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382</style><link rel="Contents" href="#rfc.toc">
383      <link rel="Author" href="#rfc.authors">
384      <link rel="Copyright" href="#rfc.copyrightnotice">
385      <link rel="Index" href="#rfc.index">
386      <link rel="Chapter" title="1 Introduction" href="#rfc.section.1">
387      <link rel="Chapter" title="2 Protocol Parameters" href="#rfc.section.2">
388      <link rel="Chapter" title="3 Payload" href="#rfc.section.3">
389      <link rel="Chapter" title="4 Representation" href="#rfc.section.4">
390      <link rel="Chapter" title="5 Content Negotiation" href="#rfc.section.5">
391      <link rel="Chapter" title="6 Header Field Definitions" href="#rfc.section.6">
392      <link rel="Chapter" title="7 IANA Considerations" href="#rfc.section.7">
393      <link rel="Chapter" title="8 Security Considerations" href="#rfc.section.8">
394      <link rel="Chapter" title="9 Acknowledgments" href="#rfc.section.9">
395      <link rel="Chapter" href="#rfc.section.10" title="10 References">
396      <link rel="Appendix" title="A Differences between HTTP and MIME" href="#rfc.section.A">
397      <link rel="Appendix" title="B Additional Features" href="#rfc.section.B">
398      <link rel="Appendix" title="C Changes from RFC 2616" href="#rfc.section.C">
399      <link rel="Appendix" title="D Collected ABNF" href="#rfc.section.D">
400      <link rel="Appendix" title="E Change Log (to be removed by RFC Editor before publication)" href="#rfc.section.E">
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402      <link rel="schema.dct" href="http://purl.org/dc/terms/">
403      <meta name="dct.creator" content="Fielding, R.">
404      <meta name="dct.creator" content="Gettys, J.">
405      <meta name="dct.creator" content="Mogul, J.">
406      <meta name="dct.creator" content="Frystyk, H.">
407      <meta name="dct.creator" content="Masinter, L.">
408      <meta name="dct.creator" content="Leach, P.">
409      <meta name="dct.creator" content="Berners-Lee, T.">
410      <meta name="dct.creator" content="Lafon, Y.">
411      <meta name="dct.creator" content="Reschke, J. F.">
412      <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-p3-payload-14">
413      <meta name="dct.issued" scheme="ISO8601" content="2011-04-18">
414      <meta name="dct.replaces" content="urn:ietf:rfc:2616">
415      <meta name="dct.abstract" content="The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. HTTP has been in use by the World Wide Web global information initiative since 1990. This document is Part 3 of the seven-part specification that defines the protocol referred to as &#34;HTTP/1.1&#34; and, taken together, obsoletes RFC 2616. Part 3 defines HTTP message content, metadata, and content negotiation.">
416      <meta name="description" content="The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. HTTP has been in use by the World Wide Web global information initiative since 1990. This document is Part 3 of the seven-part specification that defines the protocol referred to as &#34;HTTP/1.1&#34; and, taken together, obsoletes RFC 2616. Part 3 defines HTTP message content, metadata, and content negotiation.">
417   </head>
418   <body>
419      <table class="header">
420         <tbody>
421            <tr>
422               <td class="left">HTTPbis Working Group</td>
423               <td class="right">R. Fielding, Editor</td>
424            </tr>
425            <tr>
426               <td class="left">Internet-Draft</td>
427               <td class="right">Adobe</td>
428            </tr>
429            <tr>
430               <td class="left">Obsoletes: <a href="https://tools.ietf.org/html/rfc2616">2616</a> (if approved)
431               </td>
432               <td class="right">J. Gettys</td>
433            </tr>
434            <tr>
435               <td class="left">Intended status: Standards Track</td>
436               <td class="right">Alcatel-Lucent</td>
437            </tr>
438            <tr>
439               <td class="left">Expires: October 20, 2011</td>
440               <td class="right">J. Mogul</td>
441            </tr>
442            <tr>
443               <td class="left"></td>
444               <td class="right">HP</td>
445            </tr>
446            <tr>
447               <td class="left"></td>
448               <td class="right">H. Frystyk</td>
449            </tr>
450            <tr>
451               <td class="left"></td>
452               <td class="right">Microsoft</td>
453            </tr>
454            <tr>
455               <td class="left"></td>
456               <td class="right">L. Masinter</td>
457            </tr>
458            <tr>
459               <td class="left"></td>
460               <td class="right">Adobe</td>
461            </tr>
462            <tr>
463               <td class="left"></td>
464               <td class="right">P. Leach</td>
465            </tr>
466            <tr>
467               <td class="left"></td>
468               <td class="right">Microsoft</td>
469            </tr>
470            <tr>
471               <td class="left"></td>
472               <td class="right">T. Berners-Lee</td>
473            </tr>
474            <tr>
475               <td class="left"></td>
476               <td class="right">W3C/MIT</td>
477            </tr>
478            <tr>
479               <td class="left"></td>
480               <td class="right">Y. Lafon, Editor</td>
481            </tr>
482            <tr>
483               <td class="left"></td>
484               <td class="right">W3C</td>
485            </tr>
486            <tr>
487               <td class="left"></td>
488               <td class="right">J. Reschke, Editor</td>
489            </tr>
490            <tr>
491               <td class="left"></td>
492               <td class="right">greenbytes</td>
493            </tr>
494            <tr>
495               <td class="left"></td>
496               <td class="right">April 18, 2011</td>
497            </tr>
498         </tbody>
499      </table>
500      <p class="title">HTTP/1.1, part 3: Message Payload and Content Negotiation<br><span class="filename">draft-ietf-httpbis-p3-payload-14</span></p>
501      <h1 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h1>
502      <p>The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information
503         systems. HTTP has been in use by the World Wide Web global information initiative since 1990. This document is Part 3 of the
504         seven-part specification that defines the protocol referred to as "HTTP/1.1" and, taken together, obsoletes RFC 2616. Part
505         3 defines HTTP message content, metadata, and content negotiation.
506      </p>
507      <h1 id="rfc.note.1"><a href="#rfc.note.1">Editorial Note (To be removed by RFC Editor)</a></h1>
508      <p>Discussion of this draft should take place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org), which is archived
509         at &lt;<a href="http://lists.w3.org/Archives/Public/ietf-http-wg/">http://lists.w3.org/Archives/Public/ietf-http-wg/</a>&gt;.
510      </p>
511      <p>The current issues 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;.
512      </p>
513      <p>The changes in this draft are summarized in <a href="#changes.since.13" title="Since draft-ietf-httpbis-p3-payload-13">Appendix&nbsp;E.15</a>.
514      </p>
515      <div id="rfc.status">
516         <h1><a href="#rfc.status">Status of This Memo</a></h1>
517         <p>This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.</p>
518         <p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute
519            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>.
520         </p>
521         <p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other
522            documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work
523            in progress”.
524         </p>
525         <p>This Internet-Draft will expire on October 20, 2011.</p>
526      </div>
527      <div id="rfc.copyrightnotice">
528         <h1><a href="#rfc.copyrightnotice">Copyright Notice</a></h1>
529         <p>Copyright © 2011 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
530         <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
531            and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License
532            text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified
533            BSD License.
534         </p>
535         <p>This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November
536            10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to
537            allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s)
538            controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative
539            works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate
540            it into languages other than English.
541         </p>
542      </div>
543      <hr class="noprint">
544      <h1 class="np" id="rfc.toc"><a href="#rfc.toc">Table of Contents</a></h1>
545      <ul class="toc">
546         <li><a href="#rfc.section.1">1.</a>&nbsp;&nbsp;&nbsp;<a href="#introduction">Introduction</a><ul>
547               <li><a href="#rfc.section.1.1">1.1</a>&nbsp;&nbsp;&nbsp;<a href="#terminology">Terminology</a></li>
548               <li><a href="#rfc.section.1.2">1.2</a>&nbsp;&nbsp;&nbsp;<a href="#intro.requirements">Requirements</a></li>
549               <li><a href="#rfc.section.1.3">1.3</a>&nbsp;&nbsp;&nbsp;<a href="#notation">Syntax Notation</a><ul>
550                     <li><a href="#rfc.section.1.3.1">1.3.1</a>&nbsp;&nbsp;&nbsp;<a href="#core.rules">Core Rules</a></li>
551                     <li><a href="#rfc.section.1.3.2">1.3.2</a>&nbsp;&nbsp;&nbsp;<a href="#abnf.dependencies">ABNF Rules defined in other Parts of the Specification</a></li>
552                  </ul>
553               </li>
554            </ul>
555         </li>
556         <li><a href="#rfc.section.2">2.</a>&nbsp;&nbsp;&nbsp;<a href="#protocol.parameters">Protocol Parameters</a><ul>
557               <li><a href="#rfc.section.2.1">2.1</a>&nbsp;&nbsp;&nbsp;<a href="#character.sets">Character Encodings (charset)</a></li>
558               <li><a href="#rfc.section.2.2">2.2</a>&nbsp;&nbsp;&nbsp;<a href="#content.codings">Content Codings</a><ul>
559                     <li><a href="#rfc.section.2.2.1">2.2.1</a>&nbsp;&nbsp;&nbsp;<a href="#content.coding.registry">Content Coding Registry</a></li>
560                  </ul>
561               </li>
562               <li><a href="#rfc.section.2.3">2.3</a>&nbsp;&nbsp;&nbsp;<a href="#media.types">Media Types</a><ul>
563                     <li><a href="#rfc.section.2.3.1">2.3.1</a>&nbsp;&nbsp;&nbsp;<a href="#canonicalization.and.text.defaults">Canonicalization and Text Defaults</a></li>
564                     <li><a href="#rfc.section.2.3.2">2.3.2</a>&nbsp;&nbsp;&nbsp;<a href="#multipart.types">Multipart Types</a></li>
565                  </ul>
566               </li>
567               <li><a href="#rfc.section.2.4">2.4</a>&nbsp;&nbsp;&nbsp;<a href="#language.tags">Language Tags</a></li>
568            </ul>
569         </li>
570         <li><a href="#rfc.section.3">3.</a>&nbsp;&nbsp;&nbsp;<a href="#payload">Payload</a><ul>
571               <li><a href="#rfc.section.3.1">3.1</a>&nbsp;&nbsp;&nbsp;<a href="#payload.header.fields">Payload Header Fields</a></li>
572               <li><a href="#rfc.section.3.2">3.2</a>&nbsp;&nbsp;&nbsp;<a href="#payload.body">Payload Body</a></li>
573            </ul>
574         </li>
575         <li><a href="#rfc.section.4">4.</a>&nbsp;&nbsp;&nbsp;<a href="#representation">Representation</a><ul>
576               <li><a href="#rfc.section.4.1">4.1</a>&nbsp;&nbsp;&nbsp;<a href="#representation.header.fields">Representation Header Fields</a></li>
577               <li><a href="#rfc.section.4.2">4.2</a>&nbsp;&nbsp;&nbsp;<a href="#representation.data">Representation Data</a></li>
578            </ul>
579         </li>
580         <li><a href="#rfc.section.5">5.</a>&nbsp;&nbsp;&nbsp;<a href="#content.negotiation">Content Negotiation</a><ul>
581               <li><a href="#rfc.section.5.1">5.1</a>&nbsp;&nbsp;&nbsp;<a href="#server-driven.negotiation">Server-driven Negotiation</a></li>
582               <li><a href="#rfc.section.5.2">5.2</a>&nbsp;&nbsp;&nbsp;<a href="#agent-driven.negotiation">Agent-driven Negotiation</a></li>
583            </ul>
584         </li>
585         <li><a href="#rfc.section.6">6.</a>&nbsp;&nbsp;&nbsp;<a href="#header.fields">Header Field Definitions</a><ul>
586               <li><a href="#rfc.section.6.1">6.1</a>&nbsp;&nbsp;&nbsp;<a href="#header.accept">Accept</a></li>
587               <li><a href="#rfc.section.6.2">6.2</a>&nbsp;&nbsp;&nbsp;<a href="#header.accept-charset">Accept-Charset</a></li>
588               <li><a href="#rfc.section.6.3">6.3</a>&nbsp;&nbsp;&nbsp;<a href="#header.accept-encoding">Accept-Encoding</a></li>
589               <li><a href="#rfc.section.6.4">6.4</a>&nbsp;&nbsp;&nbsp;<a href="#header.accept-language">Accept-Language</a></li>
590               <li><a href="#rfc.section.6.5">6.5</a>&nbsp;&nbsp;&nbsp;<a href="#header.content-encoding">Content-Encoding</a></li>
591               <li><a href="#rfc.section.6.6">6.6</a>&nbsp;&nbsp;&nbsp;<a href="#header.content-language">Content-Language</a></li>
592               <li><a href="#rfc.section.6.7">6.7</a>&nbsp;&nbsp;&nbsp;<a href="#header.content-location">Content-Location</a></li>
593               <li><a href="#rfc.section.6.8">6.8</a>&nbsp;&nbsp;&nbsp;<a href="#header.content-type">Content-Type</a></li>
594            </ul>
595         </li>
596         <li><a href="#rfc.section.7">7.</a>&nbsp;&nbsp;&nbsp;<a href="#IANA.considerations">IANA Considerations</a><ul>
597               <li><a href="#rfc.section.7.1">7.1</a>&nbsp;&nbsp;&nbsp;<a href="#header.field.registration">Header Field Registration</a></li>
598               <li><a href="#rfc.section.7.2">7.2</a>&nbsp;&nbsp;&nbsp;<a href="#content.coding.registration">Content Coding Registry</a></li>
599            </ul>
600         </li>
601         <li><a href="#rfc.section.8">8.</a>&nbsp;&nbsp;&nbsp;<a href="#security.considerations">Security Considerations</a><ul>
602               <li><a href="#rfc.section.8.1">8.1</a>&nbsp;&nbsp;&nbsp;<a href="#privacy.issues.connected.to.accept.header.fields">Privacy Issues Connected to Accept Header Fields</a></li>
603            </ul>
604         </li>
605         <li><a href="#rfc.section.9">9.</a>&nbsp;&nbsp;&nbsp;<a href="#ack">Acknowledgments</a></li>
606         <li><a href="#rfc.section.10">10.</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references">References</a><ul>
607               <li><a href="#rfc.section.10.1">10.1</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.1">Normative References</a></li>
608               <li><a href="#rfc.section.10.2">10.2</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.2">Informative References</a></li>
609            </ul>
610         </li>
611         <li><a href="#rfc.section.A">A.</a>&nbsp;&nbsp;&nbsp;<a href="#differences.between.http.and.mime">Differences between HTTP and MIME</a><ul>
612               <li><a href="#rfc.section.A.1">A.1</a>&nbsp;&nbsp;&nbsp;<a href="#mime-version">MIME-Version</a></li>
613               <li><a href="#rfc.section.A.2">A.2</a>&nbsp;&nbsp;&nbsp;<a href="#conversion.to.canonical.form">Conversion to Canonical Form</a></li>
614               <li><a href="#rfc.section.A.3">A.3</a>&nbsp;&nbsp;&nbsp;<a href="#conversion.of.date.formats">Conversion of Date Formats</a></li>
615               <li><a href="#rfc.section.A.4">A.4</a>&nbsp;&nbsp;&nbsp;<a href="#introduction.of.content-encoding">Introduction of Content-Encoding</a></li>
616               <li><a href="#rfc.section.A.5">A.5</a>&nbsp;&nbsp;&nbsp;<a href="#no.content-transfer-encoding">No Content-Transfer-Encoding</a></li>
617               <li><a href="#rfc.section.A.6">A.6</a>&nbsp;&nbsp;&nbsp;<a href="#introduction.of.transfer-encoding">Introduction of Transfer-Encoding</a></li>
618               <li><a href="#rfc.section.A.7">A.7</a>&nbsp;&nbsp;&nbsp;<a href="#mhtml.line.length">MHTML and Line Length Limitations</a></li>
619            </ul>
620         </li>
621         <li><a href="#rfc.section.B">B.</a>&nbsp;&nbsp;&nbsp;<a href="#additional.features">Additional Features</a></li>
622         <li><a href="#rfc.section.C">C.</a>&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc.2616">Changes from RFC 2616</a></li>
623         <li><a href="#rfc.section.D">D.</a>&nbsp;&nbsp;&nbsp;<a href="#collected.abnf">Collected ABNF</a></li>
624         <li><a href="#rfc.section.E">E.</a>&nbsp;&nbsp;&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a><ul>
625               <li><a href="#rfc.section.E.1">E.1</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.section.E.1">Since RFC 2616</a></li>
626               <li><a href="#rfc.section.E.2">E.2</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.section.E.2">Since draft-ietf-httpbis-p3-payload-00</a></li>
627               <li><a href="#rfc.section.E.3">E.3</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.section.E.3">Since draft-ietf-httpbis-p3-payload-01</a></li>
628               <li><a href="#rfc.section.E.4">E.4</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-p3-payload-02</a></li>
629               <li><a href="#rfc.section.E.5">E.5</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.03">Since draft-ietf-httpbis-p3-payload-03</a></li>
630               <li><a href="#rfc.section.E.6">E.6</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.04">Since draft-ietf-httpbis-p3-payload-04</a></li>
631               <li><a href="#rfc.section.E.7">E.7</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.05">Since draft-ietf-httpbis-p3-payload-05</a></li>
632               <li><a href="#rfc.section.E.8">E.8</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.06">Since draft-ietf-httpbis-p3-payload-06</a></li>
633               <li><a href="#rfc.section.E.9">E.9</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.07">Since draft-ietf-httpbis-p3-payload-07</a></li>
634               <li><a href="#rfc.section.E.10">E.10</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.08">Since draft-ietf-httpbis-p3-payload-08</a></li>
635               <li><a href="#rfc.section.E.11">E.11</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.09">Since draft-ietf-httpbis-p3-payload-09</a></li>
636               <li><a href="#rfc.section.E.12">E.12</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.10">Since draft-ietf-httpbis-p3-payload-10</a></li>
637               <li><a href="#rfc.section.E.13">E.13</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.11">Since draft-ietf-httpbis-p3-payload-11</a></li>
638               <li><a href="#rfc.section.E.14">E.14</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.12">Since draft-ietf-httpbis-p3-payload-12</a></li>
639               <li><a href="#rfc.section.E.15">E.15</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.13">Since draft-ietf-httpbis-p3-payload-13</a></li>
640            </ul>
641         </li>
642         <li><a href="#rfc.index">Index</a></li>
643         <li><a href="#rfc.authors">Authors' Addresses</a></li>
644      </ul>
645      <div id="introduction">
646         <h1 id="rfc.section.1" class="np"><a href="#rfc.section.1">1.</a>&nbsp;<a href="#introduction">Introduction</a></h1>
647         <p id="rfc.section.1.p.1">This document defines HTTP/1.1 message payloads (a.k.a., content), the associated metadata header fields that define how the
648            payload is intended to be interpreted by a recipient, the request header fields that might influence content selection, and
649            the various selection algorithms that are collectively referred to as HTTP content negotiation.
650         </p>
651         <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
652            errata changes. A future draft will reorganize the sections to better reflect the content. In particular, the sections on
653            entities will be renamed payload and moved to the first half of the document, while the sections on content negotiation and
654            associated request header fields will be moved to the second half. The current mess reflects how widely dispersed these topics
655            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>.
656         </p>
657         <div id="terminology">
658            <h2 id="rfc.section.1.1"><a href="#rfc.section.1.1">1.1</a>&nbsp;<a href="#terminology">Terminology</a></h2>
659            <p id="rfc.section.1.1.p.1">This specification uses a number of terms to refer to the roles played by participants in, and objects of, the HTTP communication.</p>
660            <p id="rfc.section.1.1.p.2"><span id="rfc.iref.c.1"></span> <dfn>content negotiation</dfn>
661            </p>
662            <ul class="empty">
663               <li>The mechanism for selecting the appropriate representation when servicing a request. The representation in any response can
664                  be negotiated (including error responses).
665               </li>
666            </ul>
667         </div>
668         <div id="intro.requirements">
669            <h2 id="rfc.section.1.2"><a href="#rfc.section.1.2">1.2</a>&nbsp;<a href="#intro.requirements">Requirements</a></h2>
670            <p id="rfc.section.1.2.p.1">The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
671               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>.
672            </p>
673            <p id="rfc.section.1.2.p.2">An implementation is not compliant if it fails to satisfy one or more of the "MUST" or "REQUIRED" level requirements for the
674               protocols it implements. An implementation that satisfies all the "MUST" or "REQUIRED" level and all the "SHOULD" level requirements
675               for its protocols is said to be "unconditionally compliant"; one that satisfies all the "MUST" level requirements but not
676               all the "SHOULD" level requirements for its protocols is said to be "conditionally compliant".
677            </p>
678         </div>
679         <div id="notation">
680            <h2 id="rfc.section.1.3"><a href="#rfc.section.1.3">1.3</a>&nbsp;<a href="#notation">Syntax Notation</a></h2>
681            <p id="rfc.section.1.3.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.Part1.1"><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;D</a> shows the collected ABNF, with the list rule expanded.
682            </p>
683            <p id="rfc.section.1.3.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
684               (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit sequence of data), SP (space), VCHAR (any visible USASCII character),
685               and WSP (whitespace).
686            </p>
687            <div id="core.rules">
688               <h3 id="rfc.section.1.3.1"><a href="#rfc.section.1.3.1">1.3.1</a>&nbsp;<a href="#core.rules">Core Rules</a></h3>
689               <p id="rfc.section.1.3.1.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.Part1.2"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>:
690               </p>
691               <div id="rfc.figure.u.1"></div><pre class="inline">  <a href="#core.rules" class="smpl">token</a>          = &lt;token, defined in <a href="#Part1" id="rfc.xref.Part1.3"><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;
692  <a href="#core.rules" class="smpl">word</a>           = &lt;word, 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;
693  <a href="#core.rules" class="smpl">OWS</a>            = &lt;OWS, 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;
694</pre></div>
695            <div id="abnf.dependencies">
696               <h3 id="rfc.section.1.3.2"><a href="#rfc.section.1.3.2">1.3.2</a>&nbsp;<a href="#abnf.dependencies">ABNF Rules defined in other Parts of the Specification</a></h3>
697               <p id="rfc.section.1.3.2.p.1">The ABNF rules below are defined in other parts:</p>
698               <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.Part1.6"><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;
699  <a href="#abnf.dependencies" class="smpl">partial-URI</a>    = &lt;partial-URI, 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#uri" title="Uniform Resource Identifiers">Section 2.6</a>&gt;
700  <a href="#abnf.dependencies" class="smpl">qvalue</a>         = &lt;qvalue, 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#quality.values" title="Quality Values">Section 6.4</a>&gt;
701</pre></div>
702         </div>
703      </div>
704      <div id="protocol.parameters">
705         <h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a href="#protocol.parameters">Protocol Parameters</a></h1>
706         <div id="character.sets">
707            <h2 id="rfc.section.2.1"><a href="#rfc.section.2.1">2.1</a>&nbsp;<a href="#character.sets">Character Encodings (charset)</a></h2>
708            <p id="rfc.section.2.1.p.1">HTTP uses charset names to indicate the character encoding of a textual representation.</p>
709            <div id="rule.charset">
710               <p id="rfc.section.2.1.p.2"> A character encoding is identified by a case-insensitive token. The complete set of tokens is defined by the IANA Character
711                  Set registry (&lt;<a href="http://www.iana.org/assignments/character-sets">http://www.iana.org/assignments/character-sets</a>&gt;).
712               </p>
713            </div>
714            <div id="rfc.figure.u.3"></div><pre class="inline"><span id="rfc.iref.g.1"></span>  <a href="#rule.charset" class="smpl">charset</a> = <a href="#core.rules" class="smpl">token</a>
715</pre><p id="rfc.section.2.1.p.4">Although HTTP allows an arbitrary token to be used as a charset value, any token that has a predefined value within the IANA
716               Character Set registry <em class="bcp14">MUST</em> represent the character encoding defined by that registry. Applications <em class="bcp14">SHOULD</em> limit their use of character encodings to those defined within the IANA registry.
717            </p>
718            <p id="rfc.section.2.1.p.5">HTTP uses charset in two contexts: within an Accept-Charset request header field (in which the charset value is an unquoted
719               token) and as the value of a parameter in a Content-Type header field (within a request or response), in which case the parameter
720               value of the charset parameter can be quoted.
721            </p>
722            <p id="rfc.section.2.1.p.6">Implementors need to be aware of IETF character set requirements <a href="#RFC3629" id="rfc.xref.RFC3629.1"><cite title="UTF-8, a transformation format of ISO 10646">[RFC3629]</cite></a> <a href="#RFC2277" id="rfc.xref.RFC2277.1"><cite title="IETF Policy on Character Sets and Languages">[RFC2277]</cite></a>.
723            </p>
724         </div>
725         <div id="content.codings">
726            <h2 id="rfc.section.2.2"><a href="#rfc.section.2.2">2.2</a>&nbsp;<a href="#content.codings">Content Codings</a></h2>
727            <p id="rfc.section.2.2.p.1">Content coding values indicate an encoding transformation that has been or can be applied to a representation. Content codings
728               are primarily used to allow a representation to be compressed or otherwise usefully transformed without losing the identity
729               of its underlying media type and without loss of information. Frequently, the representation is stored in coded form, transmitted
730               directly, and only decoded by the recipient.
731            </p>
732            <div id="rfc.figure.u.4"></div><pre class="inline"><span id="rfc.iref.g.2"></span>  <a href="#content.codings" class="smpl">content-coding</a>   = <a href="#core.rules" class="smpl">token</a>
733</pre><p id="rfc.section.2.2.p.3">All content-coding values are case-insensitive. HTTP/1.1 uses content-coding values in the Accept-Encoding (<a href="#header.accept-encoding" id="rfc.xref.header.accept-encoding.1" title="Accept-Encoding">Section&nbsp;6.3</a>) and Content-Encoding (<a href="#header.content-encoding" id="rfc.xref.header.content-encoding.1" title="Content-Encoding">Section&nbsp;6.5</a>) header fields. Although the value describes the content-coding, what is more important is that it indicates what decoding
734               mechanism will be required to remove the encoding.
735            </p>
736            <p id="rfc.section.2.2.p.4">compress<span id="rfc.iref.c.2"></span><span id="rfc.iref.c.3"></span>
737            </p>
738            <ul class="empty">
739               <li>See <a href="p1-messaging.html#compress.coding" title="Compress Coding">Section 6.2.2.1</a> of <a href="#Part1" id="rfc.xref.Part1.9"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>.
740               </li>
741            </ul>
742            <p id="rfc.section.2.2.p.5">deflate<span id="rfc.iref.d.1"></span><span id="rfc.iref.c.4"></span>
743            </p>
744            <ul class="empty">
745               <li>See <a href="p1-messaging.html#deflate.coding" title="Deflate Coding">Section 6.2.2.2</a> of <a href="#Part1" id="rfc.xref.Part1.10"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>.
746               </li>
747            </ul>
748            <p id="rfc.section.2.2.p.6">gzip<span id="rfc.iref.g.3"></span><span id="rfc.iref.c.5"></span>
749            </p>
750            <ul class="empty">
751               <li>See <a href="p1-messaging.html#gzip.coding" title="Gzip Coding">Section 6.2.2.3</a> of <a href="#Part1" id="rfc.xref.Part1.11"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>.
752               </li>
753            </ul>
754            <p id="rfc.section.2.2.p.7">identity<span id="rfc.iref.i.1"></span><span id="rfc.iref.c.6"></span>
755            </p>
756            <ul class="empty">
757               <li>The default (identity) encoding; the use of no transformation whatsoever. This content-coding is used only in the Accept-Encoding
758                  header field, and <em class="bcp14">SHOULD NOT</em> be used in the Content-Encoding header field.
759               </li>
760            </ul>
761            <div id="content.coding.registry">
762               <h3 id="rfc.section.2.2.1"><a href="#rfc.section.2.2.1">2.2.1</a>&nbsp;<a href="#content.coding.registry">Content Coding Registry</a></h3>
763               <p id="rfc.section.2.2.1.p.1">The HTTP Content Coding Registry defines the name space for the content coding names.</p>
764               <p id="rfc.section.2.2.1.p.2">Registrations <em class="bcp14">MUST</em> include the following fields:
765               </p>
766               <ul>
767                  <li>Name</li>
768                  <li>Description</li>
769                  <li>Pointer to specification text</li>
770               </ul>
771               <p id="rfc.section.2.2.1.p.3">Names of content codings <em class="bcp14">MUST NOT</em> overlap with names of transfer codings (<a href="p1-messaging.html#transfer.codings" title="Transfer Codings">Section 6.2</a> of <a href="#Part1" id="rfc.xref.Part1.12"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>), unless the encoding transformation is identical (as it is the case for the compression codings defined in <a href="p1-messaging.html#compression.codings" title="Compression Codings">Section 6.2.2</a> of <a href="#Part1" id="rfc.xref.Part1.13"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>).
772               </p>
773               <p id="rfc.section.2.2.1.p.4">Values to be added to this name space require a specification (see "Specification Required" in <a href="https://tools.ietf.org/html/rfc5226#section-4.1">Section 4.1</a> of <a href="#RFC5226" id="rfc.xref.RFC5226.1"><cite title="Guidelines for Writing an IANA Considerations Section in RFCs">[RFC5226]</cite></a>), and <em class="bcp14">MUST</em> conform to the purpose of content coding defined in this section.
774               </p>
775               <p id="rfc.section.2.2.1.p.5">The registry itself is maintained at &lt;<a href="http://www.iana.org/assignments/http-parameters">http://www.iana.org/assignments/http-parameters</a>&gt;.
776               </p>
777            </div>
778         </div>
779         <div id="media.types">
780            <h2 id="rfc.section.2.3"><a href="#rfc.section.2.3">2.3</a>&nbsp;<a href="#media.types">Media Types</a></h2>
781            <p id="rfc.section.2.3.p.1">HTTP uses Internet Media Types <a href="#RFC2046" id="rfc.xref.RFC2046.1"><cite title="Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">[RFC2046]</cite></a> in the Content-Type (<a href="#header.content-type" id="rfc.xref.header.content-type.1" title="Content-Type">Section&nbsp;6.8</a>) and Accept (<a href="#header.accept" id="rfc.xref.header.accept.1" title="Accept">Section&nbsp;6.1</a>) header fields in order to provide open and extensible data typing and type negotiation.
782            </p>
783            <div id="rfc.figure.u.5"></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="#media.types" class="smpl">media-type</a> = <a href="#media.types" class="smpl">type</a> "/" <a href="#media.types" class="smpl">subtype</a> *( <a href="#core.rules" class="smpl">OWS</a> ";" <a href="#core.rules" class="smpl">OWS</a> <a href="#rule.parameter" class="smpl">parameter</a> )
784  <a href="#media.types" class="smpl">type</a>       = <a href="#core.rules" class="smpl">token</a>
785  <a href="#media.types" class="smpl">subtype</a>    = <a href="#core.rules" class="smpl">token</a>
786</pre><div id="rule.parameter">
787               <p id="rfc.section.2.3.p.3">   The type/subtype <em class="bcp14">MAY</em> be followed by parameters in the form of attribute/value pairs.
788               </p>
789            </div>
790            <div id="rfc.figure.u.6"></div><pre class="inline"><span id="rfc.iref.g.7"></span><span id="rfc.iref.g.8"></span><span id="rfc.iref.g.9"></span>  <a href="#rule.parameter" class="smpl">parameter</a>      = <a href="#rule.parameter" class="smpl">attribute</a> "=" <a href="#rule.parameter" class="smpl">value</a>
791  <a href="#rule.parameter" class="smpl">attribute</a>      = <a href="#core.rules" class="smpl">token</a>
792  <a href="#rule.parameter" class="smpl">value</a>          = <a href="#core.rules" class="smpl">word</a>
793</pre><p id="rfc.section.2.3.p.5">The type, subtype, and parameter attribute names are case-insensitive. Parameter values might or might not be case-sensitive,
794               depending on the semantics of the parameter name. The presence or absence of a parameter might be significant to the processing
795               of a media-type, depending on its definition within the media type registry.
796            </p>
797            <p id="rfc.section.2.3.p.6">A parameter value that matches the <a href="#core.rules" class="smpl">token</a> production can be transmitted as either a token or within a quoted-string. The quoted and unquoted values are equivalent.
798            </p>
799            <p id="rfc.section.2.3.p.7">Note that some older HTTP applications do not recognize media type parameters. When sending data to older HTTP applications,
800               implementations <em class="bcp14">SHOULD</em> only use media type parameters when they are required by that type/subtype definition.
801            </p>
802            <p id="rfc.section.2.3.p.8">Media-type values are registered with the Internet Assigned Number Authority (IANA). The media type registration process is
803               outlined in <a href="#RFC4288" id="rfc.xref.RFC4288.1"><cite title="Media Type Specifications and Registration Procedures">[RFC4288]</cite></a>. Use of non-registered media types is discouraged.
804            </p>
805            <div id="canonicalization.and.text.defaults">
806               <h3 id="rfc.section.2.3.1"><a href="#rfc.section.2.3.1">2.3.1</a>&nbsp;<a href="#canonicalization.and.text.defaults">Canonicalization and Text Defaults</a></h3>
807               <p id="rfc.section.2.3.1.p.1">Internet media types are registered with a canonical form. A representation transferred via HTTP messages <em class="bcp14">MUST</em> be in the appropriate canonical form prior to its transmission except for "text" types, as defined in the next paragraph.
808               </p>
809               <p id="rfc.section.2.3.1.p.2">When in canonical form, media subtypes of the "text" type use CRLF as the text line break. HTTP relaxes this requirement and
810                  allows the transport of text media with plain CR or LF alone representing a line break when it is done consistently for an
811                  entire representation. HTTP applications <em class="bcp14">MUST</em> accept CRLF, bare CR, and bare LF as indicating a line break in text media received via HTTP. In addition, if the text is
812                  in a character encoding that does not use octets 13 and 10 for CR and LF respectively, as is the case for some multi-byte
813                  character encodings, HTTP allows the use of whatever octet sequences are defined by that character encoding to represent the
814                  equivalent of CR and LF for line breaks. This flexibility regarding line breaks applies only to text media in the payload
815                  body; a bare CR or LF <em class="bcp14">MUST NOT</em> be substituted for CRLF within any of the HTTP control structures (such as header fields and multipart boundaries).
816               </p>
817               <p id="rfc.section.2.3.1.p.3">If a representation is encoded with a content-coding, the underlying data <em class="bcp14">MUST</em> be in a form defined above prior to being encoded.
818               </p>
819            </div>
820            <div id="multipart.types">
821               <h3 id="rfc.section.2.3.2"><a href="#rfc.section.2.3.2">2.3.2</a>&nbsp;<a href="#multipart.types">Multipart Types</a></h3>
822               <p id="rfc.section.2.3.2.p.1">MIME provides for a number of "multipart" types — encapsulations of one or more representations within a single message-body.
823                  All multipart types share a common syntax, as defined in <a href="https://tools.ietf.org/html/rfc2046#section-5.1.1">Section 5.1.1</a> of <a href="#RFC2046" id="rfc.xref.RFC2046.2"><cite title="Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">[RFC2046]</cite></a>, and <em class="bcp14">MUST</em> include a boundary parameter as part of the media type value. The message body is itself a protocol element and <em class="bcp14">MUST</em> therefore use only CRLF to represent line breaks between body-parts.
824               </p>
825               <p id="rfc.section.2.3.2.p.2">In general, HTTP treats a multipart message-body no differently than any other media type: strictly as payload. HTTP does
826                  not use the multipart boundary as an indicator of message-body length.  In all other respects, an HTTP user agent <em class="bcp14">SHOULD</em> follow the same or similar behavior as a MIME user agent would upon receipt of a multipart type. The MIME header fields within
827                  each body-part of a multipart message-body do not have any significance to HTTP beyond that defined by their MIME semantics.
828               </p>
829               <p id="rfc.section.2.3.2.p.3">If an application receives an unrecognized multipart subtype, the application <em class="bcp14">MUST</em> treat it as being equivalent to "multipart/mixed".
830               </p>
831               <div class="note" id="rfc.section.2.3.2.p.4">
832                  <p><b>Note:</b> The "multipart/form-data" type has been specifically defined for carrying form data suitable for processing via the POST request
833                     method, as described in <a href="#RFC2388" id="rfc.xref.RFC2388.1"><cite title="Returning Values from Forms: multipart/form-data">[RFC2388]</cite></a>.
834                  </p>
835               </div>
836            </div>
837         </div>
838         <div id="language.tags">
839            <h2 id="rfc.section.2.4"><a href="#rfc.section.2.4">2.4</a>&nbsp;<a href="#language.tags">Language Tags</a></h2>
840            <p id="rfc.section.2.4.p.1">A language tag, as defined in <a href="#RFC5646" id="rfc.xref.RFC5646.1"><cite title="Tags for Identifying Languages">[RFC5646]</cite></a>, identifies a natural language spoken, written, or otherwise conveyed by human beings for communication of information to
841               other human beings. Computer languages are explicitly excluded. HTTP uses language tags within the Accept-Language and Content-Language
842               fields.
843            </p>
844            <p id="rfc.section.2.4.p.2">In summary, a language tag is composed of one or more parts: A primary language subtag followed by a possibly empty series
845               of subtags:
846            </p>
847            <div id="rfc.figure.u.7"></div><pre class="inline"><span id="rfc.iref.g.10"></span>  <a href="#language.tags" class="smpl">language-tag</a> = &lt;Language-Tag, defined in <a href="#RFC5646" id="rfc.xref.RFC5646.2"><cite title="Tags for Identifying Languages">[RFC5646]</cite></a>, <a href="https://tools.ietf.org/html/rfc5646#section-2.1">Section 2.1</a>&gt;
848</pre><p id="rfc.section.2.4.p.4">White space is not allowed within the tag and all tags are case-insensitive. The name space of language subtags is administered
849               by the IANA (see &lt;<a href="http://www.iana.org/assignments/language-subtag-registry">http://www.iana.org/assignments/language-subtag-registry</a>&gt;).
850            </p>
851            <div id="rfc.figure.u.8"></div>
852            <p>Example tags include:</p><pre class="text">  en, en-US, es-419, az-Arab, x-pig-latin, man-Nkoo-GN
853</pre><p id="rfc.section.2.4.p.6">See <a href="#RFC5646" id="rfc.xref.RFC5646.3"><cite title="Tags for Identifying Languages">[RFC5646]</cite></a> for further information.
854            </p>
855         </div>
856      </div>
857      <div id="payload">
858         <h1 id="rfc.section.3"><a href="#rfc.section.3">3.</a>&nbsp;<a href="#payload">Payload</a></h1>
859         <p id="rfc.section.3.p.1">HTTP messages <em class="bcp14">MAY</em> transfer a payload if not otherwise restricted by the request method or response status code. The payload consists of metadata,
860            in the form of header fields, and data, in the form of the sequence of octets in the message-body after any transfer-coding
861            has been decoded.
862         </p>
863         <div id="rfc.iref.p.1"></div>
864         <p id="rfc.section.3.p.2">A "<dfn>payload</dfn>" in HTTP is always a partial or complete representation of some resource. We use separate terms for payload and representation
865            because some messages contain only the associated representation's header fields (e.g., responses to HEAD) or only some part(s)
866            of the representation (e.g., the 206 status code).
867         </p>
868         <div id="payload.header.fields">
869            <h2 id="rfc.section.3.1"><a href="#rfc.section.3.1">3.1</a>&nbsp;<a href="#payload.header.fields">Payload Header Fields</a></h2>
870            <p id="rfc.section.3.1.p.1">HTTP header fields that specifically define the payload, rather than the associated representation, are referred to as "payload
871               header fields". The following payload header fields are defined by HTTP/1.1:
872            </p>
873            <div id="rfc.table.u.1">
874               <table class="tt full left" cellpadding="3" cellspacing="0">
875                  <thead>
876                     <tr>
877                        <th>Header Field Name</th>
878                        <th>Defined in...</th>
879                     </tr>
880                  </thead>
881                  <tbody>
882                     <tr>
883                        <td class="left">Content-Length</td>
884                        <td class="left"><a href="p1-messaging.html#header.content-length" title="Content-Length">Section 9.2</a> of <a href="#Part1" id="rfc.xref.Part1.14"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a></td>
885                     </tr>
886                     <tr>
887                        <td class="left">Content-Range</td>
888                        <td class="left"><a href="p5-range.html#header.content-range" title="Content-Range">Section 5.2</a> of <a href="#Part5" id="rfc.xref.Part5.1"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a></td>
889                     </tr>
890                  </tbody>
891               </table>
892            </div>
893         </div>
894         <div id="payload.body">
895            <h2 id="rfc.section.3.2"><a href="#rfc.section.3.2">3.2</a>&nbsp;<a href="#payload.body">Payload Body</a></h2>
896            <p id="rfc.section.3.2.p.1">A payload 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.Part1.15"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>. The payload body is obtained from the message-body by decoding any Transfer-Encoding that might have been applied to ensure
897               safe and proper transfer of the message.
898            </p>
899         </div>
900      </div>
901      <div id="representation">
902         <div id="rfc.iref.r.1"></div>
903         <h1 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a href="#representation">Representation</a></h1>
904         <p id="rfc.section.4.p.1">A "<dfn>representation</dfn>" is information in a format that can be readily communicated from one party to another. A resource representation is information
905            that reflects the state of that resource, as observed at some point in the past (e.g., in a response to GET) or to be desired
906            at some point in the future (e.g., in a PUT request).
907         </p>
908         <p id="rfc.section.4.p.2">Most, but not all, representations transferred via HTTP are intended to be a representation of the target resource (the resource
909            identified by the effective request URI). The precise semantics of a representation are determined by the type of message
910            (request or response), the request method, the response status code, and the representation metadata. For example, the above
911            semantic is true for the representation in any 200 (OK) response to GET and for the representation in any PUT request. A 200
912            response to PUT, in contrast, contains either a representation that describes the successful action or a representation of
913            the target resource, with the latter indicated by a Content-Location header field with the same value as the effective request
914            URI. Likewise, response messages with an error status code usually contain a representation that describes the error and what
915            next steps are suggested for resolving it.
916         </p>
917         <div id="representation.header.fields">
918            <h2 id="rfc.section.4.1"><a href="#rfc.section.4.1">4.1</a>&nbsp;<a href="#representation.header.fields">Representation Header Fields</a></h2>
919            <p id="rfc.section.4.1.p.1">Representation header fields define metadata about the representation data enclosed in the message-body or, if no message-body
920               is present, about the representation that would have been transferred in a 200 response to a simultaneous GET request with
921               the same effective request URI.
922            </p>
923            <p id="rfc.section.4.1.p.2">The following header fields are defined as representation metadata:</p>
924            <div id="rfc.table.u.2">
925               <table class="tt full left" cellpadding="3" cellspacing="0">
926                  <thead>
927                     <tr>
928                        <th>Header Field Name</th>
929                        <th>Defined in...</th>
930                     </tr>
931                  </thead>
932                  <tbody>
933                     <tr>
934                        <td class="left">Content-Encoding</td>
935                        <td class="left"><a href="#header.content-encoding" id="rfc.xref.header.content-encoding.2" title="Content-Encoding">Section&nbsp;6.5</a></td>
936                     </tr>
937                     <tr>
938                        <td class="left">Content-Language</td>
939                        <td class="left"><a href="#header.content-language" id="rfc.xref.header.content-language.1" title="Content-Language">Section&nbsp;6.6</a></td>
940                     </tr>
941                     <tr>
942                        <td class="left">Content-Location</td>
943                        <td class="left"><a href="#header.content-location" id="rfc.xref.header.content-location.1" title="Content-Location">Section&nbsp;6.7</a></td>
944                     </tr>
945                     <tr>
946                        <td class="left">Content-Type</td>
947                        <td class="left"><a href="#header.content-type" id="rfc.xref.header.content-type.2" title="Content-Type">Section&nbsp;6.8</a></td>
948                     </tr>
949                     <tr>
950                        <td class="left">Expires</td>
951                        <td class="left"><a href="p6-cache.html#header.expires" title="Expires">Section 3.3</a> of <a href="#Part6" id="rfc.xref.Part6.1"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a></td>
952                     </tr>
953                     <tr>
954                        <td class="left">Last-Modified</td>
955                        <td class="left"><a href="p4-conditional.html#header.last-modified" title="Last-Modified">Section 2.1</a> of <a href="#Part4" id="rfc.xref.Part4.1"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a></td>
956                     </tr>
957                  </tbody>
958               </table>
959            </div>
960         </div>
961         <div id="representation.data">
962            <h2 id="rfc.section.4.2"><a href="#rfc.section.4.2">4.2</a>&nbsp;<a href="#representation.data">Representation Data</a></h2>
963            <p id="rfc.section.4.2.p.1">The representation body associated with an HTTP message is either provided as the payload body of the message or referred
964               to by the message semantics and the effective request URI. The representation data is in a format and encoding defined by
965               the representation metadata header fields.
966            </p>
967            <p id="rfc.section.4.2.p.2">The data type of the representation data is determined via the header fields Content-Type and Content-Encoding. These define
968               a two-layer, ordered encoding model:
969            </p>
970            <div id="rfc.figure.u.9"></div><pre class="text">  representation-data := Content-Encoding( Content-Type( bits ) )
971</pre><p id="rfc.section.4.2.p.4">Content-Type specifies the media type of the underlying data, which defines both the data format and how that data <em class="bcp14">SHOULD</em> be processed by the recipient (within the scope of the request method semantics). Any HTTP/1.1 message containing a payload
972               body <em class="bcp14">SHOULD</em> include a Content-Type header field defining the media type of the associated representation unless that metadata is unknown
973               to the sender. If the Content-Type header field is not present, it indicates that the sender does not know the media type
974               of the representation; recipients <em class="bcp14">MAY</em> either assume that the media type is "application/octet-stream" (<a href="#RFC2046" id="rfc.xref.RFC2046.3"><cite title="Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">[RFC2046]</cite></a>, <a href="https://tools.ietf.org/html/rfc2046#section-4.5.1">Section 4.5.1</a>) or examine the content to determine its type.
975            </p>
976            <p id="rfc.section.4.2.p.5">In practice, resource owners do not always properly configure their origin server to provide the correct Content-Type for
977               a given representation, with the result that some clients will examine a response body's content and override the specified
978               type. Clients that do so risk drawing incorrect conclusions, which might expose additional security risks (e.g., "privilege
979               escalation"). Furthermore, it is impossible to determine the sender's intent by examining the data format: many data formats
980               match multiple media types that differ only in processing semantics. Implementers are encouraged to provide a means of disabling
981               such "content sniffing" when it is used.
982            </p>
983            <p id="rfc.section.4.2.p.6">Content-Encoding is used to indicate any additional content codings applied to the data, usually for the purpose of data compression,
984               that are a property of the representation. If Content-Encoding is not present, then there is no additional encoding beyond
985               that defined by the Content-Type.
986            </p>
987         </div>
988      </div>
989      <div id="content.negotiation">
990         <h1 id="rfc.section.5"><a href="#rfc.section.5">5.</a>&nbsp;<a href="#content.negotiation">Content Negotiation</a></h1>
991         <p id="rfc.section.5.p.1">HTTP responses include a representation which contains information for interpretation, whether by a human user or for further
992            processing. Often, the server has different ways of representing the same information; for example, in different formats,
993            languages, or using different character encodings.
994         </p>
995         <p id="rfc.section.5.p.2">HTTP clients and their users might have different or variable capabilities, characteristics or preferences which would influence
996            which representation, among those available from the server, would be best for the server to deliver. For this reason, HTTP
997            provides mechanisms for "content negotiation" — a process of allowing selection of a representation of a given resource, when
998            more than one is available.
999         </p>
1000         <p id="rfc.section.5.p.3">This specification defines two patterns of content negotiation; "server-driven", where the server selects the representation
1001            based upon the client's stated preferences, and "agent-driven" negotiation, where the server provides a list of representations
1002            for the client to choose from, based upon their metadata. In addition, there are other patterns: some applications use an
1003            "active content" pattern, where the server returns active content which runs on the client and, based on client available
1004            parameters, selects additional resources to invoke. "Transparent Content Negotiation" (<a href="#RFC2295" id="rfc.xref.RFC2295.1"><cite title="Transparent Content Negotiation in HTTP">[RFC2295]</cite></a>) has also been proposed.
1005         </p>
1006         <p id="rfc.section.5.p.4">These patterns are all widely used, and have trade-offs in applicability and practicality. In particular, when the number
1007            of preferences or capabilities to be expressed by a client are large (such as when many different formats are supported by
1008            a user-agent), server-driven negotiation becomes unwieldy, and might not be appropriate. Conversely, when the number of representations
1009            to choose from is very large, agent-driven negotiation might not be appropriate.
1010         </p>
1011         <p id="rfc.section.5.p.5">Note that in all cases, the supplier of representations has the responsibility for determining which representations might
1012            be considered to be the "same information".
1013         </p>
1014         <div id="server-driven.negotiation">
1015            <h2 id="rfc.section.5.1"><a href="#rfc.section.5.1">5.1</a>&nbsp;<a href="#server-driven.negotiation">Server-driven Negotiation</a></h2>
1016            <p id="rfc.section.5.1.p.1">If the selection of the best representation for a response is made by an algorithm located at the server, it is called server-driven
1017               negotiation. Selection is based on the available representations of the response (the dimensions over which it can vary; e.g.,
1018               language, content-coding, etc.) and the contents of particular header fields in the request message or on other information
1019               pertaining to the request (such as the network address of the client).
1020            </p>
1021            <p id="rfc.section.5.1.p.2">Server-driven negotiation is advantageous when the algorithm for selecting from among the available representations is difficult
1022               to describe to the user agent, or when the server desires to send its "best guess" to the client along with the first response
1023               (hoping to avoid the round-trip delay of a subsequent request if the "best guess" is good enough for the user). In order to
1024               improve the server's guess, the user agent <em class="bcp14">MAY</em> include request header fields (Accept, Accept-Language, Accept-Encoding, etc.) which describe its preferences for such a response.
1025            </p>
1026            <p id="rfc.section.5.1.p.3">Server-driven negotiation has disadvantages: </p>
1027            <ol>
1028               <li>It is impossible for the server to accurately determine what might be "best" for any given user, since that would require
1029                  complete knowledge of both the capabilities of the user agent and the intended use for the response (e.g., does the user want
1030                  to view it on screen or print it on paper?).
1031               </li>
1032               <li>Having the user agent describe its capabilities in every request can be both very inefficient (given that only a small percentage
1033                  of responses have multiple representations) and a potential violation of the user's privacy.
1034               </li>
1035               <li>It complicates the implementation of an origin server and the algorithms for generating responses to a request.</li>
1036               <li>It might limit a public cache's ability to use the same response for multiple user's requests.</li>
1037            </ol>
1038            <p id="rfc.section.5.1.p.4">HTTP/1.1 includes the following header fields for enabling server-driven negotiation through description of user agent capabilities
1039               and user preferences: Accept (<a href="#header.accept" id="rfc.xref.header.accept.2" title="Accept">Section&nbsp;6.1</a>), Accept-Charset (<a href="#header.accept-charset" id="rfc.xref.header.accept-charset.1" title="Accept-Charset">Section&nbsp;6.2</a>), Accept-Encoding (<a href="#header.accept-encoding" id="rfc.xref.header.accept-encoding.2" title="Accept-Encoding">Section&nbsp;6.3</a>), Accept-Language (<a href="#header.accept-language" id="rfc.xref.header.accept-language.1" title="Accept-Language">Section&nbsp;6.4</a>), and User-Agent (<a href="p2-semantics.html#header.user-agent" title="User-Agent">Section 9.9</a> of <a href="#Part2" id="rfc.xref.Part2.1"><cite title="HTTP/1.1, part 2: Message Semantics">[Part2]</cite></a>). However, an origin server is not limited to these dimensions and <em class="bcp14">MAY</em> vary the response based on any aspect of the request, including aspects of the connection (e.g., IP address) or information
1040               within extension header fields not defined by this specification.
1041            </p>
1042            <div class="note" id="rfc.section.5.1.p.5">
1043               <p><b>Note:</b> In practice, User-Agent based negotiation is fragile, because new clients might not be recognized.
1044               </p>
1045            </div>
1046            <p id="rfc.section.5.1.p.6">The Vary header field (<a href="p6-cache.html#header.vary" title="Vary">Section 3.5</a> of <a href="#Part6" id="rfc.xref.Part6.2"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a>) can be used to express the parameters the server uses to select a representation that is subject to server-driven negotiation.
1047            </p>
1048         </div>
1049         <div id="agent-driven.negotiation">
1050            <h2 id="rfc.section.5.2"><a href="#rfc.section.5.2">5.2</a>&nbsp;<a href="#agent-driven.negotiation">Agent-driven Negotiation</a></h2>
1051            <p id="rfc.section.5.2.p.1">With agent-driven negotiation, selection of the best representation for a response is performed by the user agent after receiving
1052               an initial response from the origin server. Selection is based on a list of the available representations of the response
1053               included within the header fields or body of the initial response, with each representation identified by its own URI. Selection
1054               from among the representations can be performed automatically (if the user agent is capable of doing so) or manually by the
1055               user selecting from a generated (possibly hypertext) menu.
1056            </p>
1057            <p id="rfc.section.5.2.p.2">Agent-driven negotiation is advantageous when the response would vary over commonly-used dimensions (such as type, language,
1058               or encoding), when the origin server is unable to determine a user agent's capabilities from examining the request, and generally
1059               when public caches are used to distribute server load and reduce network usage.
1060            </p>
1061            <p id="rfc.section.5.2.p.3">Agent-driven negotiation suffers from the disadvantage of needing a second request to obtain the best alternate representation.
1062               This second request is only efficient when caching is used. In addition, this specification does not define any mechanism
1063               for supporting automatic selection, though it also does not prevent any such mechanism from being developed as an extension
1064               and used within HTTP/1.1.
1065            </p>
1066            <p id="rfc.section.5.2.p.4">This specification defines the 300 (Multiple Choices) and 406 (Not Acceptable) status codes for enabling agent-driven negotiation
1067               when the server is unwilling or unable to provide a varying response using server-driven negotiation.
1068            </p>
1069         </div>
1070      </div>
1071      <div id="header.fields">
1072         <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a href="#header.fields">Header Field Definitions</a></h1>
1073         <p id="rfc.section.6.p.1">This section defines the syntax and semantics of HTTP/1.1 header fields related to the payload of messages.</p>
1074         <div id="header.accept">
1075            <div id="rfc.iref.a.1"></div>
1076            <div id="rfc.iref.h.1"></div>
1077            <h2 id="rfc.section.6.1"><a href="#rfc.section.6.1">6.1</a>&nbsp;<a href="#header.accept">Accept</a></h2>
1078            <p id="rfc.section.6.1.p.1">The "Accept" header field can be used by user agents to specify response media types that are acceptable. Accept header fields
1079               can be used to indicate that the request is specifically limited to a small set of desired types, as in the case of a request
1080               for an in-line image.
1081            </p>
1082            <div id="rfc.figure.u.10"></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>  <a href="#header.accept" class="smpl">Accept</a> = #( <a href="#header.accept" class="smpl">media-range</a> [ <a href="#header.accept" class="smpl">accept-params</a> ] )
1083 
1084  <a href="#header.accept" class="smpl">media-range</a>    = ( "*/*"
1085                   / ( <a href="#media.types" class="smpl">type</a> "/" "*" )
1086                   / ( <a href="#media.types" class="smpl">type</a> "/" <a href="#media.types" class="smpl">subtype</a> )
1087                   ) *( <a href="#core.rules" class="smpl">OWS</a> ";" <a href="#core.rules" class="smpl">OWS</a> <a href="#rule.parameter" class="smpl">parameter</a> )
1088  <a href="#header.accept" class="smpl">accept-params</a>  = <a href="#core.rules" class="smpl">OWS</a> ";" <a href="#core.rules" class="smpl">OWS</a> "q=" <a href="#abnf.dependencies" class="smpl">qvalue</a> *( <a href="#header.accept" class="smpl">accept-ext</a> )
1089  <a href="#header.accept" class="smpl">accept-ext</a>     = <a href="#core.rules" class="smpl">OWS</a> ";" <a href="#core.rules" class="smpl">OWS</a> <a href="#core.rules" class="smpl">token</a> [ "=" <a href="#core.rules" class="smpl">word</a> ]
1090</pre><p id="rfc.section.6.1.p.3">The asterisk "*" character is used to group media types into ranges, with "*/*" indicating all media types and "type/*" indicating
1091               all subtypes of that type. The media-range <em class="bcp14">MAY</em> include media type parameters that are applicable to that range.
1092            </p>
1093            <p id="rfc.section.6.1.p.4">Each media-range <em class="bcp14">MAY</em> be followed by one or more accept-params, beginning with the "q" parameter for indicating a relative quality factor. The first
1094               "q" parameter (if any) separates the media-range parameter(s) from the accept-params. Quality factors allow the user or user
1095               agent to indicate the relative degree of preference for that media-range, using the qvalue scale from 0 to 1 (<a href="p1-messaging.html#quality.values" title="Quality Values">Section 6.4</a> of <a href="#Part1" id="rfc.xref.Part1.16"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). The default value is q=1.
1096            </p>
1097            <div class="note" id="rfc.section.6.1.p.5">
1098               <p><b>Note:</b> Use of the "q" parameter name to separate media type parameters from Accept extension parameters is due to historical practice.
1099                  Although this prevents any media type parameter named "q" from being used with a media range, such an event is believed to
1100                  be unlikely given the lack of any "q" parameters in the IANA media type registry and the rare usage of any media type parameters
1101                  in Accept. Future media types are discouraged from registering any parameter named "q".
1102               </p>
1103            </div>
1104            <p id="rfc.section.6.1.p.6">The example</p>
1105            <div id="rfc.figure.u.11"></div><pre class="text">  Accept: audio/*; q=0.2, audio/basic
1106</pre><p id="rfc.section.6.1.p.8"><em class="bcp14">SHOULD</em> be interpreted as "I prefer audio/basic, but send me any audio type if it is the best available after an 80% mark-down in
1107               quality".
1108            </p>
1109            <p id="rfc.section.6.1.p.9">If no Accept header field is present, then it is assumed that the client accepts all media types. If an Accept header field
1110               is present, and if the server cannot send a response which is acceptable according to the combined Accept field value, then
1111               the server <em class="bcp14">SHOULD</em> send a 406 (Not Acceptable) response.
1112            </p>
1113            <p id="rfc.section.6.1.p.10">A more elaborate example is</p>
1114            <div id="rfc.figure.u.12"></div><pre class="text">  Accept: text/plain; q=0.5, text/html,
1115          text/x-dvi; q=0.8, text/x-c
1116</pre><p id="rfc.section.6.1.p.12">Verbally, this would be interpreted as "text/html and text/x-c are the preferred media types, but if they do not exist, then
1117               send the text/x-dvi representation, and if that does not exist, send the text/plain representation".
1118            </p>
1119            <p id="rfc.section.6.1.p.13">Media ranges can be overridden by more specific media ranges or specific media types. If more than one media range applies
1120               to a given type, the most specific reference has precedence. For example,
1121            </p>
1122            <div id="rfc.figure.u.13"></div><pre class="text">  Accept: text/*, text/plain, text/plain;format=flowed, */*
1123</pre><p id="rfc.section.6.1.p.15">have the following precedence: </p>
1124            <ol>
1125               <li>text/plain;format=flowed</li>
1126               <li>text/plain</li>
1127               <li>text/*</li>
1128               <li>*/*</li>
1129            </ol>
1130            <p id="rfc.section.6.1.p.16">The media type quality factor associated with a given type is determined by finding the media range with the highest precedence
1131               which matches that type. For example,
1132            </p>
1133            <div id="rfc.figure.u.14"></div><pre class="text">  Accept: text/*;q=0.3, text/html;q=0.7, text/html;level=1,
1134          text/html;level=2;q=0.4, */*;q=0.5
1135</pre><p id="rfc.section.6.1.p.18">would cause the following values to be associated:</p>
1136            <div id="rfc.table.u.3">
1137               <table class="tt full left" cellpadding="3" cellspacing="0">
1138                  <thead>
1139                     <tr>
1140                        <th>Media Type</th>
1141                        <th>Quality Value</th>
1142                     </tr>
1143                  </thead>
1144                  <tbody>
1145                     <tr>
1146                        <td class="left">text/html;level=1</td>
1147                        <td class="left">1</td>
1148                     </tr>
1149                     <tr>
1150                        <td class="left">text/html</td>
1151                        <td class="left">0.7</td>
1152                     </tr>
1153                     <tr>
1154                        <td class="left">text/plain</td>
1155                        <td class="left">0.3</td>
1156                     </tr>
1157                     <tr>
1158                        <td class="left">image/jpeg</td>
1159                        <td class="left">0.5</td>
1160                     </tr>
1161                     <tr>
1162                        <td class="left">text/html;level=2</td>
1163                        <td class="left">0.4</td>
1164                     </tr>
1165                     <tr>
1166                        <td class="left">text/html;level=3</td>
1167                        <td class="left">0.7</td>
1168                     </tr>
1169                  </tbody>
1170               </table>
1171            </div>
1172            <p id="rfc.section.6.1.p.19"><b>Note:</b> A user agent might be provided with a default set of quality values for certain media ranges. However, unless the user agent
1173               is a closed system which cannot interact with other rendering agents, this default set ought to be configurable by the user.
1174            </p>
1175         </div>
1176         <div id="header.accept-charset">
1177            <div id="rfc.iref.a.2"></div>
1178            <div id="rfc.iref.h.2"></div>
1179            <h2 id="rfc.section.6.2"><a href="#rfc.section.6.2">6.2</a>&nbsp;<a href="#header.accept-charset">Accept-Charset</a></h2>
1180            <p id="rfc.section.6.2.p.1">The "Accept-Charset" header field can be used by user agents to indicate what character encodings are acceptable in a response
1181               payload. This field allows clients capable of understanding more comprehensive or special-purpose character encodings to signal
1182               that capability to a server which is capable of representing documents in those character encodings.
1183            </p>
1184            <div id="rfc.figure.u.15"></div><pre class="inline"><span id="rfc.iref.g.15"></span>  <a href="#header.accept-charset" class="smpl">Accept-Charset</a> = 1#( ( <a href="#rule.charset" class="smpl">charset</a> / "*" )
1185                         [ <a href="#core.rules" class="smpl">OWS</a> ";" <a href="#core.rules" class="smpl">OWS</a> "q=" <a href="#abnf.dependencies" class="smpl">qvalue</a> ] )
1186</pre><p id="rfc.section.6.2.p.3">Character encoding values (a.k.a., charsets) are described in <a href="#character.sets" title="Character Encodings (charset)">Section&nbsp;2.1</a>. Each charset <em class="bcp14">MAY</em> be given an associated quality value which represents the user's preference for that charset. The default value is q=1. An
1187               example is
1188            </p>
1189            <div id="rfc.figure.u.16"></div><pre class="text">  Accept-Charset: iso-8859-5, unicode-1-1;q=0.8
1190</pre><p id="rfc.section.6.2.p.5">The special value "*", if present in the Accept-Charset field, matches every character encoding which is not mentioned elsewhere
1191               in the Accept-Charset field. If no "*" is present in an Accept-Charset field, then all character encodings not explicitly
1192               mentioned get a quality value of 0.
1193            </p>
1194            <p id="rfc.section.6.2.p.6">If no Accept-Charset header field is present, the default is that any character encoding is acceptable. If an Accept-Charset
1195               header field is present, and if the server cannot send a response which is acceptable according to the Accept-Charset header
1196               field, then the server <em class="bcp14">SHOULD</em> send an error response with the 406 (Not Acceptable) status code, though the sending of an unacceptable response is also allowed.
1197            </p>
1198         </div>
1199         <div id="header.accept-encoding">
1200            <div id="rfc.iref.a.3"></div>
1201            <div id="rfc.iref.h.3"></div>
1202            <h2 id="rfc.section.6.3"><a href="#rfc.section.6.3">6.3</a>&nbsp;<a href="#header.accept-encoding">Accept-Encoding</a></h2>
1203            <p id="rfc.section.6.3.p.1">The "Accept-Encoding" header field can be used by user agents to indicate what response content-codings (<a href="#content.codings" title="Content Codings">Section&nbsp;2.2</a>) are acceptable in the response.
1204            </p>
1205            <div id="rfc.figure.u.17"></div><pre class="inline"><span id="rfc.iref.g.16"></span><span id="rfc.iref.g.17"></span>  <a href="#header.accept-encoding" class="smpl">Accept-Encoding</a>  = #( <a href="#header.accept-encoding" class="smpl">codings</a> [ <a href="#core.rules" class="smpl">OWS</a> ";" <a href="#core.rules" class="smpl">OWS</a> "q=" <a href="#abnf.dependencies" class="smpl">qvalue</a> ] )
1206  <a href="#header.accept-encoding" class="smpl">codings</a>          = ( <a href="#content.codings" class="smpl">content-coding</a> / "*" )
1207</pre><p id="rfc.section.6.3.p.3">Each codings value <em class="bcp14">MAY</em> be given an associated quality value which represents the preference for that encoding. The default value is q=1.
1208            </p>
1209            <p id="rfc.section.6.3.p.4">Examples of its use are:</p>
1210            <div id="rfc.figure.u.18"></div><pre class="text">  Accept-Encoding: compress, gzip
1211  Accept-Encoding:
1212  Accept-Encoding: *
1213  Accept-Encoding: compress;q=0.5, gzip;q=1.0
1214  Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0
1215</pre><p id="rfc.section.6.3.p.6">A server tests whether a content-coding is acceptable, according to an Accept-Encoding field, using these rules: </p>
1216            <ol>
1217               <li>If the content-coding is one of the content-codings listed in the Accept-Encoding field, then it is acceptable, unless it
1218                  is accompanied by a qvalue of 0. (As defined in <a href="p1-messaging.html#quality.values" title="Quality Values">Section 6.4</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>, a qvalue of 0 means "not acceptable".)
1219               </li>
1220               <li>The special "*" symbol in an Accept-Encoding field matches any available content-coding not explicitly listed in the header
1221                  field.
1222               </li>
1223               <li>If multiple content-codings are acceptable, then the acceptable content-coding with the highest non-zero qvalue is preferred.</li>
1224               <li>The "identity" content-coding is always acceptable, unless specifically refused because the Accept-Encoding field includes
1225                  "identity;q=0", or because the field includes "*;q=0" and does not explicitly include the "identity" content-coding. If the
1226                  Accept-Encoding field-value is empty, then only the "identity" encoding is acceptable.
1227               </li>
1228            </ol>
1229            <p id="rfc.section.6.3.p.7">If an Accept-Encoding field is present in a request, and if the server cannot send a response which is acceptable according
1230               to the Accept-Encoding header field, then the server <em class="bcp14">SHOULD</em> send an error response with the 406 (Not Acceptable) status code.
1231            </p>
1232            <p id="rfc.section.6.3.p.8">If no Accept-Encoding field is present in a request, the server <em class="bcp14">MAY</em> assume that the client will accept any content coding. In this case, if "identity" is one of the available content-codings,
1233               then the server <em class="bcp14">SHOULD</em> use the "identity" content-coding, unless it has additional information that a different content-coding is meaningful to the
1234               client.
1235            </p>
1236            <div class="note" id="rfc.section.6.3.p.9">
1237               <p><b>Note:</b> If the request does not include an Accept-Encoding field, and if the "identity" content-coding is unavailable, then content-codings
1238                  commonly understood by HTTP/1.0 clients (i.e., "gzip" and "compress") are preferred; some older clients improperly display
1239                  messages sent with other content-codings. The server might also make this decision based on information about the particular
1240                  user-agent or client.
1241               </p>
1242            </div>
1243            <div class="note" id="rfc.section.6.3.p.10">
1244               <p><b>Note:</b> Most HTTP/1.0 applications do not recognize or obey qvalues associated with content-codings. This means that qvalues will
1245                  not work and are not permitted with x-gzip or x-compress.
1246               </p>
1247            </div>
1248         </div>
1249         <div id="header.accept-language">
1250            <div id="rfc.iref.a.4"></div>
1251            <div id="rfc.iref.h.4"></div>
1252            <h2 id="rfc.section.6.4"><a href="#rfc.section.6.4">6.4</a>&nbsp;<a href="#header.accept-language">Accept-Language</a></h2>
1253            <p id="rfc.section.6.4.p.1">The "Accept-Language" header field can be used by user agents to indicate the set of natural languages that are preferred
1254               in the response. Language tags are defined in <a href="#language.tags" title="Language Tags">Section&nbsp;2.4</a>.
1255            </p>
1256            <div id="rfc.figure.u.19"></div><pre class="inline"><span id="rfc.iref.g.18"></span><span id="rfc.iref.g.19"></span>  <a href="#header.accept-language" class="smpl">Accept-Language</a> =
1257                    1#( <a href="#header.accept-language" class="smpl">language-range</a> [ <a href="#core.rules" class="smpl">OWS</a> ";" <a href="#core.rules" class="smpl">OWS</a> "q=" <a href="#abnf.dependencies" class="smpl">qvalue</a> ] )
1258  <a href="#header.accept-language" class="smpl">language-range</a>  =
1259            &lt;language-range, defined in <a href="#RFC4647" id="rfc.xref.RFC4647.1"><cite title="Matching of Language Tags">[RFC4647]</cite></a>, <a href="https://tools.ietf.org/html/rfc4647#section-2.1">Section 2.1</a>&gt;
1260</pre><p id="rfc.section.6.4.p.3">Each language-range can be given an associated quality value which represents an estimate of the user's preference for the
1261               languages specified by that range. The quality value defaults to "q=1". For example,
1262            </p>
1263            <div id="rfc.figure.u.20"></div><pre class="text">  Accept-Language: da, en-gb;q=0.8, en;q=0.7
1264</pre><p id="rfc.section.6.4.p.5">would mean: "I prefer Danish, but will accept British English and other types of English". (see also <a href="https://tools.ietf.org/html/rfc4647#section-2.3">Section 2.3</a> of <a href="#RFC4647" id="rfc.xref.RFC4647.2"><cite title="Matching of Language Tags">[RFC4647]</cite></a>)
1265            </p>
1266            <p id="rfc.section.6.4.p.6">For matching, <a href="https://tools.ietf.org/html/rfc4647#section-3">Section 3</a> of <a href="#RFC4647" id="rfc.xref.RFC4647.3"><cite title="Matching of Language Tags">[RFC4647]</cite></a> defines several matching schemes. Implementations can offer the most appropriate matching scheme for their requirements.
1267            </p>
1268            <div class="note" id="rfc.section.6.4.p.7">
1269               <p><b>Note:</b> The "Basic Filtering" scheme (<a href="#RFC4647" id="rfc.xref.RFC4647.4"><cite title="Matching of Language Tags">[RFC4647]</cite></a>, <a href="https://tools.ietf.org/html/rfc4647#section-3.3.1">Section 3.3.1</a>) is identical to the matching scheme that was previously defined in <a href="https://tools.ietf.org/html/rfc2616#section-14.4">Section 14.4</a> of <a href="#RFC2616" id="rfc.xref.RFC2616.2"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>.
1270               </p>
1271            </div>
1272            <p id="rfc.section.6.4.p.8">It might be contrary to the privacy expectations of the user to send an Accept-Language header field with the complete linguistic
1273               preferences of the user in every request. For a discussion of this issue, see <a href="#privacy.issues.connected.to.accept.header.fields" title="Privacy Issues Connected to Accept Header Fields">Section&nbsp;8.1</a>.
1274            </p>
1275            <p id="rfc.section.6.4.p.9">As intelligibility is highly dependent on the individual user, it is recommended that client applications make the choice
1276               of linguistic preference available to the user. If the choice is not made available, then the Accept-Language header field <em class="bcp14">MUST NOT</em> be given in the request.
1277            </p>
1278            <div class="note" id="rfc.section.6.4.p.10">
1279               <p><b>Note:</b> When making the choice of linguistic preference available to the user, we remind implementors of the fact that users are not
1280                  familiar with the details of language matching as described above, and ought to be provided appropriate guidance. As an example,
1281                  users might assume that on selecting "en-gb", they will be served any kind of English document if British English is not available.
1282                  A user agent might suggest in such a case to add "en" to get the best matching behavior.
1283               </p>
1284            </div>
1285         </div>
1286         <div id="header.content-encoding">
1287            <div id="rfc.iref.c.7"></div>
1288            <div id="rfc.iref.h.5"></div>
1289            <h2 id="rfc.section.6.5"><a href="#rfc.section.6.5">6.5</a>&nbsp;<a href="#header.content-encoding">Content-Encoding</a></h2>
1290            <p id="rfc.section.6.5.p.1">The "Content-Encoding" header field indicates what content-codings have been applied to the representation, and thus what
1291               decoding mechanisms must be applied in order to obtain the media-type referenced by the Content-Type header field. Content-Encoding
1292               is primarily used to allow a representation to be compressed without losing the identity of its underlying media type.
1293            </p>
1294            <div id="rfc.figure.u.21"></div><pre class="inline"><span id="rfc.iref.g.20"></span>  <a href="#header.content-encoding" class="smpl">Content-Encoding</a> = 1#<a href="#content.codings" class="smpl">content-coding</a>
1295</pre><p id="rfc.section.6.5.p.3">Content codings are defined in <a href="#content.codings" title="Content Codings">Section&nbsp;2.2</a>. An example of its use is
1296            </p>
1297            <div id="rfc.figure.u.22"></div><pre class="text">  Content-Encoding: gzip
1298</pre><p id="rfc.section.6.5.p.5">The content-coding is a characteristic of the representation. Typically, the representation body is stored with this encoding
1299               and is only decoded before rendering or analogous usage. However, a transforming proxy <em class="bcp14">MAY</em> modify the content-coding if the new coding is known to be acceptable to the recipient, unless the "no-transform" cache-control
1300               directive is present in the message.
1301            </p>
1302            <p id="rfc.section.6.5.p.6">If the content-coding of a representation is not "identity", then the representation metadata <em class="bcp14">MUST</em> include a Content-Encoding header field (<a href="#header.content-encoding" id="rfc.xref.header.content-encoding.3" title="Content-Encoding">Section&nbsp;6.5</a>) that lists the non-identity content-coding(s) used.
1303            </p>
1304            <p id="rfc.section.6.5.p.7">If the content-coding of a representation in a request message is not acceptable to the origin server, the server <em class="bcp14">SHOULD</em> respond with a status code of 415 (Unsupported Media Type).
1305            </p>
1306            <p id="rfc.section.6.5.p.8">If multiple encodings have been applied to a representation, the content codings <em class="bcp14">MUST</em> be listed in the order in which they were applied. Additional information about the encoding parameters <em class="bcp14">MAY</em> be provided by other header fields not defined by this specification.
1307            </p>
1308         </div>
1309         <div id="header.content-language">
1310            <div id="rfc.iref.c.8"></div>
1311            <div id="rfc.iref.h.6"></div>
1312            <h2 id="rfc.section.6.6"><a href="#rfc.section.6.6">6.6</a>&nbsp;<a href="#header.content-language">Content-Language</a></h2>
1313            <p id="rfc.section.6.6.p.1">The "Content-Language" header field describes the natural language(s) of the intended audience for the representation. Note
1314               that this might not be equivalent to all the languages used within the representation.
1315            </p>
1316            <div id="rfc.figure.u.23"></div><pre class="inline"><span id="rfc.iref.g.21"></span>  <a href="#header.content-language" class="smpl">Content-Language</a> = 1#<a href="#language.tags" class="smpl">language-tag</a>
1317</pre><p id="rfc.section.6.6.p.3">Language tags are defined in <a href="#language.tags" title="Language Tags">Section&nbsp;2.4</a>. The primary purpose of Content-Language is to allow a user to identify and differentiate representations according to the
1318               user's own preferred language. Thus, if the body content is intended only for a Danish-literate audience, the appropriate
1319               field is
1320            </p>
1321            <div id="rfc.figure.u.24"></div><pre class="text">  Content-Language: da
1322</pre><p id="rfc.section.6.6.p.5">If no Content-Language is specified, the default is that the content is intended for all language audiences. This might mean
1323               that the sender does not consider it to be specific to any natural language, or that the sender does not know for which language
1324               it is intended.
1325            </p>
1326            <p id="rfc.section.6.6.p.6">Multiple languages <em class="bcp14">MAY</em> be listed for content that is intended for multiple audiences. For example, a rendition of the "Treaty of Waitangi", presented
1327               simultaneously in the original Maori and English versions, would call for
1328            </p>
1329            <div id="rfc.figure.u.25"></div><pre class="text">  Content-Language: mi, en
1330</pre><p id="rfc.section.6.6.p.8">However, just because multiple languages are present within a representation does not mean that it is intended for multiple
1331               linguistic audiences. An example would be a beginner's language primer, such as "A First Lesson in Latin", which is clearly
1332               intended to be used by an English-literate audience. In this case, the Content-Language would properly only include "en".
1333            </p>
1334            <p id="rfc.section.6.6.p.9">Content-Language <em class="bcp14">MAY</em> be applied to any media type — it is not limited to textual documents.
1335            </p>
1336         </div>
1337         <div id="header.content-location">
1338            <div id="rfc.iref.c.9"></div>
1339            <div id="rfc.iref.h.7"></div>
1340            <h2 id="rfc.section.6.7"><a href="#rfc.section.6.7">6.7</a>&nbsp;<a href="#header.content-location">Content-Location</a></h2>
1341            <p id="rfc.section.6.7.p.1">The "Content-Location" header field supplies a URI that can be used as a specific identifier for the representation in this
1342               message. In other words, if one were to perform a GET on this URI at the time of this message's generation, then a 200 response
1343               would contain the same representation that is enclosed as payload in this message.
1344            </p>
1345            <div id="rfc.figure.u.26"></div><pre class="inline"><span id="rfc.iref.g.22"></span>  <a href="#header.content-location" class="smpl">Content-Location</a> = <a href="#abnf.dependencies" class="smpl">absolute-URI</a> / <a href="#abnf.dependencies" class="smpl">partial-URI</a>
1346</pre><p id="rfc.section.6.7.p.3">The Content-Location value is not a replacement for 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.Part1.18"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). It is representation metadata. It has the same syntax and semantics as the header field of the same name defined for MIME
1347               body parts in <a href="https://tools.ietf.org/html/rfc2557#section-4">Section 4</a> of <a href="#RFC2557" id="rfc.xref.RFC2557.1"><cite title="MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)">[RFC2557]</cite></a>. However, its appearance in an HTTP message has some special implications for HTTP recipients.
1348            </p>
1349            <p id="rfc.section.6.7.p.4">If Content-Location is included in a response message and its value is the same as the effective request URI, then the response
1350               payload <em class="bcp14">SHOULD</em> be considered the current representation of that resource. For a GET or HEAD request, this is the same as the default semantics
1351               when no Content-Location is provided by the server. For a state-changing request like PUT or POST, it implies that the server's
1352               response contains the new representation of that resource, thereby distinguishing it from representations that might only
1353               report about the action (e.g., "It worked!"). This allows authoring applications to update their local copies without the
1354               need for a subsequent GET request.
1355            </p>
1356            <p id="rfc.section.6.7.p.5">If Content-Location is included in a response message and its value differs from the effective request URI, then the origin
1357               server is informing recipients that this representation has its own, presumably more specific, identifier. For a GET or HEAD
1358               request, this is an indication that the effective request URI identifies a resource that is subject to content negotiation
1359               and the representation selected for this response can also be found at the identified URI. For other methods, such a Content-Location
1360               indicates that this representation contains a report on the action's status and the same report is available (for future access
1361               with GET) at the given URI. For example, a purchase transaction made via a POST request might include a receipt document as
1362               the payload of the 200 response; the Content-Location value provides an identifier for retrieving a copy of that same receipt
1363               in the future.
1364            </p>
1365            <p id="rfc.section.6.7.p.6">If Content-Location is included in a request message, then it <em class="bcp14">MAY</em> be interpreted by the origin server as an indication of where the user agent originally obtained the content of the enclosed
1366               representation (prior to any subsequent modification of the content by that user agent). In other words, the user agent is
1367               providing the same representation metadata that it received with the original representation. However, such interpretation <em class="bcp14">MUST NOT</em> be used to alter the semantics of the method requested by the client. For example, if a client makes a PUT request on a negotiated
1368               resource and the origin server accepts that PUT (without redirection), then the new set of values for that resource is expected
1369               to be consistent with the one representation supplied in that PUT; the Content-Location cannot be used as a form of reverse
1370               content selection that identifies only one of the negotiated representations to be updated. If the user agent had wanted the
1371               latter semantics, it would have applied the PUT directly to the Content-Location URI.
1372            </p>
1373            <p id="rfc.section.6.7.p.7">A Content-Location field received in a request message is transitory information that <em class="bcp14">SHOULD NOT</em> be saved with other representation metadata for use in later responses. The Content-Location's value might be saved for use
1374               in other contexts, such as within source links or other metadata.
1375            </p>
1376            <p id="rfc.section.6.7.p.8">A cache cannot assume that a representation with a Content-Location different from the URI used to retrieve it can be used
1377               to respond to later requests on that Content-Location URI.
1378            </p>
1379            <p id="rfc.section.6.7.p.9">If the Content-Location value is a partial URI, the partial URI is interpreted relative to the effective request URI.</p>
1380         </div>
1381         <div id="header.content-type">
1382            <div id="rfc.iref.c.10"></div>
1383            <div id="rfc.iref.h.8"></div>
1384            <h2 id="rfc.section.6.8"><a href="#rfc.section.6.8">6.8</a>&nbsp;<a href="#header.content-type">Content-Type</a></h2>
1385            <p id="rfc.section.6.8.p.1">The "Content-Type" header field indicates the media type of the representation. In the case of responses to the HEAD method,
1386               the media type is that which would have been sent had the request been a GET.
1387            </p>
1388            <div id="rfc.figure.u.27"></div><pre class="inline"><span id="rfc.iref.g.23"></span>  <a href="#header.content-type" class="smpl">Content-Type</a> = <a href="#media.types" class="smpl">media-type</a>
1389</pre><p id="rfc.section.6.8.p.3">Media types are defined in <a href="#media.types" title="Media Types">Section&nbsp;2.3</a>. An example of the field is
1390            </p>
1391            <div id="rfc.figure.u.28"></div><pre class="text">  Content-Type: text/html; charset=ISO-8859-4
1392</pre><p id="rfc.section.6.8.p.5">Further discussion of Content-Type is provided in <a href="#representation.data" title="Representation Data">Section&nbsp;4.2</a>.
1393            </p>
1394         </div>
1395      </div>
1396      <div id="IANA.considerations">
1397         <h1 id="rfc.section.7"><a href="#rfc.section.7">7.</a>&nbsp;<a href="#IANA.considerations">IANA Considerations</a></h1>
1398         <div id="header.field.registration">
1399            <h2 id="rfc.section.7.1"><a href="#rfc.section.7.1">7.1</a>&nbsp;<a href="#header.field.registration">Header Field Registration</a></h2>
1400            <p id="rfc.section.7.1.p.1">The Message Header Field 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; shall 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>):
1401            </p>
1402            <div id="rfc.table.1">
1403               <div id="iana.header.registration.table"></div>
1404               <table class="tt full left" cellpadding="3" cellspacing="0">
1405                  <thead>
1406                     <tr>
1407                        <th>Header Field Name</th>
1408                        <th>Protocol</th>
1409                        <th>Status</th>
1410                        <th>Reference</th>
1411                     </tr>
1412                  </thead>
1413                  <tbody>
1414                     <tr>
1415                        <td class="left">Accept</td>
1416                        <td class="left">http</td>
1417                        <td class="left">standard</td>
1418                        <td class="left"><a href="#header.accept" id="rfc.xref.header.accept.3" title="Accept">Section&nbsp;6.1</a>
1419                        </td>
1420                     </tr>
1421                     <tr>
1422                        <td class="left">Accept-Charset</td>
1423                        <td class="left">http</td>
1424                        <td class="left">standard</td>
1425                        <td class="left"><a href="#header.accept-charset" id="rfc.xref.header.accept-charset.2" title="Accept-Charset">Section&nbsp;6.2</a>
1426                        </td>
1427                     </tr>
1428                     <tr>
1429                        <td class="left">Accept-Encoding</td>
1430                        <td class="left">http</td>
1431                        <td class="left">standard</td>
1432                        <td class="left"><a href="#header.accept-encoding" id="rfc.xref.header.accept-encoding.3" title="Accept-Encoding">Section&nbsp;6.3</a>
1433                        </td>
1434                     </tr>
1435                     <tr>
1436                        <td class="left">Accept-Language</td>
1437                        <td class="left">http</td>
1438                        <td class="left">standard</td>
1439                        <td class="left"><a href="#header.accept-language" id="rfc.xref.header.accept-language.2" title="Accept-Language">Section&nbsp;6.4</a>
1440                        </td>
1441                     </tr>
1442                     <tr>
1443                        <td class="left">Content-Encoding</td>
1444                        <td class="left">http</td>
1445                        <td class="left">standard</td>
1446                        <td class="left"><a href="#header.content-encoding" id="rfc.xref.header.content-encoding.4" title="Content-Encoding">Section&nbsp;6.5</a>
1447                        </td>
1448                     </tr>
1449                     <tr>
1450                        <td class="left">Content-Language</td>
1451                        <td class="left">http</td>
1452                        <td class="left">standard</td>
1453                        <td class="left"><a href="#header.content-language" id="rfc.xref.header.content-language.2" title="Content-Language">Section&nbsp;6.6</a>
1454                        </td>
1455                     </tr>
1456                     <tr>
1457                        <td class="left">Content-Location</td>
1458                        <td class="left">http</td>
1459                        <td class="left">standard</td>
1460                        <td class="left"><a href="#header.content-location" id="rfc.xref.header.content-location.2" title="Content-Location">Section&nbsp;6.7</a>
1461                        </td>
1462                     </tr>
1463                     <tr>
1464                        <td class="left">Content-Type</td>
1465                        <td class="left">http</td>
1466                        <td class="left">standard</td>
1467                        <td class="left"><a href="#header.content-type" id="rfc.xref.header.content-type.3" title="Content-Type">Section&nbsp;6.8</a>
1468                        </td>
1469                     </tr>
1470                     <tr>
1471                        <td class="left">MIME-Version</td>
1472                        <td class="left">http</td>
1473                        <td class="left">standard</td>
1474                        <td class="left"><a href="#mime-version" id="rfc.xref.mime-version.1" title="MIME-Version">Appendix&nbsp;A.1</a>
1475                        </td>
1476                     </tr>
1477                  </tbody>
1478               </table>
1479            </div>
1480            <p id="rfc.section.7.1.p.2">The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".</p>
1481         </div>
1482         <div id="content.coding.registration">
1483            <h2 id="rfc.section.7.2"><a href="#rfc.section.7.2">7.2</a>&nbsp;<a href="#content.coding.registration">Content Coding Registry</a></h2>
1484            <p id="rfc.section.7.2.p.1">The registration procedure for HTTP Content Codings is now defined by <a href="#content.coding.registry" title="Content Coding Registry">Section&nbsp;2.2.1</a> of this document.
1485            </p>
1486            <p id="rfc.section.7.2.p.2">The HTTP Content Codings Registry located at &lt;<a href="http://www.iana.org/assignments/http-parameters">http://www.iana.org/assignments/http-parameters</a>&gt; shall be updated with the registration below:
1487            </p>
1488            <div id="rfc.table.2">
1489               <div id="iana.content.coding.registration.table"></div>
1490               <table class="tt full left" cellpadding="3" cellspacing="0">
1491                  <thead>
1492                     <tr>
1493                        <th>Name</th>
1494                        <th>Description</th>
1495                        <th>Reference</th>
1496                     </tr>
1497                  </thead>
1498                  <tbody>
1499                     <tr>
1500                        <td class="left">compress</td>
1501                        <td class="left">UNIX "compress" program method</td>
1502                        <td class="left"><a href="p1-messaging.html#compress.coding" title="Compress Coding">Section 6.2.2.1</a> of <a href="#Part1" id="rfc.xref.Part1.19"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>
1503                        </td>
1504                     </tr>
1505                     <tr>
1506                        <td class="left">deflate</td>
1507                        <td class="left">"deflate" compression mechanism (<a href="#RFC1951" id="rfc.xref.RFC1951.1"><cite title="DEFLATE Compressed Data Format Specification version 1.3">[RFC1951]</cite></a>) used inside the "zlib" data format (<a href="#RFC1950" id="rfc.xref.RFC1950.1"><cite title="ZLIB Compressed Data Format Specification version 3.3">[RFC1950]</cite></a>)
1508                        </td>
1509                        <td class="left"><a href="p1-messaging.html#deflate.coding" title="Deflate Coding">Section 6.2.2.2</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>
1510                        </td>
1511                     </tr>
1512                     <tr>
1513                        <td class="left">gzip</td>
1514                        <td class="left">Same as GNU zip <a href="#RFC1952" id="rfc.xref.RFC1952.1"><cite title="GZIP file format specification version 4.3">[RFC1952]</cite></a></td>
1515                        <td class="left"><a href="p1-messaging.html#gzip.coding" title="Gzip Coding">Section 6.2.2.3</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>
1516                        </td>
1517                     </tr>
1518                     <tr>
1519                        <td class="left">identity</td>
1520                        <td class="left">No transformation</td>
1521                        <td class="left"><a href="#content.codings" title="Content Codings">Section&nbsp;2.2</a>
1522                        </td>
1523                     </tr>
1524                  </tbody>
1525               </table>
1526            </div>
1527         </div>
1528      </div>
1529      <div id="security.considerations">
1530         <h1 id="rfc.section.8"><a href="#rfc.section.8">8.</a>&nbsp;<a href="#security.considerations">Security Considerations</a></h1>
1531         <p id="rfc.section.8.p.1">This section is meant to inform application developers, information providers, and users of the security limitations in HTTP/1.1
1532            as described by this document. The discussion does not include definitive solutions to the problems revealed, though it does
1533            make some suggestions for reducing security risks.
1534         </p>
1535         <div id="privacy.issues.connected.to.accept.header.fields">
1536            <h2 id="rfc.section.8.1"><a href="#rfc.section.8.1">8.1</a>&nbsp;<a href="#privacy.issues.connected.to.accept.header.fields">Privacy Issues Connected to Accept Header Fields</a></h2>
1537            <p id="rfc.section.8.1.p.1">Accept headers fields can reveal information about the user to all servers which are accessed. The Accept-Language header
1538               field in particular can reveal information the user would consider to be of a private nature, because the understanding of
1539               particular languages is often strongly correlated to the membership of a particular ethnic group. User agents which offer
1540               the option to configure the contents of an Accept-Language header field to be sent in every request are strongly encouraged
1541               to let the configuration process include a message which makes the user aware of the loss of privacy involved.
1542            </p>
1543            <p id="rfc.section.8.1.p.2">An approach that limits the loss of privacy would be for a user agent to omit the sending of Accept-Language header fields
1544               by default, and to ask the user whether or not to start sending Accept-Language header fields to a server if it detects, by
1545               looking for any Vary header fields generated by the server, that such sending could improve the quality of service.
1546            </p>
1547            <p id="rfc.section.8.1.p.3">Elaborate user-customized accept header fields sent in every request, in particular if these include quality values, can be
1548               used by servers as relatively reliable and long-lived user identifiers. Such user identifiers would allow content providers
1549               to do click-trail tracking, and would allow collaborating content providers to match cross-server click-trails or form submissions
1550               of individual users. Note that for many users not behind a proxy, the network address of the host running the user agent will
1551               also serve as a long-lived user identifier. In environments where proxies are used to enhance privacy, user agents ought to
1552               be conservative in offering accept header configuration options to end users. As an extreme privacy measure, proxies could
1553               filter the accept header fields in relayed requests. General purpose user agents which provide a high degree of header configurability <em class="bcp14">SHOULD</em> warn users about the loss of privacy which can be involved.
1554            </p>
1555         </div>
1556      </div>
1557      <div id="ack">
1558         <h1 id="rfc.section.9"><a href="#rfc.section.9">9.</a>&nbsp;<a href="#ack">Acknowledgments</a></h1>
1559      </div>
1560      <h1 id="rfc.references"><a id="rfc.section.10" href="#rfc.section.10">10.</a> References
1561      </h1>
1562      <h2 id="rfc.references.1"><a href="#rfc.section.10.1" id="rfc.section.10.1">10.1</a> Normative References
1563      </h2>
1564      <table>
1565         <tr>
1566            <td class="reference"><b id="Part1">[Part1]</b></td>
1567            <td class="top"><a href="mailto:fielding@gbiv.com" title="Adobe Systems Incorporated">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-14">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p1-messaging-14 (work in progress), April&nbsp;2011.
1568            </td>
1569         </tr>
1570         <tr>
1571            <td class="reference"><b id="Part2">[Part2]</b></td>
1572            <td class="top"><a href="mailto:fielding@gbiv.com" title="Adobe Systems Incorporated">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-p2-semantics-14">HTTP/1.1, part 2: Message Semantics</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p2-semantics-14 (work in progress), April&nbsp;2011.
1573            </td>
1574         </tr>
1575         <tr>
1576            <td class="reference"><b id="Part4">[Part4]</b></td>
1577            <td class="top"><a href="mailto:fielding@gbiv.com" title="Adobe Systems Incorporated">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-14">HTTP/1.1, part 4: Conditional Requests</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p4-conditional-14 (work in progress), April&nbsp;2011.
1578            </td>
1579         </tr>
1580         <tr>
1581            <td class="reference"><b id="Part5">[Part5]</b></td>
1582            <td class="top"><a href="mailto:fielding@gbiv.com" title="Adobe Systems Incorporated">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-14">HTTP/1.1, part 5: Range Requests and Partial Responses</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p5-range-14 (work in progress), April&nbsp;2011.
1583            </td>
1584         </tr>
1585         <tr>
1586            <td class="reference"><b id="Part6">[Part6]</b></td>
1587            <td class="top"><a href="mailto:fielding@gbiv.com" title="Adobe Systems Incorporated">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-14">HTTP/1.1, part 6: Caching</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p6-cache-14 (work in progress), April&nbsp;2011.
1588            </td>
1589         </tr>
1590         <tr>
1591            <td class="reference"><b id="RFC1950">[RFC1950]</b></td>
1592            <td class="top"><a href="mailto:ghost@aladdin.com" title="Aladdin Enterprises">Deutsch, L.</a> and J-L. Gailly, “<a href="https://tools.ietf.org/html/rfc1950">ZLIB Compressed Data Format Specification version 3.3</a>”, RFC&nbsp;1950, May&nbsp;1996.<br>RFC 1950 is an Informational RFC, thus it might be less stable than this specification. On the other hand, this downward reference
1593               was present since the publication of RFC 2068 in 1997 (<a href="#RFC2068" id="rfc.xref.RFC2068.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a>), therefore it is unlikely to cause problems in practice. See also <a href="#BCP97" id="rfc.xref.BCP97.1"><cite title="Handling Normative References to Standards-Track Documents">[BCP97]</cite></a>.
1594            </td>
1595         </tr>
1596         <tr>
1597            <td class="reference"><b id="RFC1951">[RFC1951]</b></td>
1598            <td class="top"><a href="mailto:ghost@aladdin.com" title="Aladdin Enterprises">Deutsch, P.</a>, “<a href="https://tools.ietf.org/html/rfc1951">DEFLATE Compressed Data Format Specification version 1.3</a>”, RFC&nbsp;1951, May&nbsp;1996.<br>RFC 1951 is an Informational RFC, thus it might be less stable than this specification. On the other hand, this downward reference
1599               was present since the publication of RFC 2068 in 1997 (<a href="#RFC2068" id="rfc.xref.RFC2068.2"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a>), therefore it is unlikely to cause problems in practice. See also <a href="#BCP97" id="rfc.xref.BCP97.2"><cite title="Handling Normative References to Standards-Track Documents">[BCP97]</cite></a>.
1600            </td>
1601         </tr>
1602         <tr>
1603            <td class="reference"><b id="RFC1952">[RFC1952]</b></td>
1604            <td class="top"><a href="mailto:ghost@aladdin.com" title="Aladdin Enterprises">Deutsch, P.</a>, <a href="mailto:gzip@prep.ai.mit.edu">Gailly, J-L.</a>, <a href="mailto:madler@alumni.caltech.edu">Adler, M.</a>, <a href="mailto:ghost@aladdin.com">Deutsch, L.</a>, and <a href="mailto:randeg@alumni.rpi.edu">G. Randers-Pehrson</a>, “<a href="https://tools.ietf.org/html/rfc1952">GZIP file format specification version 4.3</a>”, RFC&nbsp;1952, May&nbsp;1996.<br>RFC 1952 is an Informational RFC, thus it might be less stable than this specification. On the other hand, this downward reference
1605               was present since the publication of RFC 2068 in 1997 (<a href="#RFC2068" id="rfc.xref.RFC2068.3"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a>), therefore it is unlikely to cause problems in practice. See also <a href="#BCP97" id="rfc.xref.BCP97.3"><cite title="Handling Normative References to Standards-Track Documents">[BCP97]</cite></a>.
1606            </td>
1607         </tr>
1608         <tr>
1609            <td class="reference"><b id="RFC2045">[RFC2045]</b></td>
1610            <td class="top"><a href="mailto:ned@innosoft.com" title="Innosoft International, Inc.">Freed, N.</a> and <a href="mailto:nsb@nsb.fv.com" title="First Virtual Holdings">N. Borenstein</a>, “<a href="https://tools.ietf.org/html/rfc2045">Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</a>”, RFC&nbsp;2045, November&nbsp;1996.
1611            </td>
1612         </tr>
1613         <tr>
1614            <td class="reference"><b id="RFC2046">[RFC2046]</b></td>
1615            <td class="top"><a href="mailto:ned@innosoft.com" title="Innosoft International, Inc.">Freed, N.</a> and <a href="mailto:nsb@nsb.fv.com" title="First Virtual Holdings">N. Borenstein</a>, “<a href="https://tools.ietf.org/html/rfc2046">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</a>”, RFC&nbsp;2046, November&nbsp;1996.
1616            </td>
1617         </tr>
1618         <tr>
1619            <td class="reference"><b id="RFC2119">[RFC2119]</b></td>
1620            <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.
1621            </td>
1622         </tr>
1623         <tr>
1624            <td class="reference"><b id="RFC4647">[RFC4647]</b></td>
1625            <td class="top"><a href="mailto:addison@inter-locale.com" title="Yahoo! Inc.">Phillips, A., Ed.</a> and <a href="mailto:mark.davis@macchiato.com" title="Google">M. Davis, Ed.</a>, “<a href="https://tools.ietf.org/html/rfc4647">Matching of Language Tags</a>”, BCP&nbsp;47, RFC&nbsp;4647, September&nbsp;2006.
1626            </td>
1627         </tr>
1628         <tr>
1629            <td class="reference"><b id="RFC5234">[RFC5234]</b></td>
1630            <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.
1631            </td>
1632         </tr>
1633         <tr>
1634            <td class="reference"><b id="RFC5646">[RFC5646]</b></td>
1635            <td class="top"><a href="mailto:addison@inter-locale.com" title="Lab126">Phillips, A., Ed.</a> and <a href="mailto:mark.davis@google.com" title="Google">M. Davis, Ed.</a>, “<a href="https://tools.ietf.org/html/rfc5646">Tags for Identifying Languages</a>”, BCP&nbsp;47, RFC&nbsp;5646, September&nbsp;2009.
1636            </td>
1637         </tr>
1638      </table>
1639      <h2 id="rfc.references.2"><a href="#rfc.section.10.2" id="rfc.section.10.2">10.2</a> Informative References
1640      </h2>
1641      <table>
1642         <tr>
1643            <td class="reference"><b id="BCP97">[BCP97]</b></td>
1644            <td class="top"><a href="mailto:klensin+ietf@jck.com">Klensin, J.</a> and <a href="mailto:hartmans-ietf@mit.edu" title="MIT">S. Hartman</a>, “<a href="https://tools.ietf.org/html/rfc4897">Handling Normative References to Standards-Track Documents</a>”, BCP&nbsp;97, RFC&nbsp;4897, June&nbsp;2007.
1645            </td>
1646         </tr>
1647         <tr>
1648            <td class="reference"><b id="RFC1945">[RFC1945]</b></td>
1649            <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.
1650            </td>
1651         </tr>
1652         <tr>
1653            <td class="reference"><b id="RFC2049">[RFC2049]</b></td>
1654            <td class="top"><a href="mailto:ned@innosoft.com" title="Innosoft International, Inc.">Freed, N.</a> and <a href="mailto:nsb@nsb.fv.com" title="First Virtual Holdings">N. Borenstein</a>, “<a href="https://tools.ietf.org/html/rfc2049">Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples</a>”, RFC&nbsp;2049, November&nbsp;1996.
1655            </td>
1656         </tr>
1657         <tr>
1658            <td class="reference"><b id="RFC2068">[RFC2068]</b></td>
1659            <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.
1660            </td>
1661         </tr>
1662         <tr>
1663            <td class="reference"><b id="RFC2076">[RFC2076]</b></td>
1664            <td class="top"><a href="mailto:jpalme@dsv.su.se" title="Stockholm University/KTH">Palme, J.</a>, “<a href="https://tools.ietf.org/html/rfc2076">Common Internet Message Headers</a>”, RFC&nbsp;2076, February&nbsp;1997.
1665            </td>
1666         </tr>
1667         <tr>
1668            <td class="reference"><b id="RFC2277">[RFC2277]</b></td>
1669            <td class="top"><a href="mailto:Harald.T.Alvestrand@uninett.no" title="UNINETT">Alvestrand, H.</a>, “<a href="https://tools.ietf.org/html/rfc2277">IETF Policy on Character Sets and Languages</a>”, BCP&nbsp;18, RFC&nbsp;2277, January&nbsp;1998.
1670            </td>
1671         </tr>
1672         <tr>
1673            <td class="reference"><b id="RFC2295">[RFC2295]</b></td>
1674            <td class="top"><a href="mailto:koen@win.tue.nl" title="Technische Universiteit Eindhoven">Holtman, K.</a> and <a href="mailto:mutz@hpl.hp.com" title="Hewlett-Packard Company">A. Mutz</a>, “<a href="https://tools.ietf.org/html/rfc2295">Transparent Content Negotiation in HTTP</a>”, RFC&nbsp;2295, March&nbsp;1998.
1675            </td>
1676         </tr>
1677         <tr>
1678            <td class="reference"><b id="RFC2388">[RFC2388]</b></td>
1679            <td class="top"><a href="mailto:masinter@parc.xerox.com" title="Xerox Palo Alto Research Center">Masinter, L.</a>, “<a href="https://tools.ietf.org/html/rfc2388">Returning Values from Forms: multipart/form-data</a>”, RFC&nbsp;2388, August&nbsp;1998.
1680            </td>
1681         </tr>
1682         <tr>
1683            <td class="reference"><b id="RFC2557">[RFC2557]</b></td>
1684            <td class="top"><a href="mailto:jpalme@dsv.su.se" title="Stockholm University and KTH">Palme, F.</a>, <a href="mailto:alexhop@microsoft.com" title="Microsoft Corporation">Hopmann, A.</a>, <a href="mailto:Shelness@lotus.com" title="Lotus Development Corporation">Shelness, N.</a>, and <a href="mailto:stef@nma.com">E. Stefferud</a>, “<a href="https://tools.ietf.org/html/rfc2557">MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)</a>”, RFC&nbsp;2557, March&nbsp;1999.
1685            </td>
1686         </tr>
1687         <tr>
1688            <td class="reference"><b id="RFC2616">[RFC2616]</b></td>
1689            <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.
1690            </td>
1691         </tr>
1692         <tr>
1693            <td class="reference"><b id="RFC3629">[RFC3629]</b></td>
1694            <td class="top"><a href="mailto:fyergeau@alis.com" title="Alis Technologies">Yergeau, F.</a>, “<a href="https://tools.ietf.org/html/rfc3629">UTF-8, a transformation format of ISO 10646</a>”, STD&nbsp;63, RFC&nbsp;3629, November&nbsp;2003.
1695            </td>
1696         </tr>
1697         <tr>
1698            <td class="reference"><b id="RFC3864">[RFC3864]</b></td>
1699            <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.
1700            </td>
1701         </tr>
1702         <tr>
1703            <td class="reference"><b id="RFC4288">[RFC4288]</b></td>
1704            <td class="top"><a href="mailto:ned.freed@mrochek.com" title="Sun Microsystems">Freed, N.</a> and <a href="mailto:klensin+ietf@jck.com">J. Klensin</a>, “<a href="https://tools.ietf.org/html/rfc4288">Media Type Specifications and Registration Procedures</a>”, BCP&nbsp;13, RFC&nbsp;4288, December&nbsp;2005.
1705            </td>
1706         </tr>
1707         <tr>
1708            <td class="reference"><b id="RFC5226">[RFC5226]</b></td>
1709            <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.
1710            </td>
1711         </tr>
1712         <tr>
1713            <td class="reference"><b id="RFC5322">[RFC5322]</b></td>
1714            <td class="top">Resnick, P., “<a href="https://tools.ietf.org/html/rfc5322">Internet Message Format</a>”, RFC&nbsp;5322, October&nbsp;2008.
1715            </td>
1716         </tr>
1717         <tr>
1718            <td class="reference"><b id="RFC6151">[RFC6151]</b></td>
1719            <td class="top">Turner, S. and L. Chen, “<a href="https://tools.ietf.org/html/rfc6151">Updated Security Considerations for the MD5 Message-Digest and the HMAC-MD5 Algorithms</a>”, RFC&nbsp;6151, March&nbsp;2011.
1720            </td>
1721         </tr>
1722         <tr>
1723            <td class="reference"><b id="draft-ietf-httpbis-content-disp">[draft-ietf-httpbis-content-disp]</b></td>
1724            <td class="top"><a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">Reschke, J.</a>, “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-content-disp-09">Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-content-disp-09 (work in progress), March&nbsp;2011.
1725            </td>
1726         </tr>
1727      </table>
1728      <div id="differences.between.http.and.mime">
1729         <h1 id="rfc.section.A" class="np"><a href="#rfc.section.A">A.</a>&nbsp;<a href="#differences.between.http.and.mime">Differences between HTTP and MIME</a></h1>
1730         <p id="rfc.section.A.p.1">HTTP/1.1 uses many of the constructs defined for Internet Mail (<a href="#RFC5322" id="rfc.xref.RFC5322.1"><cite title="Internet Message Format">[RFC5322]</cite></a>) and the Multipurpose Internet Mail Extensions (MIME <a href="#RFC2045" id="rfc.xref.RFC2045.1"><cite title="Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies">[RFC2045]</cite></a>) to allow a message-body to be transmitted in an open variety of representations and with extensible mechanisms. However,
1731            RFC 2045 discusses mail, and HTTP has a few features that are different from those described in MIME. These differences were
1732            carefully chosen to optimize performance over binary connections, to allow greater freedom in the use of new media types,
1733            to make date comparisons easier, and to acknowledge the practice of some early HTTP servers and clients.
1734         </p>
1735         <p id="rfc.section.A.p.2">This appendix describes specific areas where HTTP differs from MIME. Proxies and gateways to strict MIME environments <em class="bcp14">SHOULD</em> be aware of these differences and provide the appropriate conversions where necessary. Proxies and gateways from MIME environments
1736            to HTTP also need to be aware of the differences because some conversions might be required.
1737         </p>
1738         <div id="mime-version">
1739            <div id="rfc.iref.m.1"></div>
1740            <div id="rfc.iref.h.9"></div>
1741            <h2 id="rfc.section.A.1"><a href="#rfc.section.A.1">A.1</a>&nbsp;<a href="#mime-version">MIME-Version</a></h2>
1742            <p id="rfc.section.A.1.p.1">HTTP is not a MIME-compliant protocol. However, HTTP/1.1 messages <em class="bcp14">MAY</em> include a single MIME-Version header field to indicate what version of the MIME protocol was used to construct the message.
1743               Use of the MIME-Version header field indicates that the message is in full compliance with the MIME protocol (as defined in <a href="#RFC2045" id="rfc.xref.RFC2045.2"><cite title="Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies">[RFC2045]</cite></a>). Proxies/gateways are responsible for ensuring full compliance (where possible) when exporting HTTP messages to strict MIME
1744               environments.
1745            </p>
1746            <div id="rfc.figure.u.29"></div><pre class="inline"><span id="rfc.iref.g.24"></span>  <a href="#mime-version" class="smpl">MIME-Version</a> = 1*<a href="#notation" class="smpl">DIGIT</a> "." 1*<a href="#notation" class="smpl">DIGIT</a>
1747</pre><p id="rfc.section.A.1.p.3">MIME version "1.0" is the default for use in HTTP/1.1. However, HTTP/1.1 message parsing and semantics are defined by this
1748               document and not the MIME specification.
1749            </p>
1750         </div>
1751         <div id="conversion.to.canonical.form">
1752            <h2 id="rfc.section.A.2"><a href="#rfc.section.A.2">A.2</a>&nbsp;<a href="#conversion.to.canonical.form">Conversion to Canonical Form</a></h2>
1753            <p id="rfc.section.A.2.p.1">MIME requires that an Internet mail body-part be converted to canonical form prior to being transferred, as described in <a href="https://tools.ietf.org/html/rfc2049#section-4">Section 4</a> of <a href="#RFC2049" id="rfc.xref.RFC2049.1"><cite title="Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples">[RFC2049]</cite></a>. <a href="#canonicalization.and.text.defaults" title="Canonicalization and Text Defaults">Section&nbsp;2.3.1</a> of this document describes the forms allowed for subtypes of the "text" media type when transmitted over HTTP. <a href="#RFC2046" id="rfc.xref.RFC2046.4"><cite title="Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">[RFC2046]</cite></a> requires that content with a type of "text" represent line breaks as CRLF and forbids the use of CR or LF outside of line
1754               break sequences. HTTP allows CRLF, bare CR, and bare LF to indicate a line break within text content when a message is transmitted
1755               over HTTP.
1756            </p>
1757            <p id="rfc.section.A.2.p.2">Where it is possible, a proxy or gateway from HTTP to a strict MIME environment <em class="bcp14">SHOULD</em> translate all line breaks within the text media types described in <a href="#canonicalization.and.text.defaults" title="Canonicalization and Text Defaults">Section&nbsp;2.3.1</a> of this document to the RFC 2049 canonical form of CRLF. Note, however, that this might be complicated by the presence of
1758               a Content-Encoding and by the fact that HTTP allows the use of some character encodings which do not use octets 13 and 10
1759               to represent CR and LF, respectively, as is the case for some multi-byte character encodings.
1760            </p>
1761            <p id="rfc.section.A.2.p.3">Conversion will break any cryptographic checksums applied to the original content unless the original content is already in
1762               canonical form. Therefore, the canonical form is recommended for any content that uses such checksums in HTTP.
1763            </p>
1764         </div>
1765         <div id="conversion.of.date.formats">
1766            <h2 id="rfc.section.A.3"><a href="#rfc.section.A.3">A.3</a>&nbsp;<a href="#conversion.of.date.formats">Conversion of Date Formats</a></h2>
1767            <p id="rfc.section.A.3.p.1">HTTP/1.1 uses a restricted set of date formats (<a href="p1-messaging.html#date.time.formats.full.date" title="Date/Time Formats: Full Date">Section 6.1</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>) to simplify the process of date comparison. Proxies and gateways from other protocols <em class="bcp14">SHOULD</em> ensure that any Date header field present in a message conforms to one of the HTTP/1.1 formats and rewrite the date if necessary.
1768            </p>
1769         </div>
1770         <div id="introduction.of.content-encoding">
1771            <h2 id="rfc.section.A.4"><a href="#rfc.section.A.4">A.4</a>&nbsp;<a href="#introduction.of.content-encoding">Introduction of Content-Encoding</a></h2>
1772            <p id="rfc.section.A.4.p.1">MIME does not include any concept equivalent to HTTP/1.1's Content-Encoding header field. Since this acts as a modifier on
1773               the media type, proxies and gateways from HTTP to MIME-compliant protocols <em class="bcp14">MUST</em> either change the value of the Content-Type header field or decode the representation before forwarding the message. (Some
1774               experimental applications of Content-Type for Internet mail have used a media-type parameter of ";conversions=&lt;content-coding&gt;"
1775               to perform a function equivalent to Content-Encoding. However, this parameter is not part of the MIME standards).
1776            </p>
1777         </div>
1778         <div id="no.content-transfer-encoding">
1779            <h2 id="rfc.section.A.5"><a href="#rfc.section.A.5">A.5</a>&nbsp;<a href="#no.content-transfer-encoding">No Content-Transfer-Encoding</a></h2>
1780            <p id="rfc.section.A.5.p.1">HTTP does not use the Content-Transfer-Encoding field of MIME. Proxies and gateways from MIME-compliant protocols to HTTP <em class="bcp14">MUST</em> remove any Content-Transfer-Encoding prior to delivering the response message to an HTTP client.
1781            </p>
1782            <p id="rfc.section.A.5.p.2">Proxies and gateways from HTTP to MIME-compliant protocols are responsible for ensuring that the message is in the correct
1783               format and encoding for safe transport on that protocol, where "safe transport" is defined by the limitations of the protocol
1784               being used. Such a proxy or gateway <em class="bcp14">SHOULD</em> label the data with an appropriate Content-Transfer-Encoding if doing so will improve the likelihood of safe transport over
1785               the destination protocol.
1786            </p>
1787         </div>
1788         <div id="introduction.of.transfer-encoding">
1789            <h2 id="rfc.section.A.6"><a href="#rfc.section.A.6">A.6</a>&nbsp;<a href="#introduction.of.transfer-encoding">Introduction of Transfer-Encoding</a></h2>
1790            <p id="rfc.section.A.6.p.1">HTTP/1.1 introduces the Transfer-Encoding header field (<a href="p1-messaging.html#header.transfer-encoding" title="Transfer-Encoding">Section 9.7</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>). Proxies/gateways <em class="bcp14">MUST</em> remove any transfer-coding prior to forwarding a message via a MIME-compliant protocol.
1791            </p>
1792         </div>
1793         <div id="mhtml.line.length">
1794            <h2 id="rfc.section.A.7"><a href="#rfc.section.A.7">A.7</a>&nbsp;<a href="#mhtml.line.length">MHTML and Line Length Limitations</a></h2>
1795            <p id="rfc.section.A.7.p.1">HTTP implementations which share code with MHTML <a href="#RFC2557" id="rfc.xref.RFC2557.2"><cite title="MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)">[RFC2557]</cite></a> implementations need to be aware of MIME line length limitations. Since HTTP does not have this limitation, HTTP does not
1796               fold long lines. MHTML messages being transported by HTTP follow all conventions of MHTML, including line length limitations
1797               and folding, canonicalization, etc., since HTTP transports all message-bodies as payload (see <a href="#multipart.types" title="Multipart Types">Section&nbsp;2.3.2</a>) and does not interpret the content or any MIME header lines that might be contained therein.
1798            </p>
1799         </div>
1800      </div>
1801      <div id="additional.features">
1802         <h1 id="rfc.section.B"><a href="#rfc.section.B">B.</a>&nbsp;<a href="#additional.features">Additional Features</a></h1>
1803         <p id="rfc.section.B.p.1"><a href="#RFC1945" id="rfc.xref.RFC1945.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.0">[RFC1945]</cite></a> and <a href="#RFC2068" id="rfc.xref.RFC2068.4"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2068]</cite></a> document protocol elements used by some existing HTTP implementations, but not consistently and correctly across most HTTP/1.1
1804            applications. Implementors are advised to be aware of these features, but cannot rely upon their presence in, or interoperability
1805            with, other HTTP/1.1 applications. Some of these describe proposed experimental features, and some describe features that
1806            experimental deployment found lacking that are now addressed in the base HTTP/1.1 specification.
1807         </p>
1808         <p id="rfc.section.B.p.2">A number of other header fields, such as Content-Disposition and Title, from SMTP and MIME are also often implemented (see <a href="#draft-ietf-httpbis-content-disp" id="rfc.xref.draft-ietf-httpbis-content-disp.1"><cite title="Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)">[draft-ietf-httpbis-content-disp]</cite></a> and <a href="#RFC2076" id="rfc.xref.RFC2076.1"><cite title="Common Internet Message Headers">[RFC2076]</cite></a>).
1809         </p>
1810      </div>
1811      <div id="changes.from.rfc.2616">
1812         <h1 id="rfc.section.C"><a href="#rfc.section.C">C.</a>&nbsp;<a href="#changes.from.rfc.2616">Changes from RFC 2616</a></h1>
1813         <p id="rfc.section.C.p.1">Clarify contexts that charset is used in. (<a href="#character.sets" title="Character Encodings (charset)">Section&nbsp;2.1</a>)
1814         </p>
1815         <p id="rfc.section.C.p.2">Remove the default character encoding for text media types; the default now is whatever the media type definition says. (<a href="#canonicalization.and.text.defaults" title="Canonicalization and Text Defaults">Section&nbsp;2.3.1</a>)
1816         </p>
1817         <p id="rfc.section.C.p.3">Change ABNF productions for header fields to only define the field value. (<a href="#header.fields" title="Header Field Definitions">Section&nbsp;6</a>)
1818         </p>
1819         <p id="rfc.section.C.p.4">Remove definition of Content-MD5 header field because it was inconsistently implemented with respect to partial responses,
1820            and also because of known deficiencies in the hash algorithm itself (see <a href="#RFC6151" id="rfc.xref.RFC6151.1"><cite title="Updated Security Considerations for the MD5 Message-Digest and the HMAC-MD5 Algorithms">[RFC6151]</cite></a> for details). (<a href="#header.fields" title="Header Field Definitions">Section&nbsp;6</a>)
1821         </p>
1822         <p id="rfc.section.C.p.5">Remove ISO-8859-1 special-casing in Accept-Charset. (<a href="#header.accept-charset" id="rfc.xref.header.accept-charset.3" title="Accept-Charset">Section&nbsp;6.2</a>)
1823         </p>
1824         <p id="rfc.section.C.p.6">Remove base URI setting semantics for Content-Location due to poor implementation support, which was caused by too many broken
1825            servers emitting bogus Content-Location header fields, and also the potentially undesirable effect of potentially breaking
1826            relative links in content-negotiated resources. (<a href="#header.content-location" id="rfc.xref.header.content-location.3" title="Content-Location">Section&nbsp;6.7</a>)
1827         </p>
1828         <p id="rfc.section.C.p.7">Remove discussion of Content-Disposition header field, it is now defined by <a href="#draft-ietf-httpbis-content-disp" id="rfc.xref.draft-ietf-httpbis-content-disp.2"><cite title="Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)">[draft-ietf-httpbis-content-disp]</cite></a>. (<a href="#additional.features" title="Additional Features">Appendix&nbsp;B</a>)
1829         </p>
1830         <p id="rfc.section.C.p.8">Remove reference to non-existant identity transfer-coding value tokens. (<a href="#no.content-transfer-encoding" title="No Content-Transfer-Encoding">Appendix&nbsp;A.5</a>)
1831         </p>
1832      </div>
1833      <div id="collected.abnf">
1834         <h1 id="rfc.section.D"><a href="#rfc.section.D">D.</a>&nbsp;<a href="#collected.abnf">Collected ABNF</a></h1>
1835         <div id="rfc.figure.u.30"></div><pre class="inline"><a href="#header.accept" class="smpl">Accept</a> = [ ( "," / ( media-range [ accept-params ] ) ) *( OWS "," [
1836 OWS ( media-range [ accept-params ] ) ] ) ]
1837<a href="#header.accept-charset" class="smpl">Accept-Charset</a> = *( "," OWS ) ( ( charset / "*" ) [ OWS ";" OWS "q="
1838 qvalue ] ) *( OWS "," [ OWS ( ( charset / "*" ) [ OWS ";" OWS "q="
1839 qvalue ] ) ] )
1840<a href="#header.accept-encoding" class="smpl">Accept-Encoding</a> = [ ( "," / ( codings [ OWS ";" OWS "q=" qvalue ] ) )
1841 *( OWS "," [ OWS ( codings [ OWS ";" OWS "q=" qvalue ] ) ] ) ]
1842<a href="#header.accept-language" class="smpl">Accept-Language</a> = *( "," OWS ) ( language-range [ OWS ";" OWS "q="
1843 qvalue ] ) *( OWS "," [ OWS ( language-range [ OWS ";" OWS "q="
1844 qvalue ] ) ] )
1845
1846<a href="#header.content-encoding" class="smpl">Content-Encoding</a> = *( "," OWS ) content-coding *( OWS "," [ OWS
1847 content-coding ] )
1848<a href="#header.content-language" class="smpl">Content-Language</a> = *( "," OWS ) language-tag *( OWS "," [ OWS
1849 language-tag ] )
1850<a href="#header.content-location" class="smpl">Content-Location</a> = absolute-URI / partial-URI
1851<a href="#header.content-type" class="smpl">Content-Type</a> = media-type
1852
1853<a href="#mime-version" class="smpl">MIME-Version</a> = 1*DIGIT "." 1*DIGIT
1854
1855<a href="#core.rules" class="smpl">OWS</a> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
1856
1857<a href="#abnf.dependencies" class="smpl">absolute-URI</a> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
1858<a href="#header.accept" class="smpl">accept-ext</a> = OWS ";" OWS token [ "=" word ]
1859<a href="#header.accept" class="smpl">accept-params</a> = OWS ";" OWS "q=" qvalue *accept-ext
1860<a href="#rule.parameter" class="smpl">attribute</a> = token
1861
1862<a href="#rule.charset" class="smpl">charset</a> = token
1863<a href="#header.accept-encoding" class="smpl">codings</a> = ( content-coding / "*" )
1864<a href="#content.codings" class="smpl">content-coding</a> = token
1865
1866<a href="#header.accept-language" class="smpl">language-range</a> = &lt;language-range, defined in [RFC4647], Section 2.1&gt;
1867<a href="#language.tags" class="smpl">language-tag</a> = &lt;Language-Tag, defined in [RFC5646], Section 2.1&gt;
1868
1869<a href="#header.accept" class="smpl">media-range</a> = ( "*/*" / ( type "/*" ) / ( type "/" subtype ) ) *( OWS
1870 ";" OWS parameter )
1871<a href="#media.types" class="smpl">media-type</a> = type "/" subtype *( OWS ";" OWS parameter )
1872
1873<a href="#rule.parameter" class="smpl">parameter</a> = attribute "=" value
1874<a href="#abnf.dependencies" class="smpl">partial-URI</a> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
1875
1876<a href="#abnf.dependencies" class="smpl">qvalue</a> = &lt;qvalue, defined in [Part1], Section 6.4&gt;
1877
1878<a href="#media.types" class="smpl">subtype</a> = token
1879
1880<a href="#core.rules" class="smpl">token</a> = &lt;token, defined in [Part1], Section 1.2.2&gt;
1881<a href="#media.types" class="smpl">type</a> = token
1882
1883<a href="#rule.parameter" class="smpl">value</a> = word
1884
1885<a href="#core.rules" class="smpl">word</a> = &lt;word, defined in [Part1], Section 1.2.2&gt;
1886</pre><div id="rfc.figure.u.31"></div>
1887         <p>ABNF diagnostics:</p><pre class="inline">; Accept defined but not used
1888; Accept-Charset defined but not used
1889; Accept-Encoding defined but not used
1890; Accept-Language defined but not used
1891; Content-Encoding defined but not used
1892; Content-Language defined but not used
1893; Content-Location defined but not used
1894; Content-Type defined but not used
1895; MIME-Version defined but not used
1896</pre></div>
1897      <div id="change.log">
1898         <h1 id="rfc.section.E"><a href="#rfc.section.E">E.</a>&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a></h1>
1899         <div>
1900            <h2 id="rfc.section.E.1"><a href="#rfc.section.E.1">E.1</a>&nbsp;Since RFC 2616
1901            </h2>
1902            <p id="rfc.section.E.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>.
1903            </p>
1904         </div>
1905         <div>
1906            <h2 id="rfc.section.E.2"><a href="#rfc.section.E.2">E.2</a>&nbsp;Since draft-ietf-httpbis-p3-payload-00
1907            </h2>
1908            <p id="rfc.section.E.2.p.1">Closed issues: </p>
1909            <ul>
1910               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/8">http://tools.ietf.org/wg/httpbis/trac/ticket/8</a>&gt;: "Media Type Registrations" (&lt;<a href="http://purl.org/NET/http-errata#media-reg">http://purl.org/NET/http-errata#media-reg</a>&gt;)
1911               </li>
1912               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/14">http://tools.ietf.org/wg/httpbis/trac/ticket/14</a>&gt;: "Clarification regarding quoting of charset values" (&lt;<a href="http://purl.org/NET/http-errata#charactersets">http://purl.org/NET/http-errata#charactersets</a>&gt;)
1913               </li>
1914               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/16">http://tools.ietf.org/wg/httpbis/trac/ticket/16</a>&gt;: "Remove 'identity' token references" (&lt;<a href="http://purl.org/NET/http-errata#identity">http://purl.org/NET/http-errata#identity</a>&gt;)
1915               </li>
1916               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/25">http://tools.ietf.org/wg/httpbis/trac/ticket/25</a>&gt;: "Accept-Encoding BNF"
1917               </li>
1918               <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"
1919               </li>
1920               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/46">http://tools.ietf.org/wg/httpbis/trac/ticket/46</a>&gt;: "RFC1700 references"
1921               </li>
1922               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/55">http://tools.ietf.org/wg/httpbis/trac/ticket/55</a>&gt;: "Updating to RFC4288"
1923               </li>
1924               <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"
1925               </li>
1926               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/66">http://tools.ietf.org/wg/httpbis/trac/ticket/66</a>&gt;: "ISO-8859-1 Reference"
1927               </li>
1928               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/68">http://tools.ietf.org/wg/httpbis/trac/ticket/68</a>&gt;: "Encoding References Normative"
1929               </li>
1930               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/86">http://tools.ietf.org/wg/httpbis/trac/ticket/86</a>&gt;: "Normative up-to-date references"
1931               </li>
1932            </ul>
1933         </div>
1934         <div>
1935            <h2 id="rfc.section.E.3"><a href="#rfc.section.E.3">E.3</a>&nbsp;Since draft-ietf-httpbis-p3-payload-01
1936            </h2>
1937            <p id="rfc.section.E.3.p.1">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;):
1938            </p>
1939            <ul>
1940               <li>Add explicit references to BNF syntax and rules imported from other parts of the specification.</li>
1941            </ul>
1942         </div>
1943         <div id="changes.since.02">
1944            <h2 id="rfc.section.E.4"><a href="#rfc.section.E.4">E.4</a>&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-p3-payload-02</a></h2>
1945            <p id="rfc.section.E.4.p.1">Closed issues: </p>
1946            <ul>
1947               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/67">http://tools.ietf.org/wg/httpbis/trac/ticket/67</a>&gt;: "Quoting Charsets"
1948               </li>
1949               <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"
1950               </li>
1951               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/115">http://tools.ietf.org/wg/httpbis/trac/ticket/115</a>&gt;: "missing default for qvalue in description of Accept-Encoding"
1952               </li>
1953            </ul>
1954            <p id="rfc.section.E.4.p.2">Ongoing work on IANA Message Header Field Registration (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/40">http://tools.ietf.org/wg/httpbis/trac/ticket/40</a>&gt;):
1955            </p>
1956            <ul>
1957               <li>Reference RFC 3984, and update header field registrations for headers defined in this document.</li>
1958            </ul>
1959         </div>
1960         <div id="changes.since.03">
1961            <h2 id="rfc.section.E.5"><a href="#rfc.section.E.5">E.5</a>&nbsp;<a href="#changes.since.03">Since draft-ietf-httpbis-p3-payload-03</a></h2>
1962            <p id="rfc.section.E.5.p.1">Closed issues: </p>
1963            <ul>
1964               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/67">http://tools.ietf.org/wg/httpbis/trac/ticket/67</a>&gt;: "Quoting Charsets"
1965               </li>
1966               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/113">http://tools.ietf.org/wg/httpbis/trac/ticket/113</a>&gt;: "language tag matching (Accept-Language) vs RFC4647"
1967               </li>
1968               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/121">http://tools.ietf.org/wg/httpbis/trac/ticket/121</a>&gt;: "RFC 1806 has been replaced by RFC2183"
1969               </li>
1970            </ul>
1971            <p id="rfc.section.E.5.p.2">Other changes: </p>
1972            <ul>
1973               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/68">http://tools.ietf.org/wg/httpbis/trac/ticket/68</a>&gt;: "Encoding References Normative" — rephrase the annotation and reference <a href="#BCP97" id="rfc.xref.BCP97.4"><cite title="Handling Normative References to Standards-Track Documents">[BCP97]</cite></a>.
1974               </li>
1975            </ul>
1976         </div>
1977         <div id="changes.since.04">
1978            <h2 id="rfc.section.E.6"><a href="#rfc.section.E.6">E.6</a>&nbsp;<a href="#changes.since.04">Since draft-ietf-httpbis-p3-payload-04</a></h2>
1979            <p id="rfc.section.E.6.p.1">Closed issues: </p>
1980            <ul>
1981               <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"
1982               </li>
1983            </ul>
1984            <p id="rfc.section.E.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;):
1985            </p>
1986            <ul>
1987               <li>Use "/" instead of "|" for alternatives.</li>
1988               <li>Introduce new ABNF rules for "bad" whitespace ("BWS"), optional whitespace ("OWS") and required whitespace ("RWS").</li>
1989               <li>Rewrite ABNFs to spell out whitespace rules, factor out header field value format definitions.</li>
1990            </ul>
1991         </div>
1992         <div id="changes.since.05">
1993            <h2 id="rfc.section.E.7"><a href="#rfc.section.E.7">E.7</a>&nbsp;<a href="#changes.since.05">Since draft-ietf-httpbis-p3-payload-05</a></h2>
1994            <p id="rfc.section.E.7.p.1">Closed issues: </p>
1995            <ul>
1996               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/118">http://tools.ietf.org/wg/httpbis/trac/ticket/118</a>&gt;: "Join "Differences Between HTTP Entities and RFC 2045 Entities"?"
1997               </li>
1998            </ul>
1999            <p id="rfc.section.E.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;):
2000            </p>
2001            <ul>
2002               <li>Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.</li>
2003            </ul>
2004            <p id="rfc.section.E.7.p.3">Other changes: </p>
2005            <ul>
2006               <li>Move definition of quality values into Part 1.</li>
2007            </ul>
2008         </div>
2009         <div id="changes.since.06">
2010            <h2 id="rfc.section.E.8"><a href="#rfc.section.E.8">E.8</a>&nbsp;<a href="#changes.since.06">Since draft-ietf-httpbis-p3-payload-06</a></h2>
2011            <p id="rfc.section.E.8.p.1">Closed issues: </p>
2012            <ul>
2013               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/80">http://tools.ietf.org/wg/httpbis/trac/ticket/80</a>&gt;: "Content-Location isn't special"
2014               </li>
2015               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/155">http://tools.ietf.org/wg/httpbis/trac/ticket/155</a>&gt;: "Content Sniffing"
2016               </li>
2017            </ul>
2018         </div>
2019         <div id="changes.since.07">
2020            <h2 id="rfc.section.E.9"><a href="#rfc.section.E.9">E.9</a>&nbsp;<a href="#changes.since.07">Since draft-ietf-httpbis-p3-payload-07</a></h2>
2021            <p id="rfc.section.E.9.p.1">Closed issues: </p>
2022            <ul>
2023               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/13">http://tools.ietf.org/wg/httpbis/trac/ticket/13</a>&gt;: "Updated reference for language tags"
2024               </li>
2025               <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"
2026               </li>
2027               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/154">http://tools.ietf.org/wg/httpbis/trac/ticket/154</a>&gt;: "Content-Location base-setting problems"
2028               </li>
2029               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/155">http://tools.ietf.org/wg/httpbis/trac/ticket/155</a>&gt;: "Content Sniffing"
2030               </li>
2031               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/188">http://tools.ietf.org/wg/httpbis/trac/ticket/188</a>&gt;: "pick IANA policy (RFC5226) for Transfer Coding / Content Coding"
2032               </li>
2033               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/189">http://tools.ietf.org/wg/httpbis/trac/ticket/189</a>&gt;: "move definitions of gzip/deflate/compress to part 1"
2034               </li>
2035            </ul>
2036            <p id="rfc.section.E.9.p.2">Partly resolved issues: </p>
2037            <ul>
2038               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/148">http://tools.ietf.org/wg/httpbis/trac/ticket/148</a>&gt;: "update IANA requirements wrt Transfer-Coding values" (add the IANA Considerations subsection)
2039               </li>
2040               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/149">http://tools.ietf.org/wg/httpbis/trac/ticket/149</a>&gt;: "update IANA requirements wrt Content-Coding values" (add the IANA Considerations subsection)
2041               </li>
2042            </ul>
2043         </div>
2044         <div id="changes.since.08">
2045            <h2 id="rfc.section.E.10"><a href="#rfc.section.E.10">E.10</a>&nbsp;<a href="#changes.since.08">Since draft-ietf-httpbis-p3-payload-08</a></h2>
2046            <p id="rfc.section.E.10.p.1">Closed issues: </p>
2047            <ul>
2048               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/81">http://tools.ietf.org/wg/httpbis/trac/ticket/81</a>&gt;: "Content Negotiation for media types"
2049               </li>
2050               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/181">http://tools.ietf.org/wg/httpbis/trac/ticket/181</a>&gt;: "Accept-Language: which RFC4647 filtering?"
2051               </li>
2052            </ul>
2053         </div>
2054         <div id="changes.since.09">
2055            <h2 id="rfc.section.E.11"><a href="#rfc.section.E.11">E.11</a>&nbsp;<a href="#changes.since.09">Since draft-ietf-httpbis-p3-payload-09</a></h2>
2056            <p id="rfc.section.E.11.p.1">Closed issues: </p>
2057            <ul>
2058               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/122">http://tools.ietf.org/wg/httpbis/trac/ticket/122</a>&gt;: "MIME-Version not listed in P1, general header fields"
2059               </li>
2060               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/143">http://tools.ietf.org/wg/httpbis/trac/ticket/143</a>&gt;: "IANA registry for content/transfer encodings"
2061               </li>
2062               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/155">http://tools.ietf.org/wg/httpbis/trac/ticket/155</a>&gt;: "Content Sniffing"
2063               </li>
2064               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/200">http://tools.ietf.org/wg/httpbis/trac/ticket/200</a>&gt;: "use of term "word" when talking about header structure"
2065               </li>
2066            </ul>
2067            <p id="rfc.section.E.11.p.2">Partly resolved issues: </p>
2068            <ul>
2069               <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"
2070               </li>
2071            </ul>
2072         </div>
2073         <div id="changes.since.10">
2074            <h2 id="rfc.section.E.12"><a href="#rfc.section.E.12">E.12</a>&nbsp;<a href="#changes.since.10">Since draft-ietf-httpbis-p3-payload-10</a></h2>
2075            <p id="rfc.section.E.12.p.1">Closed issues: </p>
2076            <ul>
2077               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/69">http://tools.ietf.org/wg/httpbis/trac/ticket/69</a>&gt;: "Clarify 'Requested Variant'"
2078               </li>
2079               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/80">http://tools.ietf.org/wg/httpbis/trac/ticket/80</a>&gt;: "Content-Location isn't special"
2080               </li>
2081               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/90">http://tools.ietf.org/wg/httpbis/trac/ticket/90</a>&gt;: "Delimiting messages with multipart/byteranges"
2082               </li>
2083               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/109">http://tools.ietf.org/wg/httpbis/trac/ticket/109</a>&gt;: "Clarify entity / representation / variant terminology"
2084               </li>
2085               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/136">http://tools.ietf.org/wg/httpbis/trac/ticket/136</a>&gt;: "confusing req. language for Content-Location"
2086               </li>
2087               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/167">http://tools.ietf.org/wg/httpbis/trac/ticket/167</a>&gt;: "Content-Location on 304 responses"
2088               </li>
2089               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/183">http://tools.ietf.org/wg/httpbis/trac/ticket/183</a>&gt;: "'requested resource' in content-encoding definition"
2090               </li>
2091               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/220">http://tools.ietf.org/wg/httpbis/trac/ticket/220</a>&gt;: "consider removing the 'changes from 2068' sections"
2092               </li>
2093            </ul>
2094            <p id="rfc.section.E.12.p.2">Partly resolved issues: </p>
2095            <ul>
2096               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/178">http://tools.ietf.org/wg/httpbis/trac/ticket/178</a>&gt;: "Content-MD5 and partial responses"
2097               </li>
2098            </ul>
2099         </div>
2100         <div id="changes.since.11">
2101            <h2 id="rfc.section.E.13"><a href="#rfc.section.E.13">E.13</a>&nbsp;<a href="#changes.since.11">Since draft-ietf-httpbis-p3-payload-11</a></h2>
2102            <p id="rfc.section.E.13.p.1">Closed issues: </p>
2103            <ul>
2104               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/123">http://tools.ietf.org/wg/httpbis/trac/ticket/123</a>&gt;: "Factor out Content-Disposition"
2105               </li>
2106            </ul>
2107         </div>
2108         <div id="changes.since.12">
2109            <h2 id="rfc.section.E.14"><a href="#rfc.section.E.14">E.14</a>&nbsp;<a href="#changes.since.12">Since draft-ietf-httpbis-p3-payload-12</a></h2>
2110            <p id="rfc.section.E.14.p.1">Closed issues: </p>
2111            <ul>
2112               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/224">http://tools.ietf.org/wg/httpbis/trac/ticket/224</a>&gt;: "Header Classification"
2113               </li>
2114               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/276">http://tools.ietf.org/wg/httpbis/trac/ticket/276</a>&gt;: "untangle ABNFs for header fields"
2115               </li>
2116               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/277">http://tools.ietf.org/wg/httpbis/trac/ticket/277</a>&gt;: "potentially misleading MAY in media-type def"
2117               </li>
2118            </ul>
2119         </div>
2120         <div id="changes.since.13">
2121            <h2 id="rfc.section.E.15"><a href="#rfc.section.E.15">E.15</a>&nbsp;<a href="#changes.since.13">Since draft-ietf-httpbis-p3-payload-13</a></h2>
2122            <p id="rfc.section.E.15.p.1">Closed issues: </p>
2123            <ul>
2124               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/20">http://tools.ietf.org/wg/httpbis/trac/ticket/20</a>&gt;: "Default charsets for text media types"
2125               </li>
2126               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/178">http://tools.ietf.org/wg/httpbis/trac/ticket/178</a>&gt;: "Content-MD5 and partial responses"
2127               </li>
2128               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/276">http://tools.ietf.org/wg/httpbis/trac/ticket/276</a>&gt;: "untangle ABNFs for header fields"
2129               </li>
2130               <li>&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/281">http://tools.ietf.org/wg/httpbis/trac/ticket/281</a>&gt;: "confusing undefined parameter in media range example"
2131               </li>
2132            </ul>
2133         </div>
2134      </div>
2135      <h1 id="rfc.index"><a href="#rfc.index">Index</a></h1>
2136      <p class="noprint"><a href="#rfc.index.A">A</a> <a href="#rfc.index.B">B</a> <a href="#rfc.index.C">C</a> <a href="#rfc.index.D">D</a> <a href="#rfc.index.G">G</a> <a href="#rfc.index.H">H</a> <a href="#rfc.index.I">I</a> <a href="#rfc.index.M">M</a> <a href="#rfc.index.P">P</a> <a href="#rfc.index.R">R</a>
2137      </p>
2138      <div class="print2col">
2139         <ul class="ind">
2140            <li><a id="rfc.index.A" href="#rfc.index.A"><b>A</b></a><ul>
2141                  <li>Accept header field&nbsp;&nbsp;<a href="#rfc.xref.header.accept.1">2.3</a>, <a href="#rfc.xref.header.accept.2">5.1</a>, <a href="#rfc.iref.a.1"><b>6.1</b></a>, <a href="#rfc.xref.header.accept.3">7.1</a></li>
2142                  <li>Accept-Charset header field&nbsp;&nbsp;<a href="#rfc.xref.header.accept-charset.1">5.1</a>, <a href="#rfc.iref.a.2"><b>6.2</b></a>, <a href="#rfc.xref.header.accept-charset.2">7.1</a>, <a href="#rfc.xref.header.accept-charset.3">C</a></li>
2143                  <li>Accept-Encoding header field&nbsp;&nbsp;<a href="#rfc.xref.header.accept-encoding.1">2.2</a>, <a href="#rfc.xref.header.accept-encoding.2">5.1</a>, <a href="#rfc.iref.a.3"><b>6.3</b></a>, <a href="#rfc.xref.header.accept-encoding.3">7.1</a></li>
2144                  <li>Accept-Language header field&nbsp;&nbsp;<a href="#rfc.xref.header.accept-language.1">5.1</a>, <a href="#rfc.iref.a.4"><b>6.4</b></a>, <a href="#rfc.xref.header.accept-language.2">7.1</a></li>
2145               </ul>
2146            </li>
2147            <li><a id="rfc.index.B" href="#rfc.index.B"><b>B</b></a><ul>
2148                  <li><em>BCP97</em>&nbsp;&nbsp;<a href="#rfc.xref.BCP97.1">10.1</a>, <a href="#rfc.xref.BCP97.2">10.1</a>, <a href="#rfc.xref.BCP97.3">10.1</a>, <a href="#BCP97"><b>10.2</b></a>, <a href="#rfc.xref.BCP97.4">E.5</a></li>
2149               </ul>
2150            </li>
2151            <li><a id="rfc.index.C" href="#rfc.index.C"><b>C</b></a><ul>
2152                  <li>Coding Format&nbsp;&nbsp;
2153                     <ul>
2154                        <li>compress&nbsp;&nbsp;<a href="#rfc.iref.c.3">2.2</a></li>
2155                        <li>deflate&nbsp;&nbsp;<a href="#rfc.iref.c.4">2.2</a></li>
2156                        <li>gzip&nbsp;&nbsp;<a href="#rfc.iref.c.5">2.2</a></li>
2157                        <li>identity&nbsp;&nbsp;<a href="#rfc.iref.c.6">2.2</a></li>
2158                     </ul>
2159                  </li>
2160                  <li>compress (Coding Format)&nbsp;&nbsp;<a href="#rfc.iref.c.2">2.2</a></li>
2161                  <li>content negotiation&nbsp;&nbsp;<a href="#rfc.iref.c.1">1.1</a></li>
2162                  <li>Content-Encoding header field&nbsp;&nbsp;<a href="#rfc.xref.header.content-encoding.1">2.2</a>, <a href="#rfc.xref.header.content-encoding.2">4.1</a>, <a href="#rfc.iref.c.7"><b>6.5</b></a>, <a href="#rfc.xref.header.content-encoding.3">6.5</a>, <a href="#rfc.xref.header.content-encoding.4">7.1</a></li>
2163                  <li>Content-Language header field&nbsp;&nbsp;<a href="#rfc.xref.header.content-language.1">4.1</a>, <a href="#rfc.iref.c.8"><b>6.6</b></a>, <a href="#rfc.xref.header.content-language.2">7.1</a></li>
2164                  <li>Content-Location header field&nbsp;&nbsp;<a href="#rfc.xref.header.content-location.1">4.1</a>, <a href="#rfc.iref.c.9"><b>6.7</b></a>, <a href="#rfc.xref.header.content-location.2">7.1</a>, <a href="#rfc.xref.header.content-location.3">C</a></li>
2165                  <li>Content-Type header field&nbsp;&nbsp;<a href="#rfc.xref.header.content-type.1">2.3</a>, <a href="#rfc.xref.header.content-type.2">4.1</a>, <a href="#rfc.iref.c.10"><b>6.8</b></a>, <a href="#rfc.xref.header.content-type.3">7.1</a></li>
2166               </ul>
2167            </li>
2168            <li><a id="rfc.index.D" href="#rfc.index.D"><b>D</b></a><ul>
2169                  <li>deflate (Coding Format)&nbsp;&nbsp;<a href="#rfc.iref.d.1">2.2</a></li>
2170                  <li><em>draft-ietf-httpbis-content-disp</em>&nbsp;&nbsp;<a href="#draft-ietf-httpbis-content-disp"><b>10.2</b></a>, <a href="#rfc.xref.draft-ietf-httpbis-content-disp.1">B</a>, <a href="#rfc.xref.draft-ietf-httpbis-content-disp.2">C</a></li>
2171               </ul>
2172            </li>
2173            <li><a id="rfc.index.G" href="#rfc.index.G"><b>G</b></a><ul>
2174                  <li><tt>Grammar</tt>&nbsp;&nbsp;
2175                     <ul>
2176                        <li><tt>Accept</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.11"><b>6.1</b></a></li>
2177                        <li><tt>Accept-Charset</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.15"><b>6.2</b></a></li>
2178                        <li><tt>Accept-Encoding</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.16"><b>6.3</b></a></li>
2179                        <li><tt>accept-ext</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.14"><b>6.1</b></a></li>
2180                        <li><tt>Accept-Language</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.18"><b>6.4</b></a></li>
2181                        <li><tt>accept-params</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.13"><b>6.1</b></a></li>
2182                        <li><tt>attribute</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.8"><b>2.3</b></a></li>
2183                        <li><tt>charset</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.1"><b>2.1</b></a></li>
2184                        <li><tt>codings</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.17"><b>6.3</b></a></li>
2185                        <li><tt>content-coding</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.2"><b>2.2</b></a></li>
2186                        <li><tt>Content-Encoding</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.20"><b>6.5</b></a></li>
2187                        <li><tt>Content-Language</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.21"><b>6.6</b></a></li>
2188                        <li><tt>Content-Location</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.22"><b>6.7</b></a></li>
2189                        <li><tt>Content-Type</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.23"><b>6.8</b></a></li>
2190                        <li><tt>language-range</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.19"><b>6.4</b></a></li>
2191                        <li><tt>language-tag</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.10"><b>2.4</b></a></li>
2192                        <li><tt>media-range</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.12"><b>6.1</b></a></li>
2193                        <li><tt>media-type</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.4"><b>2.3</b></a></li>
2194                        <li><tt>MIME-Version</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.24"><b>A.1</b></a></li>
2195                        <li><tt>parameter</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.7"><b>2.3</b></a></li>
2196                        <li><tt>subtype</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.6"><b>2.3</b></a></li>
2197                        <li><tt>type</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.5"><b>2.3</b></a></li>
2198                        <li><tt>value</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.9"><b>2.3</b></a></li>
2199                     </ul>
2200                  </li>
2201                  <li>gzip (Coding Format)&nbsp;&nbsp;<a href="#rfc.iref.g.3">2.2</a></li>
2202               </ul>
2203            </li>
2204            <li><a id="rfc.index.H" href="#rfc.index.H"><b>H</b></a><ul>
2205                  <li>Header Fields&nbsp;&nbsp;
2206                     <ul>
2207                        <li>Accept&nbsp;&nbsp;<a href="#rfc.xref.header.accept.1">2.3</a>, <a href="#rfc.xref.header.accept.2">5.1</a>, <a href="#rfc.iref.h.1"><b>6.1</b></a>, <a href="#rfc.xref.header.accept.3">7.1</a></li>
2208                        <li>Accept-Charset&nbsp;&nbsp;<a href="#rfc.xref.header.accept-charset.1">5.1</a>, <a href="#rfc.iref.h.2"><b>6.2</b></a>, <a href="#rfc.xref.header.accept-charset.2">7.1</a>, <a href="#rfc.xref.header.accept-charset.3">C</a></li>
2209                        <li>Accept-Encoding&nbsp;&nbsp;<a href="#rfc.xref.header.accept-encoding.1">2.2</a>, <a href="#rfc.xref.header.accept-encoding.2">5.1</a>, <a href="#rfc.iref.h.3"><b>6.3</b></a>, <a href="#rfc.xref.header.accept-encoding.3">7.1</a></li>
2210                        <li>Accept-Language&nbsp;&nbsp;<a href="#rfc.xref.header.accept-language.1">5.1</a>, <a href="#rfc.iref.h.4"><b>6.4</b></a>, <a href="#rfc.xref.header.accept-language.2">7.1</a></li>
2211                        <li>Content-Encoding&nbsp;&nbsp;<a href="#rfc.xref.header.content-encoding.1">2.2</a>, <a href="#rfc.xref.header.content-encoding.2">4.1</a>, <a href="#rfc.iref.h.5"><b>6.5</b></a>, <a href="#rfc.xref.header.content-encoding.3">6.5</a>, <a href="#rfc.xref.header.content-encoding.4">7.1</a></li>
2212                        <li>Content-Language&nbsp;&nbsp;<a href="#rfc.xref.header.content-language.1">4.1</a>, <a href="#rfc.iref.h.6"><b>6.6</b></a>, <a href="#rfc.xref.header.content-language.2">7.1</a></li>
2213                        <li>Content-Location&nbsp;&nbsp;<a href="#rfc.xref.header.content-location.1">4.1</a>, <a href="#rfc.iref.h.7"><b>6.7</b></a>, <a href="#rfc.xref.header.content-location.2">7.1</a>, <a href="#rfc.xref.header.content-location.3">C</a></li>
2214                        <li>Content-Type&nbsp;&nbsp;<a href="#rfc.xref.header.content-type.1">2.3</a>, <a href="#rfc.xref.header.content-type.2">4.1</a>, <a href="#rfc.iref.h.8"><b>6.8</b></a>, <a href="#rfc.xref.header.content-type.3">7.1</a></li>
2215                        <li>MIME-Version&nbsp;&nbsp;<a href="#rfc.xref.mime-version.1">7.1</a>, <a href="#rfc.iref.h.9"><b>A.1</b></a></li>
2216                     </ul>
2217                  </li>
2218               </ul>
2219            </li>
2220            <li><a id="rfc.index.I" href="#rfc.index.I"><b>I</b></a><ul>
2221                  <li>identity (Coding Format)&nbsp;&nbsp;<a href="#rfc.iref.i.1">2.2</a></li>
2222               </ul>
2223            </li>
2224            <li><a id="rfc.index.M" href="#rfc.index.M"><b>M</b></a><ul>
2225                  <li>MIME-Version header field&nbsp;&nbsp;<a href="#rfc.xref.mime-version.1">7.1</a>, <a href="#rfc.iref.m.1"><b>A.1</b></a></li>
2226               </ul>
2227            </li>
2228            <li><a id="rfc.index.P" href="#rfc.index.P"><b>P</b></a><ul>
2229                  <li><em>Part1</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.1">1.3</a>, <a href="#rfc.xref.Part1.2">1.3.1</a>, <a href="#rfc.xref.Part1.3">1.3.1</a>, <a href="#rfc.xref.Part1.4">1.3.1</a>, <a href="#rfc.xref.Part1.5">1.3.1</a>, <a href="#rfc.xref.Part1.6">1.3.2</a>, <a href="#rfc.xref.Part1.7">1.3.2</a>, <a href="#rfc.xref.Part1.8">1.3.2</a>, <a href="#rfc.xref.Part1.9">2.2</a>, <a href="#rfc.xref.Part1.10">2.2</a>, <a href="#rfc.xref.Part1.11">2.2</a>, <a href="#rfc.xref.Part1.12">2.2.1</a>, <a href="#rfc.xref.Part1.13">2.2.1</a>, <a href="#rfc.xref.Part1.14">3.1</a>, <a href="#rfc.xref.Part1.15">3.2</a>, <a href="#rfc.xref.Part1.16">6.1</a>, <a href="#rfc.xref.Part1.17">6.3</a>, <a href="#rfc.xref.Part1.18">6.7</a>, <a href="#rfc.xref.Part1.19">7.2</a>, <a href="#rfc.xref.Part1.20">7.2</a>, <a href="#rfc.xref.Part1.21">7.2</a>, <a href="#Part1"><b>10.1</b></a>, <a href="#rfc.xref.Part1.22">A.3</a>, <a href="#rfc.xref.Part1.23">A.6</a><ul>
2230                        <li><em>Section 1.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.1">1.3</a></li>
2231                        <li><em>Section 1.2.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.2">1.3.1</a>, <a href="#rfc.xref.Part1.3">1.3.1</a>, <a href="#rfc.xref.Part1.4">1.3.1</a>, <a href="#rfc.xref.Part1.5">1.3.1</a></li>
2232                        <li><em>Section 2.6</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.6">1.3.2</a>, <a href="#rfc.xref.Part1.7">1.3.2</a></li>
2233                        <li><em>Section 3.3</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.15">3.2</a></li>
2234                        <li><em>Section 4.3</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.18">6.7</a></li>
2235                        <li><em>Section 6.1</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.22">A.3</a></li>
2236                        <li><em>Section 6.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.12">2.2.1</a></li>
2237                        <li><em>Section 6.2.2.1</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.9">2.2</a>, <a href="#rfc.xref.Part1.19">7.2</a></li>
2238                        <li><em>Section 6.2.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.13">2.2.1</a></li>
2239                        <li><em>Section 6.2.2.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.10">2.2</a>, <a href="#rfc.xref.Part1.20">7.2</a></li>
2240                        <li><em>Section 6.2.2.3</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.11">2.2</a>, <a href="#rfc.xref.Part1.21">7.2</a></li>
2241                        <li><em>Section 6.4</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.8">1.3.2</a>, <a href="#rfc.xref.Part1.16">6.1</a>, <a href="#rfc.xref.Part1.17">6.3</a></li>
2242                        <li><em>Section 9.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.14">3.1</a></li>
2243                        <li><em>Section 9.7</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.23">A.6</a></li>
2244                     </ul>
2245                  </li>
2246                  <li><em>Part2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part2.1">5.1</a>, <a href="#Part2"><b>10.1</b></a><ul>
2247                        <li><em>Section 9.9</em>&nbsp;&nbsp;<a href="#rfc.xref.Part2.1">5.1</a></li>
2248                     </ul>
2249                  </li>
2250                  <li><em>Part4</em>&nbsp;&nbsp;<a href="#rfc.xref.Part4.1">4.1</a>, <a href="#Part4"><b>10.1</b></a><ul>
2251                        <li><em>Section 2.1</em>&nbsp;&nbsp;<a href="#rfc.xref.Part4.1">4.1</a></li>
2252                     </ul>
2253                  </li>
2254                  <li><em>Part5</em>&nbsp;&nbsp;<a href="#rfc.xref.Part5.1">3.1</a>, <a href="#Part5"><b>10.1</b></a><ul>
2255                        <li><em>Section 5.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part5.1">3.1</a></li>
2256                     </ul>
2257                  </li>
2258                  <li><em>Part6</em>&nbsp;&nbsp;<a href="#rfc.xref.Part6.1">4.1</a>, <a href="#rfc.xref.Part6.2">5.1</a>, <a href="#Part6"><b>10.1</b></a><ul>
2259                        <li><em>Section 3.3</em>&nbsp;&nbsp;<a href="#rfc.xref.Part6.1">4.1</a></li>
2260                        <li><em>Section 3.5</em>&nbsp;&nbsp;<a href="#rfc.xref.Part6.2">5.1</a></li>
2261                     </ul>
2262                  </li>
2263                  <li>payload&nbsp;&nbsp;<a href="#rfc.iref.p.1">3</a></li>
2264               </ul>
2265            </li>
2266            <li><a id="rfc.index.R" href="#rfc.index.R"><b>R</b></a><ul>
2267                  <li>representation&nbsp;&nbsp;<a href="#rfc.iref.r.1">4</a></li>
2268                  <li><em>RFC1945</em>&nbsp;&nbsp;<a href="#RFC1945"><b>10.2</b></a>, <a href="#rfc.xref.RFC1945.1">B</a></li>
2269                  <li><em>RFC1950</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC1950.1">7.2</a>, <a href="#RFC1950"><b>10.1</b></a></li>
2270                  <li><em>RFC1951</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC1951.1">7.2</a>, <a href="#RFC1951"><b>10.1</b></a></li>
2271                  <li><em>RFC1952</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC1952.1">7.2</a>, <a href="#RFC1952"><b>10.1</b></a></li>
2272                  <li><em>RFC2045</em>&nbsp;&nbsp;<a href="#RFC2045"><b>10.1</b></a>, <a href="#rfc.xref.RFC2045.1">A</a>, <a href="#rfc.xref.RFC2045.2">A.1</a></li>
2273                  <li><em>RFC2046</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2046.1">2.3</a>, <a href="#rfc.xref.RFC2046.2">2.3.2</a>, <a href="#rfc.xref.RFC2046.3">4.2</a>, <a href="#RFC2046"><b>10.1</b></a>, <a href="#rfc.xref.RFC2046.4">A.2</a><ul>
2274                        <li><em>Section 4.5.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2046.3">4.2</a></li>
2275                        <li><em>Section 5.1.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2046.2">2.3.2</a></li>
2276                     </ul>
2277                  </li>
2278                  <li><em>RFC2049</em>&nbsp;&nbsp;<a href="#RFC2049"><b>10.2</b></a>, <a href="#rfc.xref.RFC2049.1">A.2</a><ul>
2279                        <li><em>Section 4</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2049.1">A.2</a></li>
2280                     </ul>
2281                  </li>
2282                  <li><em>RFC2068</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2068.1">10.1</a>, <a href="#rfc.xref.RFC2068.2">10.1</a>, <a href="#rfc.xref.RFC2068.3">10.1</a>, <a href="#RFC2068"><b>10.2</b></a>, <a href="#rfc.xref.RFC2068.4">B</a></li>
2283                  <li><em>RFC2076</em>&nbsp;&nbsp;<a href="#RFC2076"><b>10.2</b></a>, <a href="#rfc.xref.RFC2076.1">B</a></li>
2284                  <li><em>RFC2119</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2119.1">1.2</a>, <a href="#RFC2119"><b>10.1</b></a></li>
2285                  <li><em>RFC2277</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2277.1">2.1</a>, <a href="#RFC2277"><b>10.2</b></a></li>
2286                  <li><em>RFC2295</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2295.1">5</a>, <a href="#RFC2295"><b>10.2</b></a></li>
2287                  <li><em>RFC2388</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2388.1">2.3.2</a>, <a href="#RFC2388"><b>10.2</b></a></li>
2288                  <li><em>RFC2557</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2557.1">6.7</a>, <a href="#RFC2557"><b>10.2</b></a>, <a href="#rfc.xref.RFC2557.2">A.7</a><ul>
2289                        <li><em>Section 4</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2557.1">6.7</a></li>
2290                     </ul>
2291                  </li>
2292                  <li><em>RFC2616</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.1">1</a>, <a href="#rfc.xref.RFC2616.2">6.4</a>, <a href="#RFC2616"><b>10.2</b></a>, <a href="#rfc.xref.RFC2616.3">E.1</a><ul>
2293                        <li><em>Section 14.4</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.2">6.4</a></li>
2294                     </ul>
2295                  </li>
2296                  <li><em>RFC3629</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC3629.1">2.1</a>, <a href="#RFC3629"><b>10.2</b></a></li>
2297                  <li><em>RFC3864</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC3864.1">7.1</a>, <a href="#RFC3864"><b>10.2</b></a></li>
2298                  <li><em>RFC4288</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC4288.1">2.3</a>, <a href="#RFC4288"><b>10.2</b></a></li>
2299                  <li><em>RFC4647</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC4647.1">6.4</a>, <a href="#rfc.xref.RFC4647.2">6.4</a>, <a href="#rfc.xref.RFC4647.3">6.4</a>, <a href="#rfc.xref.RFC4647.4">6.4</a>, <a href="#RFC4647"><b>10.1</b></a><ul>
2300                        <li><em>Section 2.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC4647.1">6.4</a></li>
2301                        <li><em>Section 2.3</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC4647.2">6.4</a></li>
2302                        <li><em>Section 3</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC4647.3">6.4</a></li>
2303                        <li><em>Section 3.3.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC4647.4">6.4</a></li>
2304                     </ul>
2305                  </li>
2306                  <li><em>RFC5226</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5226.1">2.2.1</a>, <a href="#RFC5226"><b>10.2</b></a><ul>
2307                        <li><em>Section 4.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5226.1">2.2.1</a></li>
2308                     </ul>
2309                  </li>
2310                  <li><em>RFC5234</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5234.1">1.3</a>, <a href="#rfc.xref.RFC5234.2">1.3</a>, <a href="#RFC5234"><b>10.1</b></a><ul>
2311                        <li><em>Appendix B.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5234.2">1.3</a></li>
2312                     </ul>
2313                  </li>
2314                  <li><em>RFC5322</em>&nbsp;&nbsp;<a href="#RFC5322"><b>10.2</b></a>, <a href="#rfc.xref.RFC5322.1">A</a></li>
2315                  <li><em>RFC5646</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5646.1">2.4</a>, <a href="#rfc.xref.RFC5646.2">2.4</a>, <a href="#rfc.xref.RFC5646.3">2.4</a>, <a href="#RFC5646"><b>10.1</b></a><ul>
2316                        <li><em>Section 2.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5646.2">2.4</a></li>
2317                     </ul>
2318                  </li>
2319                  <li><em>RFC6151</em>&nbsp;&nbsp;<a href="#RFC6151"><b>10.2</b></a>, <a href="#rfc.xref.RFC6151.1">C</a></li>
2320               </ul>
2321            </li>
2322         </ul>
2323      </div>
2324      <div class="avoidbreak">
2325         <h1 id="rfc.authors"><a href="#rfc.authors">Authors' Addresses</a></h1>
2326         <p><b>Roy T. Fielding</b>
2327            (editor)
2328            <br>Adobe Systems Incorporated<br>345 Park Ave<br>San Jose, CA&nbsp;95110<br>USA<br>Email: <a href="mailto:fielding@gbiv.com">fielding@gbiv.com</a><br>URI: <a href="http://roy.gbiv.com/">http://roy.gbiv.com/</a></p>
2329         <p><b>Jim Gettys</b><br>Alcatel-Lucent Bell Labs<br>21 Oak Knoll Road<br>Carlisle, MA&nbsp;01741<br>USA<br>Email: <a href="mailto:jg@freedesktop.org">jg@freedesktop.org</a><br>URI: <a href="http://gettys.wordpress.com/">http://gettys.wordpress.com/</a></p>
2330         <p><b>Jeffrey C. Mogul</b><br>Hewlett-Packard Company<br>HP Labs, Large Scale Systems Group<br>1501 Page Mill Road, MS 1177<br>Palo Alto, CA&nbsp;94304<br>USA<br>Email: <a href="mailto:JeffMogul@acm.org">JeffMogul@acm.org</a></p>
2331         <p><b>Henrik Frystyk Nielsen</b><br>Microsoft Corporation<br>1 Microsoft Way<br>Redmond, WA&nbsp;98052<br>USA<br>Email: <a href="mailto:henrikn@microsoft.com">henrikn@microsoft.com</a></p>
2332         <p><b>Larry Masinter</b><br>Adobe Systems Incorporated<br>345 Park Ave<br>San Jose, CA&nbsp;95110<br>USA<br>Email: <a href="mailto:LMM@acm.org">LMM@acm.org</a><br>URI: <a href="http://larry.masinter.net/">http://larry.masinter.net/</a></p>
2333         <p><b>Paul J. Leach</b><br>Microsoft Corporation<br>1 Microsoft Way<br>Redmond, WA&nbsp;98052<br>Email: <a href="mailto:paulle@microsoft.com">paulle@microsoft.com</a></p>
2334         <p><b>Tim Berners-Lee</b><br>World Wide Web Consortium<br>MIT Computer Science and Artificial Intelligence Laboratory<br>The Stata Center, Building 32<br>32 Vassar Street<br>Cambridge, MA&nbsp;02139<br>USA<br>Email: <a href="mailto:timbl@w3.org">timbl@w3.org</a><br>URI: <a href="http://www.w3.org/People/Berners-Lee/">http://www.w3.org/People/Berners-Lee/</a></p>
2335         <p><b>Yves Lafon</b>
2336            (editor)
2337            <br>World Wide Web Consortium<br>W3C / ERCIM<br>2004, rte des Lucioles<br>Sophia-Antipolis, AM&nbsp;06902<br>France<br>Email: <a href="mailto:ylafon@w3.org">ylafon@w3.org</a><br>URI: <a href="http://www.raubacapeu.net/people/yves/">http://www.raubacapeu.net/people/yves/</a></p>
2338         <p><b>Julian F. Reschke</b>
2339            (editor)
2340            <br>greenbytes GmbH<br>Hafenweg 16<br>Muenster, NW&nbsp;48155<br>Germany<br>Phone: <a href="tel:+492512807760">+49 251 2807760</a><br>Fax: <a href="fax:+492512807761">+49 251 2807761</a><br>Email: <a href="mailto:julian.reschke@greenbytes.de">julian.reschke@greenbytes.de</a><br>URI: <a href="http://greenbytes.de/tech/webdav/">http://greenbytes.de/tech/webdav/</a></p>
2341      </div>
2342   </body>
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