">  Location: http://www.example.org/pub/WWW/People.html#tim
     1760</pre><div id="rfc.figure.u.18"></div>
     1761            <p>Examples are:</p><pre class="text">  Location: http://www.example.org/pub/WWW/People.html#tim
    15971762</pre><div id="rfc.figure.u.19"></div><pre class="text">  Location: /index.html
    15981763</pre><p id="rfc.section.9.4.p.7">There are circumstances in which a fragment identifier in a Location URI would not be appropriate: </p>
    1599       <ul>
    1600          <li>With a 201 Created response, because in this usage the Location header specifies the URI for the entire created resource.</li>
    1601          <li>With 305 Use Proxy.</li>
    1602       </ul>
    1603       <div class="note" id="rfc.section.9.4.p.8">
    1604          <p> <b>Note:</b> This specification does not define precedence rules for the case where the original URI, as navigated to by the user agent,
    1605             and the Location header field value both contain fragment identifiers.
    1606          </p>
    1607       </div>
    1608       <div class="note" id="rfc.section.9.4.p.9">
    1609          <p> <b>Note:</b> The Content-Location header field (<a href="p3-payload.html#header.content-location" title="Content-Location">Section 5.7</a> of <a href="#Part3" id="rfc.xref.Part3.11"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>) differs from Location in that the Content-Location identifies the original location of the entity enclosed in the response.
    1610             It is therefore possible for a response to contain header fields for both Location and Content-Location.
    1611          </p>
    1612       </div>
    1613       <div id="rfc.iref.m.9"></div>
    1614       <div id="rfc.iref.h.6"></div>
    1615       <h2 id="rfc.section.9.5"><a href="#rfc.section.9.5">9.5</a>&nbsp;<a id="header.max-forwards" href="#header.max-forwards">Max-Forwards</a></h2>
    1616       <p id="rfc.section.9.5.p.1">The "Max-Forwards" request-header field provides a mechanism with the TRACE (<a href="#TRACE" id="rfc.xref.TRACE.2" title="TRACE">Section&nbsp;7.8</a>) and OPTIONS (<a href="#OPTIONS" id="rfc.xref.OPTIONS.2" title="OPTIONS">Section&nbsp;7.2</a>) methods to limit the number of times that the request is forwarded by proxies or gateways. This can be useful when the client
    1617          is attempting to trace a request which appears to be failing or looping in mid-chain.
    1618       </p>
    1619       <div id="rfc.figure.u.20"></div><pre class="inline"><span id="rfc.iref.g.20"></span><span id="rfc.iref.g.21"></span>  <a href="#header.max-forwards" class="smpl">Max-Forwards</a>   = "Max-Forwards" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.max-forwards" class="smpl">Max-Forwards-v</a>
     1764            <ul>
     1765               <li>With a 201 Created response, because in this usage the Location header specifies the URI for the entire created resource.</li>
     1766               <li>With 305 Use Proxy.</li>
     1767            </ul>
     1768            <div class="note" id="rfc.section.9.4.p.8">
     1769               <p><b>Note:</b> This specification does not define precedence rules for the case where the original URI, as navigated to by the user agent,
     1770                  and the Location header field value both contain fragment identifiers.
     1771               </p>
     1772            </div>
     1773            <div class="note" id="rfc.section.9.4.p.9">
     1774               <p><b>Note:</b> The Content-Location header field (<a href="p3-payload.html#header.content-location" title="Content-Location">Section 5.7</a> of <a href="#Part3" id="rfc.xref.Part3.11"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a>) differs from Location in that the Content-Location identifies the original location of the entity enclosed in the response.
     1775                  It is therefore possible for a response to contain header fields for both Location and Content-Location.
     1776               </p>
     1777            </div>
     1778         </div>
     1779         <div id="header.max-forwards">
     1780            <div id="rfc.iref.m.9"></div>
     1781            <div id="rfc.iref.h.6"></div>
     1782            <h2 id="rfc.section.9.5"><a href="#rfc.section.9.5">9.5</a>&nbsp;<a href="#header.max-forwards">Max-Forwards</a></h2>
     1783            <p id="rfc.section.9.5.p.1">The "Max-Forwards" request-header field provides a mechanism with the TRACE (<a href="#TRACE" id="rfc.xref.TRACE.2" title="TRACE">Section&nbsp;7.8</a>) and OPTIONS (<a href="#OPTIONS" id="rfc.xref.OPTIONS.2" title="OPTIONS">Section&nbsp;7.2</a>) methods to limit the number of times that the request is forwarded by proxies or gateways. This can be useful when the client
     1784               is attempting to trace a request which appears to be failing or looping in mid-chain.
     1785            </p>
     1786            <div id="rfc.figure.u.20"></div><pre class="inline"><span id="rfc.iref.g.20"></span><span id="rfc.iref.g.21"></span>  <a href="#header.max-forwards" class="smpl">Max-Forwards</a>   = "Max-Forwards" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.max-forwards" class="smpl">Max-Forwards-v</a>
    16201787  <a href="#header.max-forwards" class="smpl">Max-Forwards-v</a> = 1*<a href="#notation" class="smpl">DIGIT</a>
    16211788</pre><p id="rfc.section.9.5.p.3">The Max-Forwards value is a decimal integer indicating the remaining number of times this request message may be forwarded.</p>
    1622       <p id="rfc.section.9.5.p.4">Each proxy or gateway recipient of a TRACE or OPTIONS request containing a Max-Forwards header field <em class="bcp14">MUST</em> check and update its value prior to forwarding the request. If the received value is zero (0), the recipient <em class="bcp14">MUST NOT</em> forward the request; instead, it <em class="bcp14">MUST</em> respond as the final recipient. If the received Max-Forwards value is greater than zero, then the forwarded message <em class="bcp14">MUST</em> contain an updated Max-Forwards field with a value decremented by one (1).
    1623       </p>
    1624       <p id="rfc.section.9.5.p.5">The Max-Forwards header field <em class="bcp14">MAY</em> be ignored for all other methods defined by this specification and for any extension methods for which it is not explicitly
    1625          referred to as part of that method definition.
    1626       </p>
    1627       <div id="rfc.iref.r.1"></div>
    1628       <div id="rfc.iref.h.7"></div>
    1629       <h2 id="rfc.section.9.6"><a href="#rfc.section.9.6">9.6</a>&nbsp;<a id="header.referer" href="#header.referer">Referer</a></h2>
    1630       <p id="rfc.section.9.6.p.1">The "Referer" [sic] request-header field allows the client to specify the URI of the resource from which the Effective Request
    1631          URI was obtained (the "referrer", although the header field is misspelled.).
    1632       </p>
    1633       <p id="rfc.section.9.6.p.2">The Referer header allows servers to generate lists of back-links to resources for interest, logging, optimized caching, etc.
    1634          It also allows obsolete or mistyped links to be traced for maintenance. Some servers use Referer as a means of controlling
    1635          where they allow links from (so-called "deep linking"), but it should be noted that legitimate requests are not required to
    1636          contain a Referer header field.
    1637       </p>
    1638       <p id="rfc.section.9.6.p.3">If the Effective Request URI was obtained from a source that does not have its own URI (e.g., input from the user keyboard),
    1639          the Referer field <em class="bcp14">MUST</em> either be sent with the value "about:blank", or not be sent at all. Note that this requirement does not apply to sources with
    1640          non-HTTP URIs (e.g., FTP).
    1641       </p>
    1642       <div id="rfc.figure.u.21"></div><pre class="inline"><span id="rfc.iref.g.22"></span><span id="rfc.iref.g.23"></span>  <a href="#header.referer" class="smpl">Referer</a>        = "Referer" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.referer" class="smpl">Referer-v</a>
     1789            <p id="rfc.section.9.5.p.4">Each proxy or gateway recipient of a TRACE or OPTIONS request containing a Max-Forwards header field <em class="bcp14">MUST</em> check and update its value prior to forwarding the request. If the received value is zero (0), the recipient <em class="bcp14">MUST NOT</em> forward the request; instead, it <em class="bcp14">MUST</em> respond as the final recipient. If the received Max-Forwards value is greater than zero, then the forwarded message <em class="bcp14">MUST</em> contain an updated Max-Forwards field with a value decremented by one (1).
     1790            </p>
     1791            <p id="rfc.section.9.5.p.5">The Max-Forwards header field <em class="bcp14">MAY</em> be ignored for all other methods defined by this specification and for any extension methods for which it is not explicitly
     1792               referred to as part of that method definition.
     1793            </p>
     1794         </div>
     1795         <div id="header.referer">
     1796            <div id="rfc.iref.r.1"></div>
     1797            <div id="rfc.iref.h.7"></div>
     1798            <h2 id="rfc.section.9.6"><a href="#rfc.section.9.6">9.6</a>&nbsp;<a href="#header.referer">Referer</a></h2>
     1799            <p id="rfc.section.9.6.p.1">The "Referer" [sic] request-header field allows the client to specify the URI of the resource from which the Effective Request
     1800               URI was obtained (the "referrer", although the header field is misspelled.).
     1801            </p>
     1802            <p id="rfc.section.9.6.p.2">The Referer header allows servers to generate lists of back-links to resources for interest, logging, optimized caching, etc.
     1803               It also allows obsolete or mistyped links to be traced for maintenance. Some servers use Referer as a means of controlling
     1804               where they allow links from (so-called "deep linking"), but it should be noted that legitimate requests are not required to
     1805               contain a Referer header field.
     1806            </p>
     1807            <p id="rfc.section.9.6.p.3">If the Effective Request URI was obtained from a source that does not have its own URI (e.g., input from the user keyboard),
     1808               the Referer field <em class="bcp14">MUST</em> either be sent with the value "about:blank", or not be sent at all. Note that this requirement does not apply to sources with
     1809               non-HTTP URIs (e.g., FTP).
     1810            </p>
     1811            <div id="rfc.figure.u.21"></div><pre class="inline"><span id="rfc.iref.g.22"></span><span id="rfc.iref.g.23"></span>  <a href="#header.referer" class="smpl">Referer</a>        = "Referer" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.referer" class="smpl">Referer-v</a>
    16431812  <a href="#header.referer" class="smpl">Referer-v</a>      = <a href="#abnf.dependencies" class="smpl">absolute-URI</a> / <a href="#abnf.dependencies" class="smpl">partial-URI</a>
    16441813</pre><p id="rfc.section.9.6.p.5">Example:</p>
    1645       <div id="rfc.figure.u.22"></div><pre class="text">  Referer: http://www.example.org/hypertext/Overview.html
     1814            <div id="rfc.figure.u.22"></div><pre class="text">  Referer: http://www.example.org/hypertext/Overview.html
    16461815</pre><p id="rfc.section.9.6.p.7">If the field value is a relative URI, it <em class="bcp14">SHOULD</em> be interpreted relative to the Effective Request URI. The URI <em class="bcp14">MUST NOT</em> include a fragment. See <a href="#encoding.sensitive.information.in.uris" title="Encoding Sensitive Information in URIs">Section&nbsp;11.2</a> for security considerations.
    1647       </p>
    1648       <div id="rfc.iref.r.2"></div>
    1649       <div id="rfc.iref.h.8"></div>
    1650       <h2 id="rfc.section.9.7"><a href="#rfc.section.9.7">9.7</a>&nbsp;<a id="header.retry-after" href="#header.retry-after">Retry-After</a></h2>
    1651       <p id="rfc.section.9.7.p.1">The response-header "Retry-After" field can be used with a 503 (Service Unavailable) response to indicate how long the service
    1652          is expected to be unavailable to the requesting client. This field <em class="bcp14">MAY</em> also be used with any 3xx (Redirection) response to indicate the minimum time the user-agent is asked wait before issuing
    1653          the redirected request.
    1654       </p>
    1655       <p id="rfc.section.9.7.p.2">The value of this field can be either an HTTP-date or an integer number of seconds (in decimal) after the time of the response.</p>
    1656       <div id="rfc.figure.u.23"></div><pre class="inline"><span id="rfc.iref.g.24"></span><span id="rfc.iref.g.25"></span>  <a href="#header.retry-after" class="smpl">Retry-After</a>   = "Retry-After" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.retry-after" class="smpl">Retry-After-v</a>
     1816            </p>
     1817         </div>
     1818         <div id="header.retry-after">
     1819            <div id="rfc.iref.r.2"></div>
     1820            <div id="rfc.iref.h.8"></div>
     1821            <h2 id="rfc.section.9.7"><a href="#rfc.section.9.7">9.7</a>&nbsp;<a href="#header.retry-after">Retry-After</a></h2>
     1822            <p id="rfc.section.9.7.p.1">The response-header "Retry-After" field can be used with a 503 (Service Unavailable) response to indicate how long the service
     1823               is expected to be unavailable to the requesting client. This field <em class="bcp14">MAY</em> also be used with any 3xx (Redirection) response to indicate the minimum time the user-agent is asked wait before issuing
     1824               the redirected request.
     1825            </p>
     1826            <p id="rfc.section.9.7.p.2">The value of this field can be either an HTTP-date or an integer number of seconds (in decimal) after the time of the response.</p>
     1827            <div id="rfc.figure.u.23"></div><pre class="inline"><span id="rfc.iref.g.24"></span><span id="rfc.iref.g.25"></span>  <a href="#header.retry-after" class="smpl">Retry-After</a>   = "Retry-After" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.retry-after" class="smpl">Retry-After-v</a>
    16571828  <a href="#header.retry-after" class="smpl">Retry-After-v</a> = <a href="#abnf.dependencies" class="smpl">HTTP-date</a> / <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>
    16581829</pre><div id="rule.delta-seconds">
    1659          <p id="rfc.section.9.7.p.4"> Time spans are non-negative decimal integers, representing time in seconds.</p>
    1660       </div>
    1661       <div id="rfc.figure.u.24"></div><pre class="inline"><span id="rfc.iref.g.26"></span>  <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>  = 1*<a href="#notation" class="smpl">DIGIT</a>
     1830               <p id="rfc.section.9.7.p.4"> Time spans are non-negative decimal integers, representing time in seconds.</p>
     1831            </div>
     1832            <div id="rfc.figure.u.24"></div><pre class="inline"><span id="rfc.iref.g.26"></span>  <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>  = 1*<a href="#notation" class="smpl">DIGIT</a>
    16621833</pre><p id="rfc.section.9.7.p.6">Two examples of its use are</p>
    1663       <div id="rfc.figure.u.25"></div><pre class="text">  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
     1834            <div id="rfc.figure.u.25"></div><pre class="text">  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
    16641835  Retry-After: 120
    16651836</pre><p id="rfc.section.9.7.p.8">In the latter example, the delay is 2 minutes.</p>
    1666       <div id="rfc.iref.s.43"></div>
    1667       <div id="rfc.iref.h.9"></div>
    1668       <h2 id="rfc.section.9.8"><a href="#rfc.section.9.8">9.8</a>&nbsp;<a id="header.server" href="#header.server">Server</a></h2>
    1669       <p id="rfc.section.9.8.p.1">The "Server" response-header field contains information about the software used by the origin server to handle the request.</p>
    1670       <p id="rfc.section.9.8.p.2">The field can contain multiple product tokens (<a href="p1-messaging.html#product.tokens" title="Product Tokens">Section 6.3</a> of <a href="#Part1" id="rfc.xref.Part1.29"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) and comments (<a href="p1-messaging.html#header.fields" title="Header Fields">Section 3.2</a> of <a href="#Part1" id="rfc.xref.Part1.30"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) identifying the server and any significant subproducts. The product tokens are listed in order of their significance for
    1671          identifying the application.
    1672       </p>
    1673       <div id="rfc.figure.u.26"></div><pre class="inline"><span id="rfc.iref.g.27"></span><span id="rfc.iref.g.28"></span>  <a href="#header.server" class="smpl">Server</a>         = "Server" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.server" class="smpl">Server-v</a>
     1837         </div>
     1838         <div id="header.server">
     1839            <div id="rfc.iref.s.43"></div>
     1840            <div id="rfc.iref.h.9"></div>
     1841            <h2 id="rfc.section.9.8"><a href="#rfc.section.9.8">9.8</a>&nbsp;<a href="#header.server">Server</a></h2>
     1842            <p id="rfc.section.9.8.p.1">The "Server" response-header field contains information about the software used by the origin server to handle the request.</p>
     1843            <p id="rfc.section.9.8.p.2">The field can contain multiple product tokens (<a href="p1-messaging.html#product.tokens" title="Product Tokens">Section 6.3</a> of <a href="#Part1" id="rfc.xref.Part1.29"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) and comments (<a href="p1-messaging.html#header.fields" title="Header Fields">Section 3.2</a> of <a href="#Part1" id="rfc.xref.Part1.30"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) identifying the server and any significant subproducts. The product tokens are listed in order of their significance for
     1844               identifying the application.
     1845            </p>
     1846            <div id="rfc.figure.u.26"></div><pre class="inline"><span id="rfc.iref.g.27"></span><span id="rfc.iref.g.28"></span>  <a href="#header.server" class="smpl">Server</a>         = "Server" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.server" class="smpl">Server-v</a>
    16741847  <a href="#header.server" class="smpl">Server-v</a>       = <a href="#abnf.dependencies" class="smpl">product</a>
    16751848                   *( <a href="#core.rules" class="smpl">RWS</a> ( <a href="#abnf.dependencies" class="smpl">product</a> / <a href="#abnf.dependencies" class="smpl">comment</a> ) )
    16761849</pre><p id="rfc.section.9.8.p.4">Example:</p>
    1677       <div id="rfc.figure.u.27"></div><pre class="text">  Server: CERN/3.0 libwww/2.17
     1850            <div id="rfc.figure.u.27"></div><pre class="text">  Server: CERN/3.0 libwww/2.17
    16781851</pre><p id="rfc.section.9.8.p.6">If the response is being forwarded through a proxy, the proxy application <em class="bcp14">MUST NOT</em> modify the Server response-header. Instead, it <em class="bcp14">MUST</em> include a Via field (as described in <a href="p1-messaging.html#header.via" title="Via">Section 9.9</a> of <a href="#Part1" id="rfc.xref.Part1.31"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>).
    1679       </p>
    1680       <div class="note" id="rfc.section.9.8.p.7">
    1681          <p> <b>Note:</b> Revealing the specific software version of the server might allow the server machine to become more vulnerable to attacks
    1682             against software that is known to contain security holes. Server implementors are encouraged to make this field a configurable
    1683             option.
    1684          </p>
    1685       </div>
    1686       <div id="rfc.iref.u.1"></div>
    1687       <div id="rfc.iref.h.10"></div>
    1688       <h2 id="rfc.section.9.9"><a href="#rfc.section.9.9">9.9</a>&nbsp;<a id="header.user-agent" href="#header.user-agent">User-Agent</a></h2>
    1689       <p id="rfc.section.9.9.p.1">The "User-Agent" request-header field contains information about the user agent originating the request. This is for statistical
    1690          purposes, the tracing of protocol violations, and automated recognition of user agents for the sake of tailoring responses
    1691          to avoid particular user agent limitations.
    1692       </p>
    1693       <p id="rfc.section.9.9.p.2">User agents <em class="bcp14">SHOULD</em> include this field with requests. The field can contain multiple product tokens (<a href="p1-messaging.html#product.tokens" title="Product Tokens">Section 6.3</a> of <a href="#Part1" id="rfc.xref.Part1.32"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) and comments (<a href="p1-messaging.html#header.fields" title="Header Fields">Section 3.2</a> of <a href="#Part1" id="rfc.xref.Part1.33"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) identifying the agent and any subproducts which form a significant part of the user agent. By convention, the product tokens
    1694          are listed in order of their significance for identifying the application.
    1695       </p>
    1696       <div id="rfc.figure.u.28"></div><pre class="inline"><span id="rfc.iref.g.29"></span><span id="rfc.iref.g.30"></span>  <a href="#header.user-agent" class="smpl">User-Agent</a>     = "User-Agent" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.user-agent" class="smpl">User-Agent-v</a>
     1852            </p>
     1853            <div class="note" id="rfc.section.9.8.p.7">
     1854               <p><b>Note:</b> Revealing the specific software version of the server might allow the server machine to become more vulnerable to attacks
     1855                  against software that is known to contain security holes. Server implementors are encouraged to make this field a configurable
     1856                  option.
     1857               </p>
     1858            </div>
     1859         </div>
     1860         <div id="header.user-agent">
     1861            <div id="rfc.iref.u.1"></div>
     1862            <div id="rfc.iref.h.10"></div>
     1863            <h2 id="rfc.section.9.9"><a href="#rfc.section.9.9">9.9</a>&nbsp;<a href="#header.user-agent">User-Agent</a></h2>
     1864            <p id="rfc.section.9.9.p.1">The "User-Agent" request-header field contains information about the user agent originating the request. This is for statistical
     1865               purposes, the tracing of protocol violations, and automated recognition of user agents for the sake of tailoring responses
     1866               to avoid particular user agent limitations.
     1867            </p>
     1868            <p id="rfc.section.9.9.p.2">User agents <em class="bcp14">SHOULD</em> include this field with requests. The field can contain multiple product tokens (<a href="p1-messaging.html#product.tokens" title="Product Tokens">Section 6.3</a> of <a href="#Part1" id="rfc.xref.Part1.32"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) and comments (<a href="p1-messaging.html#header.fields" title="Header Fields">Section 3.2</a> of <a href="#Part1" id="rfc.xref.Part1.33"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) identifying the agent and any subproducts which form a significant part of the user agent. By convention, the product tokens
     1869               are listed in order of their significance for identifying the application.
     1870            </p>
     1871            <div id="rfc.figure.u.28"></div><pre class="inline"><span id="rfc.iref.g.29"></span><span id="rfc.iref.g.30"></span>  <a href="#header.user-agent" class="smpl">User-Agent</a>     = "User-Agent" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.user-agent" class="smpl">User-Agent-v</a>
    16971872  <a href="#header.user-agent" class="smpl">User-Agent-v</a>   = <a href="#abnf.dependencies" class="smpl">product</a>
    16981873                   *( <a href="#core.rules" class="smpl">RWS</a> ( <a href="#abnf.dependencies" class="smpl">product</a> / <a href="#abnf.dependencies" class="smpl">comment</a> ) )
    16991874</pre><p id="rfc.section.9.9.p.4">Example:</p>
    1700       <div id="rfc.figure.u.29"></div><pre class="text">  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
    1701 </pre><h1 id="rfc.section.10"><a href="#rfc.section.10">10.</a>&nbsp;<a id="IANA.considerations" href="#IANA.considerations">IANA Considerations</a></h1>
    1702       <h2 id="rfc.section.10.1"><a href="#rfc.section.10.1">10.1</a>&nbsp;<a id="method.registration" href="#method.registration">Method Registry</a></h2>
    1703       <p id="rfc.section.10.1.p.1">The registration procedure for HTTP Methods is defined by <a href="#method.registry" title="Method Registry">Section&nbsp;2.1</a> of this document.
    1704       </p>
    1705       <p id="rfc.section.10.1.p.2">The HTTP Method Registry should be created at &lt;<a href="http://www.iana.org/assignments/http-methods">http://www.iana.org/assignments/http-methods</a>&gt; and be populated with the registrations below:
    1706       </p>
    1707       <div id="rfc.table.1">
    1708          <div id="iana.method.registration.table"></div>
    1709          <table class="tt full left" cellpadding="3" cellspacing="0">
    1710             <thead>
    1711                <tr>
    1712                   <th>Method</th>
    1713                   <th>Safe</th>
    1714                   <th>Reference</th>
    1715                </tr>
    1716             </thead>
    1717             <tbody>
    1718                <tr>
    1719                   <td class="left">CONNECT</td>
    1720                   <td class="left">no</td>
    1721                   <td class="left"> <a href="#CONNECT" id="rfc.xref.CONNECT.2" title="CONNECT">Section&nbsp;7.9</a>
    1722                   </td>
    1723                </tr>
    1724                <tr>
    1725                   <td class="left">DELETE</td>
    1726                   <td class="left">no</td>
    1727                   <td class="left"> <a href="#DELETE" id="rfc.xref.DELETE.2" title="DELETE">Section&nbsp;7.7</a>
    1728                   </td>
    1729                </tr>
    1730                <tr>
    1731                   <td class="left">GET</td>
    1732                   <td class="left">yes</td>
    1733                   <td class="left"> <a href="#GET" id="rfc.xref.GET.2" title="GET">Section&nbsp;7.3</a>
    1734                   </td>
    1735                </tr>
    1736                <tr>
    1737                   <td class="left">HEAD</td>
    1738                   <td class="left">yes</td>
    1739                   <td class="left"> <a href="#HEAD" id="rfc.xref.HEAD.2" title="HEAD">Section&nbsp;7.4</a>
    1740                   </td>
    1741                </tr>
    1742                <tr>
    1743                   <td class="left">OPTIONS</td>
    1744                   <td class="left">yes</td>
    1745                   <td class="left"> <a href="#OPTIONS" id="rfc.xref.OPTIONS.3" title="OPTIONS">Section&nbsp;7.2</a>
    1746                   </td>
    1747                </tr>
    1748                <tr>
    1749                   <td class="left">POST</td>
    1750                   <td class="left">no</td>
    1751                   <td class="left"> <a href="#POST" id="rfc.xref.POST.2" title="POST">Section&nbsp;7.5</a>
    1752                   </td>
    1753                </tr>
    1754                <tr>
    1755                   <td class="left">PUT</td>
    1756                   <td class="left">no</td>
    1757                   <td class="left"> <a href="#PUT" id="rfc.xref.PUT.2" title="PUT">Section&nbsp;7.6</a>
    1758                   </td>
    1759                </tr>
    1760                <tr>
    1761                   <td class="left">TRACE</td>
    1762                   <td class="left">yes</td>
    1763                   <td class="left"> <a href="#TRACE" id="rfc.xref.TRACE.3" title="TRACE">Section&nbsp;7.8</a>
    1764                   </td>
    1765                </tr>
    1766             </tbody>
    1767          </table>
     1875            <div id="rfc.figure.u.29"></div><pre class="text">  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
     1876</pre></div>
    17681877      </div>
    1769       <h2 id="rfc.section.10.2"><a href="#rfc.section.10.2">10.2</a>&nbsp;<a id="status.code.registration" href="#status.code.registration">Status Code Registry</a></h2>
    1770       <p id="rfc.section.10.2.p.1">The registration procedure for HTTP Status Codes -- previously defined in <a href="http://tools.ietf.org/html/rfc2817#section-7.1">Section 7.1</a> of <a href="#RFC2817" id="rfc.xref.RFC2817.2"><cite title="Upgrading to TLS Within HTTP/1.1">[RFC2817]</cite></a> -- is now defined by <a href="#status.code.registry" title="Status Code Registry">Section&nbsp;4.1</a> of this document.
    1771       </p>
    1772       <p id="rfc.section.10.2.p.2">The HTTP Status Code Registry located at &lt;<a href="http://www.iana.org/assignments/http-status-codes">http://www.iana.org/assignments/http-status-codes</a>&gt; should be updated with the registrations below:
    1773       </p>
    1774       <div id="rfc.table.2">
    1775          <div id="iana.status.code.registration.table"></div>
    1776          <table class="tt full left" cellpadding="3" cellspacing="0">
    1777             <thead>
    1778                <tr>
    1779                   <th>Value</th>
    1780                   <th>Description</th>
    1781                   <th>Reference</th>
    1782                </tr>
    1783             </thead>
    1784             <tbody>
    1785                <tr>
    1786                   <td class="left">100</td>
    1787                   <td class="left">Continue</td>
    1788                   <td class="left"> <a href="#status.100" id="rfc.xref.status.100.2" title="100 Continue">Section&nbsp;8.1.1</a>
    1789                   </td>
    1790                </tr>
    1791                <tr>
    1792                   <td class="left">101</td>
    1793                   <td class="left">Switching Protocols</td>
    1794                   <td class="left"> <a href="#status.101" id="rfc.xref.status.101.2" title="101 Switching Protocols">Section&nbsp;8.1.2</a>
    1795                   </td>
    1796                </tr>
    1797                <tr>
    1798                   <td class="left">200</td>
    1799                   <td class="left">OK</td>
    1800                   <td class="left"> <a href="#status.200" id="rfc.xref.status.200.2" title="200 OK">Section&nbsp;8.2.1</a>
    1801                   </td>
    1802                </tr>
    1803                <tr>
    1804                   <td class="left">201</td>
    1805                   <td class="left">Created</td>
    1806                   <td class="left"> <a href="#status.201" id="rfc.xref.status.201.2" title="201 Created">Section&nbsp;8.2.2</a>
    1807                   </td>
    1808                </tr>
    1809                <tr>
    1810                   <td class="left">202</td>
    1811                   <td class="left">Accepted</td>
    1812                   <td class="left"> <a href="#status.202" id="rfc.xref.status.202.2" title="202 Accepted">Section&nbsp;8.2.3</a>
    1813                   </td>
    1814                </tr>
    1815                <tr>
    1816                   <td class="left">203</td>
    1817                   <td class="left">Non-Authoritative Information</td>
    1818                   <td class="left"> <a href="#status.203" id="rfc.xref.status.203.2" title="203 Non-Authoritative Information">Section&nbsp;8.2.4</a>
    1819                   </td>
    1820                </tr>
    1821                <tr>
    1822                   <td class="left">204</td>
    1823                   <td class="left">No Content</td>
    1824                   <td class="left"> <a href="#status.204" id="rfc.xref.status.204.2" title="204 No Content">Section&nbsp;8.2.5</a>
    1825                   </td>
    1826                </tr>
    1827                <tr>
    1828                   <td class="left">205</td>
    1829                   <td class="left">Reset Content</td>
    1830                   <td class="left"> <a href="#status.205" id="rfc.xref.status.205.2" title="205 Reset Content">Section&nbsp;8.2.6</a>
    1831                   </td>
    1832                </tr>
    1833                <tr>
    1834                   <td class="left">300</td>
    1835                   <td class="left">Multiple Choices</td>
    1836                   <td class="left"> <a href="#status.300" id="rfc.xref.status.300.2" title="300 Multiple Choices">Section&nbsp;8.3.1</a>
    1837                   </td>
    1838                </tr>
    1839                <tr>
    1840                   <td class="left">301</td>
    1841                   <td class="left">Moved Permanently</td>
    1842                   <td class="left"> <a href="#status.301" id="rfc.xref.status.301.2" title="301 Moved Permanently">Section&nbsp;8.3.2</a>
    1843                   </td>
    1844                </tr>
    1845                <tr>
    1846                   <td class="left">302</td>
    1847                   <td class="left">Found</td>
    1848                   <td class="left"> <a href="#status.302" id="rfc.xref.status.302.2" title="302 Found">Section&nbsp;8.3.3</a>
    1849                   </td>
    1850                </tr>
    1851                <tr>
    1852                   <td class="left">303</td>
    1853                   <td class="left">See Other</td>
    1854                   <td class="left"> <a href="#status.303" id="rfc.xref.status.303.3" title="303 See Other">Section&nbsp;8.3.4</a>
    1855                   </td>
    1856                </tr>
    1857                <tr>
    1858                   <td class="left">305</td>
    1859                   <td class="left">Use Proxy</td>
    1860                   <td class="left"> <a href="#status.305" id="rfc.xref.status.305.2" title="305 Use Proxy">Section&nbsp;8.3.6</a>
    1861                   </td>
    1862                </tr>
    1863                <tr>
    1864                   <td class="left">306</td>
    1865                   <td class="left">(Unused)</td>
    1866                   <td class="left"> <a href="#status.306" id="rfc.xref.status.306.1" title="306 (Unused)">Section&nbsp;8.3.7</a>
    1867                   </td>
    1868                </tr>
    1869                <tr>
    1870                   <td class="left">307</td>
    1871                   <td class="left">Temporary Redirect</td>
    1872                   <td class="left"> <a href="#status.307" id="rfc.xref.status.307.3" title="307 Temporary Redirect">Section&nbsp;8.3.8</a>
    1873                   </td>
    1874                </tr>
    1875                <tr>
    1876                   <td class="left">400</td>
    1877                   <td class="left">Bad Request</td>
    1878                   <td class="left"> <a href="#status.400" id="rfc.xref.status.400.2" title="400 Bad Request">Section&nbsp;8.4.1</a>
    1879                   </td>
    1880                </tr>
    1881                <tr>
    1882                   <td class="left">402</td>
    1883                   <td class="left">Payment Required</td>
    1884                   <td class="left"> <a href="#status.402" id="rfc.xref.status.402.2" title="402 Payment Required">Section&nbsp;8.4.3</a>
    1885                   </td>
    1886                </tr>
    1887                <tr>
    1888                   <td class="left">403</td>
    1889                   <td class="left">Forbidden</td>
    1890                   <td class="left"> <a href="#status.403" id="rfc.xref.status.403.2" title="403 Forbidden">Section&nbsp;8.4.4</a>
    1891                   </td>
    1892                </tr>
    1893                <tr>
    1894                   <td class="left">404</td>
    1895                   <td class="left">Not Found</td>
    1896                   <td class="left"> <a href="#status.404" id="rfc.xref.status.404.2" title="404 Not Found">Section&nbsp;8.4.5</a>
    1897                   </td>
    1898                </tr>
    1899                <tr>
    1900                   <td class="left">405</td>
    1901                   <td class="left">Method Not Allowed</td>
    1902                   <td class="left"> <a href="#status.405" id="rfc.xref.status.405.2" title="405 Method Not Allowed">Section&nbsp;8.4.6</a>
    1903                   </td>
    1904                </tr>
    1905                <tr>
    1906                   <td class="left">406</td>
    1907                   <td class="left">Not Acceptable</td>
    1908                   <td class="left"> <a href="#status.406" id="rfc.xref.status.406.2" title="406 Not Acceptable">Section&nbsp;8.4.7</a>
    1909                   </td>
    1910                </tr>
    1911                <tr>
    1912                   <td class="left">407</td>
    1913                   <td class="left">Proxy Authentication Required</td>
    1914                   <td class="left"> <a href="#status.407" id="rfc.xref.status.407.1" title="407 Proxy Authentication Required">Section&nbsp;8.4.8</a>
    1915                   </td>
    1916                </tr>
    1917                <tr>
    1918                   <td class="left">408</td>
    1919                   <td class="left">Request Timeout</td>
    1920                   <td class="left"> <a href="#status.408" id="rfc.xref.status.408.2" title="408 Request Timeout">Section&nbsp;8.4.9</a>
    1921                   </td>
    1922                </tr>
    1923                <tr>
    1924                   <td class="left">409</td>
    1925                   <td class="left">Conflict</td>
    1926                   <td class="left"> <a href="#status.409" id="rfc.xref.status.409.2" title="409 Conflict">Section&nbsp;8.4.10</a>
    1927                   </td>
    1928                </tr>
    1929                <tr>
    1930                   <td class="left">410</td>
    1931                   <td class="left">Gone</td>
    1932                   <td class="left"> <a href="#status.410" id="rfc.xref.status.410.2" title="410 Gone">Section&nbsp;8.4.11</a>
    1933                   </td>
    1934                </tr>
    1935                <tr>
    1936                   <td class="left">411</td>
    1937                   <td class="left">Length Required</td>
    1938                   <td class="left"> <a href="#status.411" id="rfc.xref.status.411.2" title="411 Length Required">Section&nbsp;8.4.12</a>
    1939                   </td>
    1940                </tr>
    1941                <tr>
    1942                   <td class="left">413</td>
    1943                   <td class="left">Request Entity Too Large</td>
    1944                   <td class="left"> <a href="#status.413" id="rfc.xref.status.413.2" title="413 Request Entity Too Large">Section&nbsp;8.4.14</a>
    1945                   </td>
    1946                </tr>
    1947                <tr>
    1948                   <td class="left">414</td>
    1949                   <td class="left">URI Too Long</td>
    1950                   <td class="left"> <a href="#status.414" id="rfc.xref.status.414.2" title="414 URI Too Long">Section&nbsp;8.4.15</a>
    1951                   </td>
    1952                </tr>
    1953                <tr>
    1954                   <td class="left">415</td>
    1955                   <td class="left">Unsupported Media Type</td>
    1956                   <td class="left"> <a href="#status.415" id="rfc.xref.status.415.2" title="415 Unsupported Media Type">Section&nbsp;8.4.16</a>
    1957                   </td>
    1958                </tr>
    1959                <tr>
    1960                   <td class="left">417</td>
    1961                   <td class="left">Expectation Failed</td>
    1962                   <td class="left"> <a href="#status.417" id="rfc.xref.status.417.2" title="417 Expectation Failed">Section&nbsp;8.4.18</a>
    1963                   </td>
    1964                </tr>
    1965                <tr>
    1966                   <td class="left">500</td>
    1967                   <td class="left">Internal Server Error</td>
    1968                   <td class="left"> <a href="#status.500" id="rfc.xref.status.500.2" title="500 Internal Server Error">Section&nbsp;8.5.1</a>
    1969                   </td>
    1970                </tr>
    1971                <tr>
    1972                   <td class="left">501</td>
    1973                   <td class="left">Not Implemented</td>
    1974                   <td class="left"> <a href="#status.501" id="rfc.xref.status.501.2" title="501 Not Implemented">Section&nbsp;8.5.2</a>
    1975                   </td>
    1976                </tr>
    1977                <tr>
    1978                   <td class="left">502</td>
    1979                   <td class="left">Bad Gateway</td>
    1980                   <td class="left"> <a href="#status.502" id="rfc.xref.status.502.2" title="502 Bad Gateway">Section&nbsp;8.5.3</a>
    1981                   </td>
    1982                </tr>
    1983                <tr>
    1984                   <td class="left">503</td>
    1985                   <td class="left">Service Unavailable</td>
    1986                   <td class="left"> <a href="#status.503" id="rfc.xref.status.503.2" title="503 Service Unavailable">Section&nbsp;8.5.4</a>
    1987                   </td>
    1988                </tr>
    1989                <tr>
    1990                   <td class="left">504</td>
    1991                   <td class="left">Gateway Timeout</td>
    1992                   <td class="left"> <a href="#status.504" id="rfc.xref.status.504.2" title="504 Gateway Timeout">Section&nbsp;8.5.5</a>
    1993                   </td>
    1994                </tr>
    1995                <tr>
    1996                   <td class="left">505</td>
    1997                   <td class="left">HTTP Version Not Supported</td>
    1998                   <td class="left"> <a href="#status.505" id="rfc.xref.status.505.2" title="505 HTTP Version Not Supported">Section&nbsp;8.5.6</a>
    1999                   </td>
    2000                </tr>
    2001             </tbody>
    2002          </table>
     1878      <div id="IANA.considerations">
     1879         <h1 id="rfc.section.10"><a href="#rfc.section.10">10.</a>&nbsp;<a href="#IANA.considerations">IANA Considerations</a></h1>
     1880         <div id="method.registration">
     1881            <h2 id="rfc.section.10.1"><a href="#rfc.section.10.1">10.1</a>&nbsp;<a href="#method.registration">Method Registry</a></h2>
     1882            <p id="rfc.section.10.1.p.1">The registration procedure for HTTP Methods is defined by <a href="#method.registry" title="Method Registry">Section&nbsp;2.1</a> of this document.
     1883            </p>
     1884            <p id="rfc.section.10.1.p.2">The HTTP Method Registry should be created at &lt;<a href="http://www.iana.org/assignments/http-methods">http://www.iana.org/assignments/http-methods</a>&gt; and be populated with the registrations below:
     1885            </p>
     1886            <div id="rfc.table.1">
     1887               <div id="iana.method.registration.table"></div>
     1888               <table class="tt full left" cellpadding="3" cellspacing="0">
     1889                  <thead>
     1890                     <tr>
     1891                        <th>Method</th>
     1892                        <th>Safe</th>
     1893                        <th>Reference</th>
     1894                     </tr>
     1895                  </thead>
     1896                  <tbody>
     1897                     <tr>
     1898                        <td class="left">CONNECT</td>
     1899                        <td class="left">no</td>
     1900                        <td class="left"><a href="#CONNECT" id="rfc.xref.CONNECT.2" title="CONNECT">Section&nbsp;7.9</a>
     1901                        </td>
     1902                     </tr>
     1903                     <tr>
     1904                        <td class="left">DELETE</td>
     1905                        <td class="left">no</td>
     1906                        <td class="left"><a href="#DELETE" id="rfc.xref.DELETE.2" title="DELETE">Section&nbsp;7.7</a>
     1907                        </td>
     1908                     </tr>
     1909                     <tr>
     1910                        <td class="left">GET</td>
     1911                        <td class="left">yes</td>
     1912                        <td class="left"><a href="#GET" id="rfc.xref.GET.2" title="GET">Section&nbsp;7.3</a>
     1913                        </td>
     1914                     </tr>
     1915                     <tr>
     1916                        <td class="left">HEAD</td>
     1917                        <td class="left">yes</td>
     1918                        <td class="left"><a href="#HEAD" id="rfc.xref.HEAD.2" title="HEAD">Section&nbsp;7.4</a>
     1919                        </td>
     1920                     </tr>
     1921                     <tr>
     1922                        <td class="left">OPTIONS</td>
     1923                        <td class="left">yes</td>
     1924                        <td class="left"><a href="#OPTIONS" id="rfc.xref.OPTIONS.3" title="OPTIONS">Section&nbsp;7.2</a>
     1925                        </td>
     1926                     </tr>
     1927                     <tr>
     1928                        <td class="left">POST</td>
     1929                        <td class="left">no</td>
     1930                        <td class="left"><a href="#POST" id="rfc.xref.POST.2" title="POST">Section&nbsp;7.5</a>
     1931                        </td>
     1932                     </tr>
     1933                     <tr>
     1934                        <td class="left">PUT</td>
     1935                        <td class="left">no</td>
     1936                        <td class="left"><a href="#PUT" id="rfc.xref.PUT.2" title="PUT">Section&nbsp;7.6</a>
     1937                        </td>
     1938                     </tr>
     1939                     <tr>
     1940                        <td class="left">TRACE</td>
     1941                        <td class="left">yes</td>
     1942                        <td class="left"><a href="#TRACE" id="rfc.xref.TRACE.3" title="TRACE">Section&nbsp;7.8</a>
     1943                        </td>
     1944                     </tr>
     1945                  </tbody>
     1946               </table>
     1947            </div>
     1948         </div>
     1949         <div id="status.code.registration">
     1950            <h2 id="rfc.section.10.2"><a href="#rfc.section.10.2">10.2</a>&nbsp;<a href="#status.code.registration">Status Code Registry</a></h2>
     1951            <p id="rfc.section.10.2.p.1">The registration procedure for HTTP Status Codes -- previously defined in <a href="https://tools.ietf.org/html/rfc2817#section-7.1">Section 7.1</a> of <a href="#RFC2817" id="rfc.xref.RFC2817.2"><cite title="Upgrading to TLS Within HTTP/1.1">[RFC2817]</cite></a> -- is now defined by <a href="#status.code.registry" title="Status Code Registry">Section&nbsp;4.1</a> of this document.
     1952            </p>
     1953            <p id="rfc.section.10.2.p.2">The HTTP Status Code Registry located at &lt;<a href="http://www.iana.org/assignments/http-status-codes">http://www.iana.org/assignments/http-status-codes</a>&gt; should be updated with the registrations below:
     1954            </p>
     1955            <div id="rfc.table.2">
     1956               <div id="iana.status.code.registration.table"></div>
     1957               <table class="tt full left" cellpadding="3" cellspacing="0">
     1958                  <thead>
     1959                     <tr>
     1960                        <th>Value</th>
     1961                        <th>Description</th>
     1962                        <th>Reference</th>
     1963                     </tr>
     1964                  </thead>
     1965                  <tbody>
     1966                     <tr>
     1967                        <td class="left">100</td>
     1968                        <td class="left">Continue</td>
     1969                        <td class="left"><a href="#status.100" id="rfc.xref.status.100.2" title="100 Continue">Section&nbsp;8.1.1</a>
     1970                        </td>
     1971                     </tr>
     1972                     <tr>
     1973                        <td class="left">101</td>
     1974                        <td class="left">Switching Protocols</td>
     1975                        <td class="left"><a href="#status.101" id="rfc.xref.status.101.2" title="101 Switching Protocols">Section&nbsp;8.1.2</a>
     1976                        </td>
     1977                     </tr>
     1978                     <tr>
     1979                        <td class="left">200</td>
     1980                        <td class="left">OK</td>
     1981                        <td class="left"><a href="#status.200" id="rfc.xref.status.200.2" title="200 OK">Section&nbsp;8.2.1</a>
     1982                        </td>
     1983                     </tr>
     1984                     <tr>
     1985                        <td class="left">201</td>
     1986                        <td class="left">Created</td>
     1987                        <td class="left"><a href="#status.201" id="rfc.xref.status.201.2" title="201 Created">Section&nbsp;8.2.2</a>
     1988                        </td>
     1989                     </tr>
     1990                     <tr>
     1991                        <td class="left">202</td>
     1992                        <td class="left">Accepted</td>
     1993                        <td class="left"><a href="#status.202" id="rfc.xref.status.202.2" title="202 Accepted">Section&nbsp;8.2.3</a>
     1994                        </td>
     1995                     </tr>
     1996                     <tr>
     1997                        <td class="left">203</td>
     1998                        <td class="left">Non-Authoritative Information</td>
     1999                        <td class="left"><a href="#status.203" id="rfc.xref.status.203.2" title="203 Non-Authoritative Information">Section&nbsp;8.2.4</a>
     2000                        </td>
     2001                     </tr>
     2002                     <tr>
     2003                        <td class="left">204</td>
     2004                        <td class="left">No Content</td>
     2005                        <td class="left"><a href="#status.204" id="rfc.xref.status.204.2" title="204 No Content">Section&nbsp;8.2.5</a>
     2006                        </td>
     2007                     </tr>
     2008                     <tr>
     2009                        <td class="left">205</td>
     2010                        <td class="left">Reset Content</td>
     2011                        <td class="left"><a href="#status.205" id="rfc.xref.status.205.2" title="205 Reset Content">Section&nbsp;8.2.6</a>
     2012                        </td>
     2013                     </tr>
     2014                     <tr>
     2015                        <td class="left">300</td>
     2016                        <td class="left">Multiple Choices</td>
     2017                        <td class="left"><a href="#status.300" id="rfc.xref.status.300.2" title="300 Multiple Choices">Section&nbsp;8.3.1</a>
     2018                        </td>
     2019                     </tr>
     2020                     <tr>
     2021                        <td class="left">301</td>
     2022                        <td class="left">Moved Permanently</td>
     2023                        <td class="left"><a href="#status.301" id="rfc.xref.status.301.2" title="301 Moved Permanently">Section&nbsp;8.3.2</a>
     2024                        </td>
     2025                     </tr>
     2026                     <tr>
     2027                        <td class="left">302</td>
     2028                        <td class="left">Found</td>
     2029                        <td class="left"><a href="#status.302" id="rfc.xref.status.302.2" title="302 Found">Section&nbsp;8.3.3</a>
     2030                        </td>
     2031                     </tr>
     2032                     <tr>
     2033                        <td class="left">303</td>
     2034                        <td class="left">See Other</td>
     2035                        <td class="left"><a href="#status.303" id="rfc.xref.status.303.3" title="303 See Other">Section&nbsp;8.3.4</a>
     2036                        </td>
     2037                     </tr>
     2038                     <tr>
     2039                        <td class="left">305</td>
     2040                        <td class="left">Use Proxy</td>
     2041                        <td class="left"><a href="#status.305" id="rfc.xref.status.305.2" title="305 Use Proxy">Section&nbsp;8.3.6</a>
     2042                        </td>
     2043                     </tr>
     2044                     <tr>
     2045                        <td class="left">306</td>
     2046                        <td class="left">(Unused)</td>
     2047                        <td class="left"><a href="#status.306" id="rfc.xref.status.306.1" title="306 (Unused)">Section&nbsp;8.3.7</a>
     2048                        </td>
     2049                     </tr>
     2050                     <tr>
     2051                        <td class="left">307</td>
     2052                        <td class="left">Temporary Redirect</td>
     2053                        <td class="left"><a href="#status.307" id="rfc.xref.status.307.3" title="307 Temporary Redirect">Section&nbsp;8.3.8</a>
     2054                        </td>
     2055                     </tr>
     2056                     <tr>
     2057                        <td class="left">400</td>
     2058                        <td class="left">Bad Request</td>
     2059                        <td class="left"><a href="#status.400" id="rfc.xref.status.400.2" title="400 Bad Request">Section&nbsp;8.4.1</a>
     2060                        </td>
     2061                     </tr>
     2062                     <tr>
     2063                        <td class="left">402</td>
     2064                        <td class="left">Payment Required</td>
     2065                        <td class="left"><a href="#status.402" id="rfc.xref.status.402.2" title="402 Payment Required">Section&nbsp;8.4.3</a>
     2066                        </td>
     2067                     </tr>
     2068                     <tr>
     2069                        <td class="left">403</td>
     2070                        <td class="left">Forbidden</td>
     2071                        <td class="left"><a href="#status.403" id="rfc.xref.status.403.2" title="403 Forbidden">Section&nbsp;8.4.4</a>
     2072                        </td>
     2073                     </tr>
     2074                     <tr>
     2075                        <td class="left">404</td>
     2076                        <td class="left">Not Found</td>
     2077                        <td class="left"><a href="#status.404" id="rfc.xref.status.404.2" title="404 Not Found">Section&nbsp;8.4.5</a>
     2078                        </td>
     2079                     </tr>
     2080                     <tr>
     2081                        <td class="left">405</td>
     2082                        <td class="left">Method Not Allowed</td>
     2083                        <td class="left"><a href="#status.405" id="rfc.xref.status.405.2" title="405 Method Not Allowed">Section&nbsp;8.4.6</a>
     2084                        </td>
     2085                     </tr>
     2086                     <tr>
     2087                        <td class="left">406</td>
     2088                        <td class="left">Not Acceptable</td>
     2089                        <td class="left"><a href="#status.406" id="rfc.xref.status.406.2" title="406 Not Acceptable">Section&nbsp;8.4.7</a>
     2090                        </td>
     2091                     </tr>
     2092                     <tr>
     2093                        <td class="left">407</td>
     2094                        <td class="left">Proxy Authentication Required</td>
     2095                        <td class="left"><a href="#status.407" id="rfc.xref.status.407.1" title="407 Proxy Authentication Required">Section&nbsp;8.4.8</a>
     2096                        </td>
     2097                     </tr>
     2098                     <tr>
     2099                        <td class="left">408</td>
     2100                        <td class="left">Request Timeout</td>
     2101                        <td class="left"><a href="#status.408" id="rfc.xref.status.408.2" title="408 Request Timeout">Section&nbsp;8.4.9</a>
     2102                        </td>
     2103                     </tr>
     2104                     <tr>
     2105                        <td class="left">409</td>
     2106                        <td class="left">Conflict</td>
     2107                        <td class="left"><a href="#status.409" id="rfc.xref.status.409.2" title="409 Conflict">Section&nbsp;8.4.10</a>
     2108                        </td>
     2109                     </tr>
     2110                     <tr>
     2111                        <td class="left">410</td>
     2112                        <td class="left">Gone</td>
     2113                        <td class="left"><a href="#status.410" id="rfc.xref.status.410.2" title="410 Gone">Section&nbsp;8.4.11</a>
     2114                        </td>
     2115                     </tr>
     2116                     <tr>
     2117                        <td class="left">411</td>
     2118                        <td class="left">Length Required</td>
     2119                        <td class="left"><a href="#status.411" id="rfc.xref.status.411.2" title="411 Length Required">Section&nbsp;8.4.12</a>
     2120                        </td>
     2121                     </tr>
     2122                     <tr>
     2123                        <td class="left">413</td>
     2124                        <td class="left">Request Entity Too Large</td>
     2125                        <td class="left"><a href="#status.413" id="rfc.xref.status.413.2" title="413 Request Entity Too Large">Section&nbsp;8.4.14</a>
     2126                        </td>
     2127                     </tr>
     2128                     <tr>
     2129                        <td class="left">414</td>
     2130                        <td class="left">URI Too Long</td>
     2131                        <td class="left"><a href="#status.414" id="rfc.xref.status.414.2" title="414 URI Too Long">Section&nbsp;8.4.15</a>
     2132                        </td>
     2133                     </tr>
     2134                     <tr>
     2135                        <td class="left">415</td>
     2136                        <td class="left">Unsupported Media Type</td>
     2137                        <td class="left"><a href="#status.415" id="rfc.xref.status.415.2" title="415 Unsupported Media Type">Section&nbsp;8.4.16</a>
     2138                        </td>
     2139                     </tr>
     2140                     <tr>
     2141                        <td class="left">417</td>
     2142                        <td class="left">Expectation Failed</td>
     2143                        <td class="left"><a href="#status.417" id="rfc.xref.status.417.2" title="417 Expectation Failed">Section&nbsp;8.4.18</a>
     2144                        </td>
     2145                     </tr>
     2146                     <tr>
     2147                        <td class="left">500</td>
     2148                        <td class="left">Internal Server Error</td>
     2149                        <td class="left"><a href="#status.500" id="rfc.xref.status.500.2" title="500 Internal Server Error">Section&nbsp;8.5.1</a>
     2150                        </td>
     2151                     </tr>
     2152                     <tr>
     2153                        <td class="left">501</td>
     2154                        <td class="left">Not Implemented</td>
     2155                        <td class="left"><a href="#status.501" id="rfc.xref.status.501.2" title="501 Not Implemented">Section&nbsp;8.5.2</a>
     2156                        </td>
     2157                     </tr>
     2158                     <tr>
     2159                        <td class="left">502</td>
     2160                        <td class="left">Bad Gateway</td>
     2161                        <td class="left"><a href="#status.502" id="rfc.xref.status.502.2" title="502 Bad Gateway">Section&nbsp;8.5.3</a>
     2162                        </td>
     2163                     </tr>
     2164                     <tr>
     2165                        <td class="left">503</td>
     2166                        <td class="left">Service Unavailable</td>
     2167                        <td class="left"><a href="#status.503" id="rfc.xref.status.503.2" title="503 Service Unavailable">Section&nbsp;8.5.4</a>
     2168                        </td>
     2169                     </tr>
     2170                     <tr>
     2171                        <td class="left">504</td>
     2172                        <td class="left">Gateway Timeout</td>
     2173                        <td class="left"><a href="#status.504" id="rfc.xref.status.504.2" title="504 Gateway Timeout">Section&nbsp;8.5.5</a>
     2174                        </td>
     2175                     </tr>
     2176                     <tr>
     2177                        <td class="left">505</td>
     2178                        <td class="left">HTTP Version Not Supported</td>
     2179                        <td class="left"><a href="#status.505" id="rfc.xref.status.505.2" title="505 HTTP Version Not Supported">Section&nbsp;8.5.6</a>
     2180                        </td>
     2181                     </tr>
     2182                  </tbody>
     2183               </table>
     2184            </div>
     2185         </div>
     2186         <div id="message.header.registration">
     2187            <h2 id="rfc.section.10.3"><a href="#rfc.section.10.3">10.3</a>&nbsp;<a href="#message.header.registration">Message Header Registration</a></h2>
     2188            <p id="rfc.section.10.3.p.1">The Message Header Registry located at &lt;<a href="http://www.iana.org/assignments/message-headers/message-header-index.html">http://www.iana.org/assignments/message-headers/message-header-index.html</a>&gt; should be updated with the permanent registrations below (see <a href="#RFC3864" id="rfc.xref.RFC3864.1"><cite title="Registration Procedures for Message Header Fields">[RFC3864]</cite></a>):
     2189            </p>
     2190            <div id="rfc.table.3">
     2191               <div id="iana.header.registration.table"></div>
     2192               <table class="tt full left" cellpadding="3" cellspacing="0">
     2193                  <thead>
     2194                     <tr>
     2195                        <th>Header Field Name</th>
     2196                        <th>Protocol</th>
     2197                        <th>Status</th>
     2198                        <th>Reference</th>
     2199                     </tr>
     2200                  </thead>
     2201                  <tbody>
     2202                     <tr>
     2203                        <td class="left">Allow</td>
     2204                        <td class="left">http</td>
     2205                        <td class="left">standard</td>
     2206                        <td class="left"><a href="#header.allow" id="rfc.xref.header.allow.3" title="Allow">Section&nbsp;9.1</a>
     2207                        </td>
     2208                     </tr>
     2209                     <tr>
     2210                        <td class="left">Expect</td>
     2211                        <td class="left">http</td>
     2212                        <td class="left">standard</td>
     2213                        <td class="left"><a href="#header.expect" id="rfc.xref.header.expect.3" title="Expect">Section&nbsp;9.2</a>
     2214                        </td>
     2215                     </tr>
     2216                     <tr>
     2217                        <td class="left">From</td>
     2218                        <td class="left">http</td>
     2219                        <td class="left">standard</td>
     2220                        <td class="left"><a href="#header.from" id="rfc.xref.header.from.2" title="From">Section&nbsp;9.3</a>
     2221                        </td>
     2222                     </tr>
     2223                     <tr>
     2224                        <td class="left">Location</td>
     2225                        <td class="left">http</td>
     2226                        <td class="left">standard</td>
     2227                        <td class="left"><a href="#header.location" id="rfc.xref.header.location.3" title="Location">Section&nbsp;9.4</a>
     2228                        </td>
     2229                     </tr>
     2230                     <tr>
     2231                        <td class="left">Max-Forwards</td>
     2232                        <td class="left">http</td>
     2233                        <td class="left">standard</td>
     2234                        <td class="left"><a href="#header.max-forwards" id="rfc.xref.header.max-forwards.3" title="Max-Forwards">Section&nbsp;9.5</a>
     2235                        </td>
     2236                     </tr>
     2237                     <tr>
     2238                        <td class="left">Referer</td>
     2239                        <td class="left">http</td>
     2240                        <td class="left">standard</td>
     2241                        <td class="left"><a href="#header.referer" id="rfc.xref.header.referer.2" title="Referer">Section&nbsp;9.6</a>
     2242                        </td>
     2243                     </tr>
     2244                     <tr>
     2245                        <td class="left">Retry-After</td>
     2246                        <td class="left">http</td>
     2247                        <td class="left">standard</td>
     2248                        <td class="left"><a href="#header.retry-after" id="rfc.xref.header.retry-after.2" title="Retry-After">Section&nbsp;9.7</a>
     2249                        </td>
     2250                     </tr>
     2251                     <tr>
     2252                        <td class="left">Server</td>
     2253                        <td class="left">http</td>
     2254                        <td class="left">standard</td>
     2255                        <td class="left"><a href="#header.server" id="rfc.xref.header.server.2" title="Server">Section&nbsp;9.8</a>
     2256                        </td>
     2257                     </tr>
     2258                     <tr>
     2259                        <td class="left">User-Agent</td>
     2260                        <td class="left">http</td>
     2261                        <td class="left">standard</td>
     2262                        <td class="left"><a href="#header.user-agent" id="rfc.xref.header.user-agent.2" title="User-Agent">Section&nbsp;9.9</a>
     2263                        </td>
     2264                     </tr>
     2265                  </tbody>
     2266               </table>
     2267            </div>
     2268            <p id="rfc.section.10.3.p.2">The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".</p>
     2269         </div>
    20032270      </div>
    2004       <h2 id="rfc.section.10.3"><a href="#rfc.section.10.3">10.3</a>&nbsp;<a id="message.header.registration" href="#message.header.registration">Message Header Registration</a></h2>
    2005       <p id="rfc.section.10.3.p.1">The Message Header Registry located at &lt;<a href="http://www.iana.org/assignments/message-headers/message-header-index.html">http://www.iana.org/assignments/message-headers/message-header-index.html</a>&gt; should be updated with the permanent registrations below (see <a href="#RFC3864" id="rfc.xref.RFC3864.1"><cite title="Registration Procedures for Message Header Fields">[RFC3864]</cite></a>):
    2006       </p>
    2007       <div id="rfc.table.3">
    2008          <div id="iana.header.registration.table"></div>
    2009          <table class="tt full left" cellpadding="3" cellspacing="0">
    2010             <thead>
    2011                <tr>
    2012                   <th>Header Field Name</th>
    2013                   <th>Protocol</th>
    2014                   <th>Status</th>
    2015                   <th>Reference</th>
    2016                </tr>
    2017             </thead>
    2018             <tbody>
    2019                <tr>
    2020                   <td class="left">Allow</td>
    2021                   <td class="left">http</td>
    2022                   <td class="left">standard</td>
    2023                   <td class="left"> <a href="#header.allow" id="rfc.xref.header.allow.3" title="Allow">Section&nbsp;9.1</a>
    2024                   </td>
    2025                </tr>
    2026                <tr>
    2027                   <td class="left">Expect</td>
    2028                   <td class="left">http</td>
    2029                   <td class="left">standard</td>
    2030                   <td class="left"> <a href="#header.expect" id="rfc.xref.header.expect.3" title="Expect">Section&nbsp;9.2</a>
    2031                   </td>
    2032                </tr>
    2033                <tr>
    2034                   <td class="left">From</td>
    2035                   <td class="left">http</td>
    2036                   <td class="left">standard</td>
    2037                   <td class="left"> <a href="#header.from" id="rfc.xref.header.from.2" title="From">Section&nbsp;9.3</a>
    2038                   </td>
    2039                </tr>
    2040                <tr>
    2041                   <td class="left">Location</td>
    2042                   <td class="left">http</td>
    2043                   <td class="left">standard</td>
    2044                   <td class="left"> <a href="#header.location" id="rfc.xref.header.location.3" title="Location">Section&nbsp;9.4</a>
    2045                   </td>
    2046                </tr>
    2047                <tr>
    2048                   <td class="left">Max-Forwards</td>
    2049                   <td class="left">http</td>
    2050                   <td class="left">standard</td>
    2051                   <td class="left"> <a href="#header.max-forwards" id="rfc.xref.header.max-forwards.3" title="Max-Forwards">Section&nbsp;9.5</a>
    2052                   </td>
    2053                </tr>
    2054                <tr>
    2055                   <td class="left">Referer</td>
    2056                   <td class="left">http</td>
    2057                   <td class="left">standard</td>
    2058                   <td class="left"> <a href="#header.referer" id="rfc.xref.header.referer.2" title="Referer">Section&nbsp;9.6</a>
    2059                   </td>
    2060                </tr>
    2061                <tr>
    2062                   <td class="left">Retry-After</td>
    2063                   <td class="left">http</td>
    2064                   <td class="left">standard</td>
    2065                   <td class="left"> <a href="#header.retry-after" id="rfc.xref.header.retry-after.2" title="Retry-After">Section&nbsp;9.7</a>
    2066                   </td>
    2067                </tr>
    2068                <tr>
    2069                   <td class="left">Server</td>
    2070                   <td class="left">http</td>
    2071                   <td class="left">standard</td>
    2072                   <td class="left"> <a href="#header.server" id="rfc.xref.header.server.2" title="Server">Section&nbsp;9.8</a>
    2073                   </td>
    2074                </tr>
    2075                <tr>
    2076                   <td class="left">User-Agent</td>
    2077                   <td class="left">http</td>
    2078                   <td class="left">standard</td>
    2079                   <td class="left"> <a href="#header.user-agent" id="rfc.xref.header.user-agent.2" title="User-Agent">Section&nbsp;9.9</a>
    2080                   </td>
    2081                </tr>
    2082             </tbody>
    2083          </table>
     2271      <div id="security.considerations">
     2272         <h1 id="rfc.section.11"><a href="#rfc.section.11">11.</a>&nbsp;<a href="#security.considerations">Security Considerations</a></h1>
     2273         <p id="rfc.section.11.p.1">This section is meant to inform application developers, information providers, and users of the security limitations in HTTP/1.1
     2274            as described by this document. The discussion does not include definitive solutions to the problems revealed, though it does
     2275            make some suggestions for reducing security risks.
     2276         </p>
     2277         <div id="security.sensitive">
     2278            <h2 id="rfc.section.11.1"><a href="#rfc.section.11.1">11.1</a>&nbsp;<a href="#security.sensitive">Transfer of Sensitive Information</a></h2>
     2279            <p id="rfc.section.11.1.p.1">Like any generic data transfer protocol, HTTP cannot regulate the content of the data that is transferred, nor is there any
     2280               a priori method of determining the sensitivity of any particular piece of information within the context of any given request.
     2281               Therefore, applications <em class="bcp14">SHOULD</em> supply as much control over this information as possible to the provider of that information. Four header fields are worth
     2282               special mention in this context: Server, Via, Referer and From.
     2283            </p>
     2284            <p id="rfc.section.11.1.p.2">Revealing the specific software version of the server might allow the server machine to become more vulnerable to attacks
     2285               against software that is known to contain security holes. Implementors <em class="bcp14">SHOULD</em> make the Server header field a configurable option.
     2286            </p>
     2287            <p id="rfc.section.11.1.p.3">Proxies which serve as a portal through a network firewall <em class="bcp14">SHOULD</em> take special precautions regarding the transfer of header information that identifies the hosts behind the firewall. In particular,
     2288               they <em class="bcp14">SHOULD</em> remove, or replace with sanitized versions, any Via fields generated behind the firewall.
     2289            </p>
     2290            <p id="rfc.section.11.1.p.4">The Referer header allows reading patterns to be studied and reverse links drawn. Although it can be very useful, its power
     2291               can be abused if user details are not separated from the information contained in the Referer. Even when the personal information
     2292               has been removed, the Referer header might indicate a private document's URI whose publication would be inappropriate.
     2293            </p>
     2294            <p id="rfc.section.11.1.p.5">The information sent in the From field might conflict with the user's privacy interests or their site's security policy, and
     2295               hence it <em class="bcp14">SHOULD NOT</em> be transmitted without the user being able to disable, enable, and modify the contents of the field. The user <em class="bcp14">MUST</em> be able to set the contents of this field within a user preference or application defaults configuration.
     2296            </p>
     2297            <p id="rfc.section.11.1.p.6">We suggest, though do not require, that a convenient toggle interface be provided for the user to enable or disable the sending
     2298               of From and Referer information.
     2299            </p>
     2300            <p id="rfc.section.11.1.p.7">The User-Agent (<a href="#header.user-agent" id="rfc.xref.header.user-agent.3" title="User-Agent">Section&nbsp;9.9</a>) or Server (<a href="#header.server" id="rfc.xref.header.server.3" title="Server">Section&nbsp;9.8</a>) header fields can sometimes be used to determine that a specific client or server have a particular security hole which
     2301               might be exploited. Unfortunately, this same information is often used for other valuable purposes for which HTTP currently
     2302               has no better mechanism.
     2303            </p>
     2304            <p id="rfc.section.11.1.p.8">Some methods, like TRACE (<a href="#TRACE" id="rfc.xref.TRACE.4" title="TRACE">Section&nbsp;7.8</a>) may expose information sent in request headers in the response entity. Clients <em class="bcp14">SHOULD</em> be careful with sensitive information, like Cookies, Authorization credentials and other headers that might be used to collect
     2305               data from the client.
     2306            </p>
     2307         </div>
     2308         <div id="encoding.sensitive.information.in.uris">
     2309            <h2 id="rfc.section.11.2"><a href="#rfc.section.11.2">11.2</a>&nbsp;<a href="#encoding.sensitive.information.in.uris">Encoding Sensitive Information in URIs</a></h2>
     2310            <p id="rfc.section.11.2.p.1">Because the source of a link might be private information or might reveal an otherwise private information source, it is strongly
     2311               recommended that the user be able to select whether or not the Referer field is sent. For example, a browser client could
     2312               have a toggle switch for browsing openly/anonymously, which would respectively enable/disable the sending of Referer and From
     2313               information.
     2314            </p>
     2315            <p id="rfc.section.11.2.p.2">Clients <em class="bcp14">SHOULD NOT</em> include a Referer header field in a (non-secure) HTTP request if the referring page was transferred with a secure protocol.
     2316            </p>
     2317            <p id="rfc.section.11.2.p.3">Authors of services should not use GET-based forms for the submission of sensitive data because that data will be encoded
     2318               in the request-target. Many existing servers, proxies, and user agents log or display the request-target in places where it
     2319               might be visible to third parties. Such services can use POST-based form submission instead.
     2320            </p>
     2321         </div>
     2322         <div id="location.spoofing">
     2323            <h2 id="rfc.section.11.3"><a href="#rfc.section.11.3">11.3</a>&nbsp;<a href="#location.spoofing">Location Headers and Spoofing</a></h2>
     2324            <p id="rfc.section.11.3.p.1">If a single server supports multiple organizations that do not trust one another, then it <em class="bcp14">MUST</em> check the values of Location and Content-Location headers in responses that are generated under control of said organizations
     2325               to make sure that they do not attempt to invalidate resources over which they have no authority.
     2326            </p>
     2327         </div>
    20842328      </div>
    2085       <p id="rfc.section.10.3.p.2">The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".</p>
    2086       <h1 id="rfc.section.11"><a href="#rfc.section.11">11.</a>&nbsp;<a id="security.considerations" href="#security.considerations">Security Considerations</a></h1>
    2087       <p id="rfc.section.11.p.1">This section is meant to inform application developers, information providers, and users of the security limitations in HTTP/1.1
    2088          as described by this document. The discussion does not include definitive solutions to the problems revealed, though it does
    2089          make some suggestions for reducing security risks.
    2090       </p>
    2091       <h2 id="rfc.section.11.1"><a href="#rfc.section.11.1">11.1</a>&nbsp;<a id="security.sensitive" href="#security.sensitive">Transfer of Sensitive Information</a></h2>
    2092       <p id="rfc.section.11.1.p.1">Like any generic data transfer protocol, HTTP cannot regulate the content of the data that is transferred, nor is there any
    2093          a priori method of determining the sensitivity of any particular piece of information within the context of any given request.
    2094          Therefore, applications <em class="bcp14">SHOULD</em> supply as much control over this information as possible to the provider of that information. Four header fields are worth
    2095          special mention in this context: Server, Via, Referer and From.
    2096       </p>
    2097       <p id="rfc.section.11.1.p.2">Revealing the specific software version of the server might allow the server machine to become more vulnerable to attacks
    2098          against software that is known to contain security holes. Implementors <em class="bcp14">SHOULD</em> make the Server header field a configurable option.
    2099       </p>
    2100       <p id="rfc.section.11.1.p.3">Proxies which serve as a portal through a network firewall <em class="bcp14">SHOULD</em> take special precautions regarding the transfer of header information that identifies the hosts behind the firewall. In particular,
    2101          they <em class="bcp14">SHOULD</em> remove, or replace with sanitized versions, any Via fields generated behind the firewall.
    2102       </p>
    2103       <p id="rfc.section.11.1.p.4">The Referer header allows reading patterns to be studied and reverse links drawn. Although it can be very useful, its power
    2104          can be abused if user details are not separated from the information contained in the Referer. Even when the personal information
    2105          has been removed, the Referer header might indicate a private document's URI whose publication would be inappropriate.
    2106       </p>
    2107       <p id="rfc.section.11.1.p.5">The information sent in the From field might conflict with the user's privacy interests or their site's security policy, and
    2108          hence it <em class="bcp14">SHOULD NOT</em> be transmitted without the user being able to disable, enable, and modify the contents of the field. The user <em class="bcp14">MUST</em> be able to set the contents of this field within a user preference or application defaults configuration.
    2109       </p>
    2110       <p id="rfc.section.11.1.p.6">We suggest, though do not require, that a convenient toggle interface be provided for the user to enable or disable the sending
    2111          of From and Referer information.
    2112       </p>
    2113       <p id="rfc.section.11.1.p.7">The User-Agent (<a href="#header.user-agent" id="rfc.xref.header.user-agent.3" title="User-Agent">Section&nbsp;9.9</a>) or Server (<a href="#header.server" id="rfc.xref.header.server.3" title="Server">Section&nbsp;9.8</a>) header fields can sometimes be used to determine that a specific client or server have a particular security hole which
    2114          might be exploited. Unfortunately, this same information is often used for other valuable purposes for which HTTP currently
    2115          has no better mechanism.
    2116       </p>
    2117       <p id="rfc.section.11.1.p.8">Some methods, like TRACE (<a href="#TRACE" id="rfc.xref.TRACE.4" title="TRACE">Section&nbsp;7.8</a>) may expose information sent in request headers in the response entity. Clients <em class="bcp14">SHOULD</em> be careful with sensitive information, like Cookies, Authorization credentials and other headers that might be used to collect
    2118          data from the client.
    2119       </p>
    2120       <h2 id="rfc.section.11.2"><a href="#rfc.section.11.2">11.2</a>&nbsp;<a id="encoding.sensitive.information.in.uris" href="#encoding.sensitive.information.in.uris">Encoding Sensitive Information in URIs</a></h2>
    2121       <p id="rfc.section.11.2.p.1">Because the source of a link might be private information or might reveal an otherwise private information source, it is strongly
    2122          recommended that the user be able to select whether or not the Referer field is sent. For example, a browser client could
    2123          have a toggle switch for browsing openly/anonymously, which would respectively enable/disable the sending of Referer and From
    2124          information.
    2125       </p>
    2126       <p id="rfc.section.11.2.p.2">Clients <em class="bcp14">SHOULD NOT</em> include a Referer header field in a (non-secure) HTTP request if the referring page was transferred with a secure protocol.
    2127       </p>
    2128       <p id="rfc.section.11.2.p.3">Authors of services should not use GET-based forms for the submission of sensitive data because that data will be encoded
    2129          in the request-target. Many existing servers, proxies, and user agents log or display the request-target in places where it
    2130          might be visible to third parties. Such services can use POST-based form submission instead.
    2131       </p>
    2132       <h2 id="rfc.section.11.3"><a href="#rfc.section.11.3">11.3</a>&nbsp;<a id="location.spoofing" href="#location.spoofing">Location Headers and Spoofing</a></h2>
    2133       <p id="rfc.section.11.3.p.1">If a single server supports multiple organizations that do not trust one another, then it <em class="bcp14">MUST</em> check the values of Location and Content-Location headers in responses that are generated under control of said organizations
    2134          to make sure that they do not attempt to invalidate resources over which they have no authority.
    2135       </p>
    2136       <h1 id="rfc.section.12"><a href="#rfc.section.12">12.</a>&nbsp;<a id="ack" href="#ack">Acknowledgments</a></h1>
     2329      <div id="ack">
     2330         <h1 id="rfc.section.12"><a href="#rfc.section.12">12.</a>&nbsp;<a href="#ack">Acknowledgments</a></h1>
     2331      </div>
    21372332      <h1 id="rfc.references"><a id="rfc.section.13" href="#rfc.section.13">13.</a> References
    21382333      </h1>
    21392334      <h2 id="rfc.references.1"><a href="#rfc.section.13.1" id="rfc.section.13.1">13.1</a> Normative References
    21402335      </h2>
    2141       <table>                 
     2336      <table>
    21422337         <tr>
    21432338            <td class="reference"><b id="Part1">[Part1]</b></td>
    2144             <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-10">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p1-messaging-10 (work in progress), July&nbsp;2010.
     2339            <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-10">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p1-messaging-10 (work in progress), July&nbsp;2010.
    21452340            </td>
    21462341         </tr>
    21472342         <tr>
    21482343            <td class="reference"><b id="Part3">[Part3]</b></td>
    2149             <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p3-payload-10">HTTP/1.1, part 3: Message Payload and Content Negotiation</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p3-payload-10 (work in progress), July&nbsp;2010.
     2344            <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-p3-payload-10">HTTP/1.1, part 3: Message Payload and Content Negotiation</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p3-payload-10 (work in progress), July&nbsp;2010.
    21502345            </td>
    21512346         </tr>
    21522347         <tr>
    21532348            <td class="reference"><b id="Part4">[Part4]</b></td>
    2154             <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p4-conditional-10">HTTP/1.1, part 4: Conditional Requests</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p4-conditional-10 (work in progress), July&nbsp;2010.
     2349            <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-p4-conditional-10">HTTP/1.1, part 4: Conditional Requests</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p4-conditional-10 (work in progress), July&nbsp;2010.
    21552350            </td>
    21562351         </tr>
    21572352         <tr>
    21582353            <td class="reference"><b id="Part5">[Part5]</b></td>
    2159             <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p5-range-10">HTTP/1.1, part 5: Range Requests and Partial Responses</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p5-range-10 (work in progress), July&nbsp;2010.
     2354            <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-p5-range-10">HTTP/1.1, part 5: Range Requests and Partial Responses</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p5-range-10 (work in progress), July&nbsp;2010.
    21602355            </td>
    21612356         </tr>
    21622357         <tr>
    21632358            <td class="reference"><b id="Part6">[Part6]</b></td>
    2164             <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, <a href="mailto:mnot@mnot.net">Nottingham, M., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p6-cache-10">HTTP/1.1, part 6: Caching</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p6-cache-10 (work in progress), July&nbsp;2010.
     2359            <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, <a href="mailto:mnot@mnot.net">Nottingham, M., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-p6-cache-10">HTTP/1.1, part 6: Caching</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p6-cache-10 (work in progress), July&nbsp;2010.
    21652360            </td>
    21662361         </tr>
    21672362         <tr>
    21682363            <td class="reference"><b id="Part7">[Part7]</b></td>
    2169             <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p7-auth-10">HTTP/1.1, part 7: Authentication</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p7-auth-10 (work in progress), July&nbsp;2010.
     2364            <td class="top"><a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R., Ed.</a>, <a href="mailto:jg@freedesktop.org" title="Alcatel-Lucent Bell Labs">Gettys, J.</a>, <a href="mailto:JeffMogul@acm.org" title="Hewlett-Packard Company">Mogul, J.</a>, <a href="mailto:henrikn@microsoft.com" title="Microsoft Corporation">Frystyk, H.</a>, <a href="mailto:LMM@acm.org" title="Adobe Systems, Incorporated">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, <a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:ylafon@w3.org" title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-p7-auth-10">HTTP/1.1, part 7: Authentication</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p7-auth-10 (work in progress), July&nbsp;2010.
    21702365            </td>
    21712366         </tr>
    21722367         <tr>
    21732368            <td class="reference"><b id="RFC2119">[RFC2119]</b></td>
    2174             <td class="top"><a href="mailto:sob@harvard.edu" title="Harvard University">Bradner, S.</a>, “<a href="http://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a>”, BCP&nbsp;14, RFC&nbsp;2119, March&nbsp;1997.
     2369            <td class="top"><a href="mailto:sob@harvard.edu" title="Harvard University">Bradner, S.</a>, “<a href="https://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a>”, BCP&nbsp;14, RFC&nbsp;2119, March&nbsp;1997.
    21752370            </td>
    21762371         </tr>
    21772372         <tr>
    21782373            <td class="reference"><b id="RFC3986">[RFC3986]</b></td>
    2179             <td class="top"><a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R.</a>, and <a href="mailto:LMM@acm.org" title="Adobe Systems Incorporated">L. Masinter</a>, “<a href="http://tools.ietf.org/html/rfc3986">Uniform Resource Identifier (URI): Generic Syntax</a>”, RFC&nbsp;3986, STD&nbsp;66, January&nbsp;2005.
     2374            <td class="top"><a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R.</a>, and <a href="mailto:LMM@acm.org" title="Adobe Systems Incorporated">L. Masinter</a>, “<a href="https://tools.ietf.org/html/rfc3986">Uniform Resource Identifier (URI): Generic Syntax</a>”, RFC&nbsp;3986, STD&nbsp;66, January&nbsp;2005.
    21802375            </td>
    21812376         </tr>
    21822377         <tr>
    21832378            <td class="reference"><b id="RFC5234">[RFC5234]</b></td>
    2184             <td class="top"><a href="mailto:dcrocker@bbiw.net" title="Brandenburg InternetWorking">Crocker, D., Ed.</a> and <a href="mailto:paul.overell@thus.net" title="THUS plc.">P. Overell</a>, “<a href="http://tools.ietf.org/html/rfc5234">Augmented BNF for Syntax Specifications: ABNF</a>”, STD&nbsp;68, RFC&nbsp;5234, January&nbsp;2008.
     2379            <td class="top"><a href="mailto:dcrocker@bbiw.net" title="Brandenburg InternetWorking">Crocker, D., Ed.</a> and <a href="mailto:paul.overell@thus.net" title="THUS plc.">P. Overell</a>, “<a href="https://tools.ietf.org/html/rfc5234">Augmented BNF for Syntax Specifications: ABNF</a>”, STD&nbsp;68, RFC&nbsp;5234, January&nbsp;2008.
    21852380            </td>
    21862381         </tr>
    … …  
    21882383      <h2 id="rfc.references.2"><a href="#rfc.section.13.2" id="rfc.section.13.2">13.2</a> Informative References
    21892384      </h2>
    2190       <table>             
     2385      <table>
    21912386         <tr>
    21922387            <td class="reference"><b id="RFC1945">[RFC1945]</b></td>
    2193             <td class="top"><a href="mailto:timbl@w3.org" title="MIT, Laboratory for Computer Science">Berners-Lee, T.</a>, <a href="mailto:fielding@ics.uci.edu" title="University of California, Irvine, Department of Information and Computer Science">Fielding, R.</a>, and <a href="mailto:frystyk@w3.org" title="W3 Consortium, MIT Laboratory for Computer Science">H. Nielsen</a>, “<a href="http://tools.ietf.org/html/rfc1945">Hypertext Transfer Protocol -- HTTP/1.0</a>”, RFC&nbsp;1945, May&nbsp;1996.
     2388            <td class="top"><a href="mailto:timbl@w3.org" title="MIT, Laboratory for Computer Science">Berners-Lee, T.</a>, <a href="mailto:fielding@ics.uci.edu" title="University of California, Irvine, Department of Information and Computer Science">Fielding, R.</a>, and <a href="mailto:frystyk@w3.org" title="W3 Consortium, MIT Laboratory for Computer Science">H. Nielsen</a>, “<a href="https://tools.ietf.org/html/rfc1945">Hypertext Transfer Protocol -- HTTP/1.0</a>”, RFC&nbsp;1945, May&nbsp;1996.
    21942389            </td>
    21952390         </tr>
    21962391         <tr>
    21972392            <td class="reference"><b id="RFC2068">[RFC2068]</b></td>
    2198             <td class="top"><a href="mailto:fielding@ics.uci.edu" title="University of California, Irvine, Department of Information and Computer Science">Fielding, R.</a>, <a href="mailto:jg@w3.org" title="MIT Laboratory for Computer Science">Gettys, J.</a>, <a href="mailto:mogul@wrl.dec.com" title="Digital Equipment Corporation, Western Research Laboratory">Mogul, J.</a>, <a href="mailto:frystyk@w3.org" title="MIT Laboratory for Computer Science">Nielsen, H.</a>, and <a href="mailto:timbl@w3.org" title="MIT Laboratory for Computer Science">T. Berners-Lee</a>, “<a href="http://tools.ietf.org/html/rfc2068">Hypertext Transfer Protocol -- HTTP/1.1</a>”, RFC&nbsp;2068, January&nbsp;1997.
     2393            <td class="top"><a href="mailto:fielding@ics.uci.edu" title="University of California, Irvine, Department of Information and Computer Science">Fielding, R.</a>, <a href="mailto:jg@w3.org" title="MIT Laboratory for Computer Science">Gettys, J.</a>, <a href="mailto:mogul@wrl.dec.com" title="Digital Equipment Corporation, Western Research Laboratory">Mogul, J.</a>, <a href="mailto:frystyk@w3.org" title="MIT Laboratory for Computer Science">Nielsen, H.</a>, and <a href="mailto:timbl@w3.org" title="MIT Laboratory for Computer Science">T. Berners-Lee</a>, “<a href="https://tools.ietf.org/html/rfc2068">Hypertext Transfer Protocol -- HTTP/1.1</a>”, RFC&nbsp;2068, January&nbsp;1997.
    21992394            </td>
    22002395         </tr>
    22012396         <tr>
    22022397            <td class="reference"><b id="RFC2616">[RFC2616]</b></td>
    2203             <td class="top"><a href="mailto:fielding@ics.uci.edu" title="University of California, Irvine">Fielding, R.</a>, <a href="mailto:jg@w3.org" title="W3C">Gettys, J.</a>, <a href="mailto:mogul@wrl.dec.com" title="Compaq Computer Corporation">Mogul, J.</a>, <a href="mailto:frystyk@w3.org" title="MIT Laboratory for Computer Science">Frystyk, H.</a>, <a href="mailto:masinter@parc.xerox.com" title="Xerox Corporation">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, and <a href="mailto:timbl@w3.org" title="W3C">T. Berners-Lee</a>, “<a href="http://tools.ietf.org/html/rfc2616">Hypertext Transfer Protocol -- HTTP/1.1</a>”, RFC&nbsp;2616, June&nbsp;1999.
     2398            <td class="top"><a href="mailto:fielding@ics.uci.edu" title="University of California, Irvine">Fielding, R.</a>, <a href="mailto:jg@w3.org" title="W3C">Gettys, J.</a>, <a href="mailto:mogul@wrl.dec.com" title="Compaq Computer Corporation">Mogul, J.</a>, <a href="mailto:frystyk@w3.org" title="MIT Laboratory for Computer Science">Frystyk, H.</a>, <a href="mailto:masinter@parc.xerox.com" title="Xerox Corporation">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, and <a href="mailto:timbl@w3.org" title="W3C">T. Berners-Lee</a>, “<a href="https://tools.ietf.org/html/rfc2616">Hypertext Transfer Protocol -- HTTP/1.1</a>”, RFC&nbsp;2616, June&nbsp;1999.
    22042399            </td>
    22052400         </tr>
    22062401         <tr>
    22072402            <td class="reference"><b id="RFC2817">[RFC2817]</b></td>
    2208             <td class="top"><a href="mailto:rohit@4K-associates.com" title="4K Associates / UC Irvine">Khare, R.</a> and <a href="mailto:lawrence@agranat.com" title="Agranat Systems, Inc.">S. Lawrence</a>, “<a href="http://tools.ietf.org/html/rfc2817">Upgrading to TLS Within HTTP/1.1</a>”, RFC&nbsp;2817, May&nbsp;2000.
     2403            <td class="top"><a href="mailto:rohit@4K-associates.com" title="4K Associates / UC Irvine">Khare, R.</a> and <a href="mailto:lawrence@agranat.com" title="Agranat Systems, Inc.">S. Lawrence</a>, “<a href="https://tools.ietf.org/html/rfc2817">Upgrading to TLS Within HTTP/1.1</a>”, RFC&nbsp;2817, May&nbsp;2000.
    22092404            </td>
    22102405         </tr>
    22112406         <tr>
    22122407            <td class="reference"><b id="RFC3864">[RFC3864]</b></td>
    2213             <td class="top"><a href="mailto:GK-IETF@ninebynine.org" title="Nine by Nine">Klyne, G.</a>, <a href="mailto:mnot@pobox.com" title="BEA Systems">Nottingham, M.</a>, and <a href="mailto:JeffMogul@acm.org" title="HP Labs">J. Mogul</a>, “<a href="http://tools.ietf.org/html/rfc3864">Registration Procedures for Message Header Fields</a>”, BCP&nbsp;90, RFC&nbsp;3864, September&nbsp;2004.
     2408            <td class="top"><a href="mailto:GK-IETF@ninebynine.org" title="Nine by Nine">Klyne, G.</a>, <a href="mailto:mnot@pobox.com" title="BEA Systems">Nottingham, M.</a>, and <a href="mailto:JeffMogul@acm.org" title="HP Labs">J. Mogul</a>, “<a href="https://tools.ietf.org/html/rfc3864">Registration Procedures for Message Header Fields</a>”, BCP&nbsp;90, RFC&nbsp;3864, September&nbsp;2004.
    22142409            </td>
    22152410         </tr>
    22162411         <tr>
    22172412            <td class="reference"><b id="RFC5226">[RFC5226]</b></td>
    2218             <td class="top"><a href="mailto:narten@us.ibm.com" title="IBM">Narten, T.</a> and <a href="mailto:Harald@Alvestrand.no" title="Google">H. Alvestrand</a>, “<a href="http://tools.ietf.org/html/rfc5226">Guidelines for Writing an IANA Considerations Section in RFCs</a>”, BCP&nbsp;26, RFC&nbsp;5226, May&nbsp;2008.
     2413            <td class="top"><a href="mailto:narten@us.ibm.com" title="IBM">Narten, T.</a> and <a href="mailto:Harald@Alvestrand.no" title="Google">H. Alvestrand</a>, “<a href="https://tools.ietf.org/html/rfc5226">Guidelines for Writing an IANA Considerations Section in RFCs</a>”, BCP&nbsp;26, RFC&nbsp;5226, May&nbsp;2008.
    22192414            </td>
    22202415         </tr>
    22212416         <tr>
    22222417            <td class="reference"><b id="RFC5322">[RFC5322]</b></td>
    2223             <td class="top">Resnick, P., “<a href="http://tools.ietf.org/html/rfc5322">Internet Message Format</a>”, RFC&nbsp;5322, October&nbsp;2008.
     2418            <td class="top">Resnick, P., “<a href="https://tools.ietf.org/html/rfc5322">Internet Message Format</a>”, RFC&nbsp;5322, October&nbsp;2008.
    22242419            </td>
    22252420         </tr>
    22262421      </table>
    2227       <div class="avoidbreak">
    2228          <h1 id="rfc.authors"><a href="#rfc.authors">Authors' Addresses</a></h1>
    2229          <address class="vcard"><span class="vcardline"><span class="fn">Roy T. Fielding</span>
    2230                (editor)
    2231                <span class="n hidden"><span class="family-name">Fielding</span><span class="given-name">Roy T.</span></span></span><span class="org vcardline">Day Software</span><span class="adr"><span class="street-address vcardline">23 Corporate Plaza DR, Suite 280</span><span class="vcardline"><span class="locality">Newport Beach</span>, <span class="region">CA</span>&nbsp;<span class="postal-code">92660</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline tel">Phone: <a href="tel:+1-949-706-5300"><span class="value">+1-949-706-5300</span></a></span><span class="vcardline tel"><span class="type">Fax</span>: <a href="fax:+1-949-706-5305"><span class="value">+1-949-706-5305</span></a></span><span class="vcardline">Email: <a href="mailto:fielding@gbiv.com"><span class="email">fielding@gbiv.com</span></a></span><span class="vcardline">URI: <a href="http://roy.gbiv.com/" class="url">http://roy.gbiv.com/</a></span></address>
    2232          <address class="vcard"><span class="vcardline"><span class="fn">Jim Gettys</span><span class="n hidden"><span class="family-name">Gettys</span><span class="given-name">Jim</span></span></span><span class="org vcardline">Alcatel-Lucent Bell Labs</span><span class="adr"><span class="street-address vcardline">21 Oak Knoll Road</span><span class="vcardline"><span class="locality">Carlisle</span>, <span class="region">MA</span>&nbsp;<span class="postal-code">01741</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">Email: <a href="mailto:jg@freedesktop.org"><span class="email">jg@freedesktop.org</span></a></span><span class="vcardline">URI: <a href="http://gettys.wordpress.com/" class="url">http://gettys.wordpress.com/</a></span></address>
    2233          <address class="vcard"><span class="vcardline"><span class="fn">Jeffrey C. Mogul</span><span class="n hidden"><span class="family-name">Mogul</span><span class="given-name">Jeffrey C.</span></span></span><span class="org vcardline">Hewlett-Packard Company</span><span class="adr"><span class="street-address vcardline">HP Labs, Large Scale Systems Group</span><span class="street-address vcardline">1501 Page Mill Road, MS 1177</span><span class="vcardline"><span class="locality">Palo Alto</span>, <span class="region">CA</span>&nbsp;<span class="postal-code">94304</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">Email: <a href="mailto:JeffMogul@acm.org"><span class="email">JeffMogul@acm.org</span></a></span></address>
    2234          <address class="vcard"><span class="vcardline"><span class="fn">Henrik Frystyk Nielsen</span><span class="n hidden"><span class="family-name">Frystyk</span></span></span><span class="org vcardline">Microsoft Corporation</span><span class="adr"><span class="street-address vcardline">1 Microsoft Way</span><span class="vcardline"><span class="locality">Redmond</span>, <span class="region">WA</span>&nbsp;<span class="postal-code">98052</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">Email: <a href="mailto:henrikn@microsoft.com"><span class="email">henrikn@microsoft.com</span></a></span></address>
    2235          <address class="vcard"><span class="vcardline"><span class="fn">Larry Masinter</span><span class="n hidden"><span class="family-name">Masinter</span><span class="given-name">Larry</span></span></span><span class="org vcardline">Adobe Systems, Incorporated</span><span class="adr"><span class="street-address vcardline">345 Park Ave</span><span class="vcardline"><span class="locality">San Jose</span>, <span class="region">CA</span>&nbsp;<span class="postal-code">95110</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">Email: <a href="mailto:LMM@acm.org"><span class="email">LMM@acm.org</span></a></span><span class="vcardline">URI: <a href="http://larry.masinter.net/" class="url">http://larry.masinter.net/</a></span></address>
    2236          <address class="vcard"><span class="vcardline"><span class="fn">Paul J. Leach</span><span class="n hidden"><span class="family-name">Leach</span><span class="given-name">Paul J.</span></span></span><span class="org vcardline">Microsoft Corporation</span><span class="adr"><span class="street-address vcardline">1 Microsoft Way</span><span class="vcardline"><span class="locality">Redmond</span>, <span class="region">WA</span>&nbsp;<span class="postal-code">98052</span></span></span><span class="vcardline">Email: <a href="mailto:paulle@microsoft.com"><span class="email">paulle@microsoft.com</span></a></span></address>
    2237          <address class="vcard"><span class="vcardline"><span class="fn">Tim Berners-Lee</span><span class="n hidden"><span class="family-name">Berners-Lee</span><span class="given-name">Tim</span></span></span><span class="org vcardline">World Wide Web Consortium</span><span class="adr"><span class="street-address vcardline">MIT Computer Science and Artificial Intelligence Laboratory</span><span class="street-address vcardline">The Stata Center, Building 32</span><span class="street-address vcardline">32 Vassar Street</span><span class="vcardline"><span class="locality">Cambridge</span>, <span class="region">MA</span>&nbsp;<span class="postal-code">02139</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">Email: <a href="mailto:timbl@w3.org"><span class="email">timbl@w3.org</span></a></span><span class="vcardline">URI: <a href="http://www.w3.org/People/Berners-Lee/" class="url">http://www.w3.org/People/Berners-Lee/</a></span></address>
    2238          <address class="vcard"><span class="vcardline"><span class="fn">Yves Lafon</span>
    2239                (editor)
    2240                <span class="n hidden"><span class="family-name">Lafon</span><span class="given-name">Yves</span></span></span><span class="org vcardline">World Wide Web Consortium</span><span class="adr"><span class="street-address vcardline">W3C / ERCIM</span><span class="street-address vcardline">2004, rte des Lucioles</span><span class="vcardline"><span class="locality">Sophia-Antipolis</span>, <span class="region">AM</span>&nbsp;<span class="postal-code">06902</span></span><span class="country-name vcardline">France</span></span><span class="vcardline">Email: <a href="mailto:ylafon@w3.org"><span class="email">ylafon@w3.org</span></a></span><span class="vcardline">URI: <a href="http://www.raubacapeu.net/people/yves/" class="url">http://www.raubacapeu.net/people/yves/</a></span></address>
    2241          <address class="vcard"><span class="vcardline"><span class="fn">Julian F. Reschke</span>
    2242                (editor)
    2243                <span class="n hidden"><span class="family-name">Reschke</span><span class="given-name">Julian F.</span></span></span><span class="org vcardline">greenbytes GmbH</span><span class="adr"><span class="street-address vcardline">Hafenweg 16</span><span class="vcardline"><span class="locality">Muenster</span>, <span class="region">NW</span>&nbsp;<span class="postal-code">48155</span></span><span class="country-name vcardline">Germany</span></span><span class="vcardline tel">Phone: <a href="tel:+492512807760"><span class="value">+49 251 2807760</span></a></span><span class="vcardline tel"><span class="type">Fax</span>: <a href="fax:+492512807761"><span class="value">+49 251 2807761</span></a></span><span class="vcardline">Email: <a href="mailto:julian.reschke@greenbytes.de"><span class="email">julian.reschke@greenbytes.de</span></a></span><span class="vcardline">URI: <a href="http://greenbytes.de/tech/webdav/" class="url">http://greenbytes.de/tech/webdav/</a></span></address>
     2422      <div id="compatibility">
     2423         <h1 id="rfc.section.A" class="np"><a href="#rfc.section.A">A.</a>&nbsp;<a href="#compatibility">Compatibility with Previous Versions</a></h1>
     2424         <div id="changes.from.rfc.2068">
     2425            <h2 id="rfc.section.A.1"><a href="#rfc.section.A.1">A.1</a>&nbsp;<a href="#changes.from.rfc.2068">Changes from RFC 2068</a></h2>
     2426            <p id="rfc.section.A.1.p.1">Clarified which error code should be used for inbound server failures (e.g., DNS failures). (<a href="#status.504" id="rfc.xref.status.504.3" title="504 Gateway Timeout">Section&nbsp;8.5.5</a>).
     2427            </p>
     2428            <p id="rfc.section.A.1.p.2">201 (Created) had a race that required an Etag be sent when a resource is first created. (<a href="#status.201" id="rfc.xref.status.201.3" title="201 Created">Section&nbsp;8.2.2</a>).
     2429            </p>
     2430            <p id="rfc.section.A.1.p.3">303 (See Also) and 307 (Temporary Redirect) added to address user agent failure to implement status code 302 properly. (Section <a href="#status.303" id="rfc.xref.status.303.4" title="303 See Other">8.3.4</a> and <a href="#status.307" id="rfc.xref.status.307.4" title="307 Temporary Redirect">8.3.8</a>)
     2431            </p>
     2432            <p id="rfc.section.A.1.p.4">Rewrite of message transmission requirements to make it much harder for implementors to get it wrong, as the consequences
     2433               of errors here can have significant impact on the Internet, and to deal with the following problems:
     2434            </p>
     2435            <ol>
     2436               <li>Changing "HTTP/1.1 or later" to "HTTP/1.1", in contexts where this was incorrectly placing a requirement on the behavior of
     2437                  an implementation of a future version of HTTP/1.x
     2438               </li>
     2439               <li>Made it clear that user-agents should retry requests, not "clients" in general.</li>
     2440               <li>Converted requirements for clients to ignore unexpected 100 (Continue) responses, and for proxies to forward 100 responses,
     2441                  into a general requirement for 1xx responses.
     2442               </li>
     2443               <li>Modified some TCP-specific language, to make it clearer that non-TCP transports are possible for HTTP.</li>
     2444               <li>Require that the origin server <em class="bcp14">MUST NOT</em> wait for the request body before it sends a required 100 (Continue) response.
     2445               </li>
     2446               <li>Allow, rather than require, a server to omit 100 (Continue) if it has already seen some of the request body.</li>
     2447               <li>Allow servers to defend against denial-of-service attacks and broken clients.</li>
     2448            </ol>
     2449            <p id="rfc.section.A.1.p.5">This change adds the Expect header and 417 status code.</p>
     2450            <p id="rfc.section.A.1.p.6">Clean up confusion between 403 and 404 responses. (Section <a href="#status.403" id="rfc.xref.status.403.3" title="403 Forbidden">8.4.4</a>, <a href="#status.404" id="rfc.xref.status.404.3" title="404 Not Found">8.4.5</a>, and <a href="#status.410" id="rfc.xref.status.410.3" title="410 Gone">8.4.11</a>)
     2451            </p>
     2452            <p id="rfc.section.A.1.p.7">The PATCH<span id="rfc.iref.p.3"></span><span id="rfc.iref.m.10"></span>, LINK<span id="rfc.iref.l.2"></span><span id="rfc.iref.m.11"></span>, UNLINK<span id="rfc.iref.u.2"></span><span id="rfc.iref.m.12"></span> methods were defined but not commonly implemented in previous versions of this specification. See <a href="https://tools.ietf.org/html/rfc2068#section-19.6.1">Section 19.6.1</a> of <a href="#RFC2068" id="rfc.xref.RFC2068.3"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a>.
     2453            </p>
     2454         </div>
     2455         <div id="changes.from.rfc.2616">
     2456            <h2 id="rfc.section.A.2"><a href="#rfc.section.A.2">A.2</a>&nbsp;<a href="#changes.from.rfc.2616">Changes from RFC 2616</a></h2>
     2457            <p id="rfc.section.A.2.p.1">This document takes over the Status Code Registry, previously defined in <a href="https://tools.ietf.org/html/rfc2817#section-7.1">Section 7.1</a> of <a href="#RFC2817" id="rfc.xref.RFC2817.3"><cite title="Upgrading to TLS Within HTTP/1.1">[RFC2817]</cite></a>. (<a href="#status.code.registry" title="Status Code Registry">Section&nbsp;4.1</a>)
     2458            </p>
     2459            <p id="rfc.section.A.2.p.2">Clarify definition of POST. (<a href="#POST" id="rfc.xref.POST.3" title="POST">Section&nbsp;7.5</a>)
     2460            </p>
     2461            <p id="rfc.section.A.2.p.3">Failed to consider that there are many other request methods that are safe to automatically redirect, and further that the
     2462               user agent is able to make that determination based on the request method semantics. (Sections <a href="#status.301" id="rfc.xref.status.301.3" title="301 Moved Permanently">8.3.2</a>, <a href="#status.302" id="rfc.xref.status.302.3" title="302 Found">8.3.3</a> and <a href="#status.307" id="rfc.xref.status.307.5" title="307 Temporary Redirect">8.3.8</a>)
     2463            </p>
     2464            <p id="rfc.section.A.2.p.4">Deprecate 305 Use Proxy status code, because user agents did not implement it. It used to indicate that the requested resource
     2465               must be accessed through the proxy given by the Location field. The Location field gave the URI of the proxy. The recipient
     2466               was expected to repeat this single request via the proxy. (<a href="#status.305" id="rfc.xref.status.305.3" title="305 Use Proxy">Section&nbsp;8.3.6</a>)
     2467            </p>
     2468            <p id="rfc.section.A.2.p.5">Reclassify Allow header as response header, removing the option to specify it in a PUT request. Relax the server requirement
     2469               on the contents of the Allow header and remove requirement on clients to always trust the header value. (<a href="#header.allow" id="rfc.xref.header.allow.4" title="Allow">Section&nbsp;9.1</a>)
     2470            </p>
     2471            <p id="rfc.section.A.2.p.6">Correct syntax of Location header to allow URI references (including relative references and fragments), as referred symbol
     2472               "absoluteURI" wasn't what was expected, and add some clarifications as to when use of fragments would not be appropriate.
     2473               (<a href="#header.location" id="rfc.xref.header.location.4" title="Location">Section&nbsp;9.4</a>)
     2474            </p>
     2475            <p id="rfc.section.A.2.p.7">Allow Referer value of "about:blank" as alternative to not specifying it. (<a href="#header.referer" id="rfc.xref.header.referer.3" title="Referer">Section&nbsp;9.6</a>)
     2476            </p>
     2477            <p id="rfc.section.A.2.p.8">In the description of the Server header, the Via field was described as a SHOULD. The requirement was and is stated correctly
     2478               in the description of the Via header in <a href="p1-messaging.html#header.via" title="Via">Section 9.9</a> of <a href="#Part1" id="rfc.xref.Part1.34"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>. (<a href="#header.server" id="rfc.xref.header.server.4" title="Server">Section&nbsp;9.8</a>)
     2479            </p>
     2480         </div>
    22442481      </div>
    2245       <h1 id="rfc.section.A" class="np"><a href="#rfc.section.A">A.</a>&nbsp;<a id="compatibility" href="#compatibility">Compatibility with Previous Versions</a></h1>
    2246       <h2 id="rfc.section.A.1"><a href="#rfc.section.A.1">A.1</a>&nbsp;<a id="changes.from.rfc.2068" href="#changes.from.rfc.2068">Changes from RFC 2068</a></h2>
    2247       <p id="rfc.section.A.1.p.1">Clarified which error code should be used for inbound server failures (e.g., DNS failures). (<a href="#status.504" id="rfc.xref.status.504.3" title="504 Gateway Timeout">Section&nbsp;8.5.5</a>).
    2248       </p>
    2249       <p id="rfc.section.A.1.p.2">201 (Created) had a race that required an Etag be sent when a resource is first created. (<a href="#status.201" id="rfc.xref.status.201.3" title="201 Created">Section&nbsp;8.2.2</a>).
    2250       </p>
    2251       <p id="rfc.section.A.1.p.3">303 (See Also) and 307 (Temporary Redirect) added to address user agent failure to implement status code 302 properly. (Section <a href="#status.303" id="rfc.xref.status.303.4" title="303 See Other">8.3.4</a> and <a href="#status.307" id="rfc.xref.status.307.4" title="307 Temporary Redirect">8.3.8</a>)
    2252       </p>
    2253       <p id="rfc.section.A.1.p.4">Rewrite of message transmission requirements to make it much harder for implementors to get it wrong, as the consequences
    2254          of errors here can have significant impact on the Internet, and to deal with the following problems:
    2255       </p>
    2256       <ol>
    2257          <li>Changing "HTTP/1.1 or later" to "HTTP/1.1", in contexts where this was incorrectly placing a requirement on the behavior of
    2258             an implementation of a future version of HTTP/1.x
    2259          </li>
    2260          <li>Made it clear that user-agents should retry requests, not "clients" in general.</li>
    2261          <li>Converted requirements for clients to ignore unexpected 100 (Continue) responses, and for proxies to forward 100 responses,
    2262             into a general requirement for 1xx responses.
    2263          </li>
    2264          <li>Modified some TCP-specific language, to make it clearer that non-TCP transports are possible for HTTP.</li>
    2265          <li>Require that the origin server <em class="bcp14">MUST NOT</em> wait for the request body before it sends a required 100 (Continue) response.
    2266          </li>
    2267          <li>Allow, rather than require, a server to omit 100 (Continue) if it has already seen some of the request body.</li>
    2268          <li>Allow servers to defend against denial-of-service attacks and broken clients.</li>
    2269       </ol>
    2270       <p id="rfc.section.A.1.p.5">This change adds the Expect header and 417 status code.</p>
    2271       <p id="rfc.section.A.1.p.6">Clean up confusion between 403 and 404 responses. (Section <a href="#status.403" id="rfc.xref.status.403.3" title="403 Forbidden">8.4.4</a>, <a href="#status.404" id="rfc.xref.status.404.3" title="404 Not Found">8.4.5</a>, and <a href="#status.410" id="rfc.xref.status.410.3" title="410 Gone">8.4.11</a>)
    2272       </p>
    2273       <p id="rfc.section.A.1.p.7">The PATCH<span id="rfc.iref.p.3"></span><span id="rfc.iref.m.10"></span>, LINK<span id="rfc.iref.l.2"></span><span id="rfc.iref.m.11"></span>, UNLINK<span id="rfc.iref.u.2"></span><span id="rfc.iref.m.12"></span> methods were defined but not commonly implemented in previous versions of this specification. See <a href="http://tools.ietf.org/html/rfc2068#section-19.6.1">Section 19.6.1</a> of <a href="#RFC2068" id="rfc.xref.RFC2068.3"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a>.
    2274       </p>
    2275       <h2 id="rfc.section.A.2"><a href="#rfc.section.A.2">A.2</a>&nbsp;<a id="changes.from.rfc.2616" href="#changes.from.rfc.2616">Changes from RFC 2616</a></h2>
    2276       <p id="rfc.section.A.2.p.1">This document takes over the Status Code Registry, previously defined in <a href="http://tools.ietf.org/html/rfc2817#section-7.1">Section 7.1</a> of <a href="#RFC2817" id="rfc.xref.RFC2817.3"><cite title="Upgrading to TLS Within HTTP/1.1">[RFC2817]</cite></a>. (<a href="#status.code.registry" title="Status Code Registry">Section&nbsp;4.1</a>)
    2277       </p>
    2278       <p id="rfc.section.A.2.p.2">Clarify definition of POST. (<a href="#POST" id="rfc.xref.POST.3" title="POST">Section&nbsp;7.5</a>)
    2279       </p>
    2280       <p id="rfc.section.A.2.p.3">Failed to consider that there are many other request methods that are safe to automatically redirect, and further that the
    2281          user agent is able to make that determination based on the request method semantics. (Sections <a href="#status.301" id="rfc.xref.status.301.3" title="301 Moved Permanently">8.3.2</a>, <a href="#status.302" id="rfc.xref.status.302.3" title="302 Found">8.3.3</a> and <a href="#status.307" id="rfc.xref.status.307.5" title="307 Temporary Redirect">8.3.8</a>)
    2282       </p>
    2283       <p id="rfc.section.A.2.p.4">Deprecate 305 Use Proxy status code, because user agents did not implement it. It used to indicate that the requested resource
    2284          must be accessed through the proxy given by the Location field. The Location field gave the URI of the proxy. The recipient
    2285          was expected to repeat this single request via the proxy. (<a href="#status.305" id="rfc.xref.status.305.3" title="305 Use Proxy">Section&nbsp;8.3.6</a>)
    2286       </p>
    2287       <p id="rfc.section.A.2.p.5">Reclassify Allow header as response header, removing the option to specify it in a PUT request. Relax the server requirement
    2288          on the contents of the Allow header and remove requirement on clients to always trust the header value. (<a href="#header.allow" id="rfc.xref.header.allow.4" title="Allow">Section&nbsp;9.1</a>)
    2289       </p>
    2290       <p id="rfc.section.A.2.p.6">Correct syntax of Location header to allow URI references (including relative references and fragments), as referred symbol
    2291          "absoluteURI" wasn't what was expected, and add some clarifications as to when use of fragments would not be appropriate.
    2292          (<a href="#header.location" id="rfc.xref.header.location.4" title="Location">Section&nbsp;9.4</a>)
    2293       </p>
    2294       <p id="rfc.section.A.2.p.7">Allow Referer value of "about:blank" as alternative to not specifying it. (<a href="#header.referer" id="rfc.xref.header.referer.3" title="Referer">Section&nbsp;9.6</a>)
    2295       </p>
    2296       <p id="rfc.section.A.2.p.8">In the description of the Server header, the Via field was described as a SHOULD. The requirement was and is stated correctly
    2297          in the description of the Via header in <a href="p1-messaging.html#header.via" title="Via">Section 9.9</a> of <a href="#Part1" id="rfc.xref.Part1.34"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>. (<a href="#header.server" id="rfc.xref.header.server.4" title="Server">Section&nbsp;9.8</a>)
    2298       </p>
    2299       <h1 id="rfc.section.B"><a href="#rfc.section.B">B.</a>&nbsp;<a id="collected.abnf" href="#collected.abnf">Collected ABNF</a></h1>
    2300       <div id="rfc.figure.u.30"></div> <pre class="inline"><a href="#abnf.dependencies" class="smpl">Accept</a> = &lt;Accept, defined in [Part3], Section 5.1&gt;
     2482      <div id="collected.abnf">
     2483         <h1 id="rfc.section.B"><a href="#rfc.section.B">B.</a>&nbsp;<a href="#collected.abnf">Collected ABNF</a></h1>
     2484         <div id="rfc.figure.u.30"></div><pre class="inline"><a href="#abnf.dependencies" class="smpl">Accept</a> = &lt;Accept, defined in [Part3], Section 5.1&gt;
    23012485<a href="#abnf.dependencies" class="smpl">Accept-Charset</a> = &lt;Accept-Charset, defined in [Part3], Section 5.2&gt;
    23022486<a href="#abnf.dependencies" class="smpl">Accept-Encoding</a> = &lt;Accept-Encoding, defined in [Part3], Section 5.3&gt;
    … …  
    24072591
    24082592<a href="#core.rules" class="smpl">token</a> = &lt;token, defined in [Part1], Section 1.2.2&gt;
    2409 </pre> <div id="rfc.figure.u.31"></div>
    2410       <p>ABNF diagnostics:</p><pre class="inline">; Reason-Phrase defined but not used
     2593</pre><div id="rfc.figure.u.31"></div>
     2594         <p>ABNF diagnostics:</p><pre class="inline">; Reason-Phrase defined but not used
    24112595; Status-Code defined but not used
    24122596; request-header defined but not used
    24132597; response-header defined but not used
    2414 </pre><h1 id="rfc.section.C"><a href="#rfc.section.C">C.</a>&nbsp;<a id="change.log" href="#change.log">Change Log (to be removed by RFC Editor before publication)</a></h1>
    2415       <h2 id="rfc.section.C.1"><a href="#rfc.section.C.1">C.1</a>&nbsp;Since RFC2616
    2416       </h2>
    2417       <p id="rfc.section.C.1.p.1">Extracted relevant partitions from <a href="#RFC2616" id="rfc.xref.RFC2616.3"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>.
    2418       </p>
    2419       <h2 id="rfc.section.C.2"><a href="#rfc.section.C.2">C.2</a>&nbsp;Since draft-ietf-httpbis-p2-semantics-00
    2420       </h2>
    2421       <p id="rfc.section.C.2.p.1">Closed issues: </p>
    2422       <ul>
    2423          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/5">http://tools.ietf.org/wg/httpbis/trac/ticket/5</a>&gt;: "Via is a MUST" (&lt;<a href="http://purl.org/NET/http-errata#via-must">http://purl.org/NET/http-errata#via-must</a>&gt;)
    2424          </li>
    2425          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/6">http://tools.ietf.org/wg/httpbis/trac/ticket/6</a>&gt;: "Fragments allowed in Location" (&lt;<a href="http://purl.org/NET/http-errata#location-fragments">http://purl.org/NET/http-errata#location-fragments</a>&gt;)
    2426          </li>
    2427          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/10">http://tools.ietf.org/wg/httpbis/trac/ticket/10</a>&gt;: "Safe Methods vs Redirection" (&lt;<a href="http://purl.org/NET/http-errata#saferedirect">http://purl.org/NET/http-errata#saferedirect</a>&gt;)
    2428          </li>
    2429          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/17">http://tools.ietf.org/wg/httpbis/trac/ticket/17</a>&gt;: "Revise description of the POST method" (&lt;<a href="http://purl.org/NET/http-errata#post">http://purl.org/NET/http-errata#post</a>&gt;)
    2430          </li>
    2431          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/35">http://tools.ietf.org/wg/httpbis/trac/ticket/35</a>&gt;: "Normative and Informative references"
    2432          </li>
    2433          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/42">http://tools.ietf.org/wg/httpbis/trac/ticket/42</a>&gt;: "RFC2606 Compliance"
    2434          </li>
    2435          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/65">http://tools.ietf.org/wg/httpbis/trac/ticket/65</a>&gt;: "Informative references"
    2436          </li>
    2437          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/84">http://tools.ietf.org/wg/httpbis/trac/ticket/84</a>&gt;: "Redundant cross-references"
    2438          </li>
    2439       </ul>
    2440       <p id="rfc.section.C.2.p.2">Other changes: </p>
    2441       <ul>
    2442          <li>Move definitions of 304 and 412 condition codes to <a href="#Part4" id="rfc.xref.Part4.17"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>
    2443          </li>
    2444       </ul>
    2445       <h2 id="rfc.section.C.3"><a href="#rfc.section.C.3">C.3</a>&nbsp;Since draft-ietf-httpbis-p2-semantics-01
    2446       </h2>
    2447       <p id="rfc.section.C.3.p.1">Closed issues: </p>
    2448       <ul>
    2449          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/21">http://tools.ietf.org/wg/httpbis/trac/ticket/21</a>&gt;: "PUT side effects"
    2450          </li>
    2451          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/91">http://tools.ietf.org/wg/httpbis/trac/ticket/91</a>&gt;: "Duplicate Host header requirements"
    2452          </li>
    2453       </ul>
    2454       <p id="rfc.section.C.3.p.2">Ongoing work on ABNF conversion (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/36">http://tools.ietf.org/wg/httpbis/trac/ticket/36</a>&gt;):
    2455       </p>
    2456       <ul>
    2457          <li>Move "Product Tokens" section (back) into Part 1, as "token" is used in the definition of the Upgrade header.</li>
    2458          <li>Add explicit references to BNF syntax and rules imported from other parts of the specification.</li>
    2459          <li>Copy definition of delta-seconds from Part6 instead of referencing it.</li>
    2460       </ul>
    2461       <h2 id="rfc.section.C.4"><a href="#rfc.section.C.4">C.4</a>&nbsp;<a id="changes.since.02" href="#changes.since.02">Since draft-ietf-httpbis-p2-semantics-02</a></h2>
    2462       <p id="rfc.section.C.4.p.1">Closed issues: </p>
    2463       <ul>
    2464          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/24">http://tools.ietf.org/wg/httpbis/trac/ticket/24</a>&gt;: "Requiring Allow in 405 responses"
    2465          </li>
    2466          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/59">http://tools.ietf.org/wg/httpbis/trac/ticket/59</a>&gt;: "Status Code Registry"
    2467          </li>
    2468          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/61">http://tools.ietf.org/wg/httpbis/trac/ticket/61</a>&gt;: "Redirection vs. Location"
    2469          </li>
    2470          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/70">http://tools.ietf.org/wg/httpbis/trac/ticket/70</a>&gt;: "Cacheability of 303 response"
    2471          </li>
    2472          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/76">http://tools.ietf.org/wg/httpbis/trac/ticket/76</a>&gt;: "305 Use Proxy"
    2473          </li>
    2474          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/105">http://tools.ietf.org/wg/httpbis/trac/ticket/105</a>&gt;: "Classification for Allow header"
    2475          </li>
    2476          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/112">http://tools.ietf.org/wg/httpbis/trac/ticket/112</a>&gt;: "PUT - 'store under' vs 'store at'"
    2477          </li>
    2478       </ul>
    2479       <p id="rfc.section.C.4.p.2">Ongoing work on IANA Message Header Registration (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/40">http://tools.ietf.org/wg/httpbis/trac/ticket/40</a>&gt;):
    2480       </p>
    2481       <ul>
    2482          <li>Reference RFC 3984, and update header registrations for headers defined in this document.</li>
    2483       </ul>
    2484       <p id="rfc.section.C.4.p.3">Ongoing work on ABNF conversion (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/36">http://tools.ietf.org/wg/httpbis/trac/ticket/36</a>&gt;):
    2485       </p>
    2486       <ul>
    2487          <li>Replace string literals when the string really is case-sensitive (method).</li>
    2488       </ul>
    2489       <h2 id="rfc.section.C.5"><a href="#rfc.section.C.5">C.5</a>&nbsp;<a id="changes.since.03" href="#changes.since.03">Since draft-ietf-httpbis-p2-semantics-03</a></h2>
    2490       <p id="rfc.section.C.5.p.1">Closed issues: </p>
    2491       <ul>
    2492          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/98">http://tools.ietf.org/wg/httpbis/trac/ticket/98</a>&gt;: "OPTIONS request bodies"
    2493          </li>
    2494          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/119">http://tools.ietf.org/wg/httpbis/trac/ticket/119</a>&gt;: "Description of CONNECT should refer to RFC2817"
    2495          </li>
    2496          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/125">http://tools.ietf.org/wg/httpbis/trac/ticket/125</a>&gt;: "Location Content-Location reference request/response mixup"
    2497          </li>
    2498       </ul>
    2499       <p id="rfc.section.C.5.p.2">Ongoing work on Method Registry (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/72">http://tools.ietf.org/wg/httpbis/trac/ticket/72</a>&gt;):
    2500       </p>
    2501       <ul>
    2502          <li>Added initial proposal for registration process, plus initial content (non-HTTP/1.1 methods to be added by a separate specification).</li>
    2503       </ul>
    2504       <h2 id="rfc.section.C.6"><a href="#rfc.section.C.6">C.6</a>&nbsp;<a id="changes.since.04" href="#changes.since.04">Since draft-ietf-httpbis-p2-semantics-04</a></h2>
    2505       <p id="rfc.section.C.6.p.1">Closed issues: </p>
    2506       <ul>
    2507          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/103">http://tools.ietf.org/wg/httpbis/trac/ticket/103</a>&gt;: "Content-*"
    2508          </li>
    2509          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/132">http://tools.ietf.org/wg/httpbis/trac/ticket/132</a>&gt;: "RFC 2822 is updated by RFC 5322"
    2510          </li>
    2511       </ul>
    2512       <p id="rfc.section.C.6.p.2">Ongoing work on ABNF conversion (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/36">http://tools.ietf.org/wg/httpbis/trac/ticket/36</a>&gt;):
    2513       </p>
    2514       <ul>
    2515          <li>Use "/" instead of "|" for alternatives.</li>
    2516          <li>Introduce new ABNF rules for "bad" whitespace ("BWS"), optional whitespace ("OWS") and required whitespace ("RWS").</li>
    2517          <li>Rewrite ABNFs to spell out whitespace rules, factor out header value format definitions.</li>
    2518       </ul>
    2519       <h2 id="rfc.section.C.7"><a href="#rfc.section.C.7">C.7</a>&nbsp;<a id="changes.since.05" href="#changes.since.05">Since draft-ietf-httpbis-p2-semantics-05</a></h2>
    2520       <p id="rfc.section.C.7.p.1">Closed issues: </p>
    2521       <ul>
    2522          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/94">http://tools.ietf.org/wg/httpbis/trac/ticket/94</a>&gt;: "Reason-Phrase BNF"
    2523          </li>
    2524       </ul>
    2525       <p id="rfc.section.C.7.p.2">Final work on ABNF conversion (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/36">http://tools.ietf.org/wg/httpbis/trac/ticket/36</a>&gt;):
    2526       </p>
    2527       <ul>
    2528          <li>Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.</li>
    2529       </ul>
    2530       <h2 id="rfc.section.C.8"><a href="#rfc.section.C.8">C.8</a>&nbsp;<a id="changes.since.06" href="#changes.since.06">Since draft-ietf-httpbis-p2-semantics-06</a></h2>
    2531       <p id="rfc.section.C.8.p.1">Closed issues: </p>
    2532       <ul>
    2533          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/144">http://tools.ietf.org/wg/httpbis/trac/ticket/144</a>&gt;: "Clarify when Referer is sent"
    2534          </li>
    2535          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/164">http://tools.ietf.org/wg/httpbis/trac/ticket/164</a>&gt;: "status codes vs methods"
    2536          </li>
    2537          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/170">http://tools.ietf.org/wg/httpbis/trac/ticket/170</a>&gt;: "Do not require "updates" relation for specs that register status codes or method names"
    2538          </li>
    2539       </ul>
    2540       <h2 id="rfc.section.C.9"><a href="#rfc.section.C.9">C.9</a>&nbsp;<a id="changes.since.07" href="#changes.since.07">Since draft-ietf-httpbis-p2-semantics-07</a></h2>
    2541       <p id="rfc.section.C.9.p.1">Closed issues: </p>
    2542       <ul>
    2543          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/27">http://tools.ietf.org/wg/httpbis/trac/ticket/27</a>&gt;: "Idempotency"
    2544          </li>
    2545          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/33">http://tools.ietf.org/wg/httpbis/trac/ticket/33</a>&gt;: "TRACE security considerations"
    2546          </li>
    2547          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/110">http://tools.ietf.org/wg/httpbis/trac/ticket/110</a>&gt;: "Clarify rules for determining what entities a response carries"
    2548          </li>
    2549          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/140">http://tools.ietf.org/wg/httpbis/trac/ticket/140</a>&gt;: "update note citing RFC 1945 and 2068"
    2550          </li>
    2551          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/182">http://tools.ietf.org/wg/httpbis/trac/ticket/182</a>&gt;: "update note about redirect limit"
    2552          </li>
    2553          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/191">http://tools.ietf.org/wg/httpbis/trac/ticket/191</a>&gt;: "Location header ABNF should use 'URI'"
    2554          </li>
    2555          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/192">http://tools.ietf.org/wg/httpbis/trac/ticket/192</a>&gt;: "fragments in Location vs status 303"
    2556          </li>
    2557          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/198">http://tools.ietf.org/wg/httpbis/trac/ticket/198</a>&gt;: "move IANA registrations for optional status codes"
    2558          </li>
    2559       </ul>
    2560       <p id="rfc.section.C.9.p.2">Partly resolved issues: </p>
    2561       <ul>
    2562          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/171">http://tools.ietf.org/wg/httpbis/trac/ticket/171</a>&gt;: "Are OPTIONS and TRACE safe?"
    2563          </li>
    2564       </ul>
    2565       <h2 id="rfc.section.C.10"><a href="#rfc.section.C.10">C.10</a>&nbsp;<a id="changes.since.08" href="#changes.since.08">Since draft-ietf-httpbis-p2-semantics-08</a></h2>
    2566       <p id="rfc.section.C.10.p.1">Closed issues: </p>
    2567       <ul>
    2568          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/10">http://tools.ietf.org/wg/httpbis/trac/ticket/10</a>&gt;: "Safe Methods vs Redirection" (we missed the introduction to the 3xx status codes when fixing this previously)
    2569          </li>
    2570       </ul>
    2571       <h2 id="rfc.section.C.11"><a href="#rfc.section.C.11">C.11</a>&nbsp;<a id="changes.since.09" href="#changes.since.09">Since draft-ietf-httpbis-p2-semantics-09</a></h2>
    2572       <p id="rfc.section.C.11.p.1">Closed issues: </p>
    2573       <ul>
    2574          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/43">http://tools.ietf.org/wg/httpbis/trac/ticket/43</a>&gt;: "Fragment combination / precedence during redirects"
    2575          </li>
    2576       </ul>
    2577       <p id="rfc.section.C.11.p.2">Partly resolved issues: </p>
    2578       <ul>
    2579          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/185">http://tools.ietf.org/wg/httpbis/trac/ticket/185</a>&gt;: "Location header payload handling"
    2580          </li>
    2581          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/196">http://tools.ietf.org/wg/httpbis/trac/ticket/196</a>&gt;: "Term for the requested resource's URI"
    2582          </li>
    2583       </ul>
     2598</pre></div>
     2599      <div id="change.log">
     2600         <h1 id="rfc.section.C"><a href="#rfc.section.C">C.</a>&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a></h1>
     2601         <div>
     2602            <h2 id="rfc.section.C.1"><a href="#rfc.section.C.1">C.1</a>&nbsp;Since RFC2616
     2603            </h2>
     2604            <p id="rfc.section.C.1.p.1">Extracted relevant partitions from <a href="#RFC2616" id="rfc.xref.RFC2616.3"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>.
     2605            </p>
     2606         </div>
     2607         <div>
     2608            <h2 id="rfc.section.C.2"><a href="#rfc.section.C.2">C.2</a>&nbsp;Since draft-ietf-httpbis-p2-semantics-00
     2609            </h2>
     2610            <p id="rfc.section.C.2.p.1">Closed issues: </p>
     2611            <ul>
     2612               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/5">http://tools.ietf.org/wg/httpbis/trac/ticket/5</a>&gt;: "Via is a MUST" (&lt;<a href="http://purl.org/NET/http-errata#via-must">http://purl.org/NET/http-errata#via-must</a>&gt;)
     2613               </li>
     2614               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/6">http://tools.ietf.org/wg/httpbis/trac/ticket/6</a>&gt;: "Fragments allowed in Location" (&lt;<a href="http://purl.org/NET/http-errata#location-fragments">http://purl.org/NET/http-errata#location-fragments</a>&gt;)
     2615               </li>
     2616               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/10">http://tools.ietf.org/wg/httpbis/trac/ticket/10</a>&gt;: "Safe Methods vs Redirection" (&lt;<a href="http://purl.org/NET/http-errata#saferedirect">http://purl.org/NET/http-errata#saferedirect</a>&gt;)
     2617               </li>
     2618               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/17">http://tools.ietf.org/wg/httpbis/trac/ticket/17</a>&gt;: "Revise description of the POST method" (&lt;<a href="http://purl.org/NET/http-errata#post">http://purl.org/NET/http-errata#post</a>&gt;)
     2619               </li>
     2620               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/35">http://tools.ietf.org/wg/httpbis/trac/ticket/35</a>&gt;: "Normative and Informative references"
     2621               </li>
     2622               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/42">http://tools.ietf.org/wg/httpbis/trac/ticket/42</a>&gt;: "RFC2606 Compliance"
     2623               </li>
     2624               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/65">http://tools.ietf.org/wg/httpbis/trac/ticket/65</a>&gt;: "Informative references"
     2625               </li>
     2626               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/84">http://tools.ietf.org/wg/httpbis/trac/ticket/84</a>&gt;: "Redundant cross-references"
     2627               </li>
     2628            </ul>
     2629            <p id="rfc.section.C.2.p.2">Other changes: </p>
     2630            <ul>
     2631               <li>Move definitions of 304 and 412 condition codes to <a href="#Part4" id="rfc.xref.Part4.17"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>
     2632               </li>
     2633            </ul>
     2634         </div>
     2635         <div>
     2636            <h2 id="rfc.section.C.3"><a href="#rfc.section.C.3">C.3</a>&nbsp;Since draft-ietf-httpbis-p2-semantics-01
     2637            </h2>
     2638            <p id="rfc.section.C.3.p.1">Closed issues: </p>
     2639            <ul>
     2640               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/21">http://tools.ietf.org/wg/httpbis/trac/ticket/21</a>&gt;: "PUT side effects"
     2641               </li>
     2642               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/91">http://tools.ietf.org/wg/httpbis/trac/ticket/91</a>&gt;: "Duplicate Host header requirements"
     2643               </li>
     2644            </ul>
     2645            <p id="rfc.section.C.3.p.2">Ongoing work on ABNF conversion (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/36">http://tools.ietf.org/wg/httpbis/trac/ticket/36</a>&gt;):
     2646            </p>
     2647            <ul>
     2648               <li>Move "Product Tokens" section (back) into Part 1, as "token" is used in the definition of the Upgrade header.</li>
     2649               <li>Add explicit references to BNF syntax and rules imported from other parts of the specification.</li>
     2650               <li>Copy definition of delta-seconds from Part6 instead of referencing it.</li>
     2651            </ul>
     2652         </div>
     2653         <div id="changes.since.02">
     2654            <h2 id="rfc.section.C.4"><a href="#rfc.section.C.4">C.4</a>&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-p2-semantics-02</a></h2>
     2655            <p id="rfc.section.C.4.p.1">Closed issues: </p>
     2656            <ul>
     2657               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/24">http://tools.ietf.org/wg/httpbis/trac/ticket/24</a>&gt;: "Requiring Allow in 405 responses"
     2658               </li>
     2659               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/59">http://tools.ietf.org/wg/httpbis/trac/ticket/59</a>&gt;: "Status Code Registry"
     2660               </li>
     2661               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/61">http://tools.ietf.org/wg/httpbis/trac/ticket/61</a>&gt;: "Redirection vs. Location"
     2662               </li>
     2663               <li>&lt;<a href="http: