source: draft-ietf-httpbis/latest/p2-semantics.xml @ 280

Last change on this file since 280 was 280, checked in by julian.reschke@…, 12 years ago

Resolve #98: remove superfluous statement about request body handling for OPTIONS (closes #98).

  • Property svn:eol-style set to native
File size: 140.5 KB
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1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "July">
16  <!ENTITY ID-YEAR "2008">
17  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
18  <!ENTITY payload                    "<xref target='Part3' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY conditional                "<xref target='Part4' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY range                      "<xref target='Part5' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY caching                    "<xref target='Part6' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY auth                       "<xref target='Part7' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY content-negotiation        "<xref target='Part3' x:rel='#content.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY notation-abnf              "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY basic-rules                "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY general-syntax             "<xref target='Part1' x:rel='#general.syntax' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY uri                        "<xref target='Part1' x:rel='#uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY full-date                  "<xref target='Part1' x:rel='#full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY http-url                   "<xref target='Part1' x:rel='#http-url' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY http-version               "<xref target='Part1' x:rel='#http.version' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY use100                     "<xref target='Part1' x:rel='#use.of.the.100.status' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY qvalue                     "<xref target='Part3' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY header-accept              "<xref target='Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY header-accept-charset      "<xref target='Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35  <!ENTITY header-accept-encoding     "<xref target='Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY header-accept-language     "<xref target='Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY header-accept-ranges       "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY header-age                 "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY header-authorization       "<xref target='Part7' x:rel='#header.authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY header-cache-control       "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41  <!ENTITY header-content-location    "<xref target='Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
42  <!ENTITY header-content-range       "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
43  <!ENTITY header-etag                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
44  <!ENTITY header-expires             "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
45  <!ENTITY header-host                "<xref target='Part1' x:rel='#header.host' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
46  <!ENTITY header-if-match            "<xref target='Part4' x:rel='#header.if-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
47  <!ENTITY header-if-modified-since   "<xref target='Part4' x:rel='#header.if-modified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
48  <!ENTITY header-if-none-match       "<xref target='Part4' x:rel='#header.if-none-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
49  <!ENTITY header-if-range            "<xref target='Part5' x:rel='#header.if-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
50  <!ENTITY header-if-unmodified-since "<xref target='Part4' x:rel='#header.if-unmodified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
51  <!ENTITY header-pragma              "<xref target='Part6' x:rel='#header.pragma' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
52  <!ENTITY header-proxy-authenticate  "<xref target='Part7' x:rel='#header.proxy-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
53  <!ENTITY header-proxy-authorization "<xref target='Part7' x:rel='#header.proxy-authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
54  <!ENTITY header-range               "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
55  <!ENTITY header-upgrade             "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
56  <!ENTITY header-te                  "<xref target='Part1' x:rel='#header.upgrade' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
57  <!ENTITY header-vary                "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
58  <!ENTITY header-via                 "<xref target='Part1' x:rel='#header.via' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
59  <!ENTITY header-warning             "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
60  <!ENTITY header-www-authenticate    "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
61  <!ENTITY message-body               "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
62  <!ENTITY product-tokens             "<xref target='Part1' x:rel='#product.tokens' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
63  <!ENTITY media-type-message-http    "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
64]>
65<?rfc toc="yes" ?>
66<?rfc symrefs="yes" ?>
67<?rfc sortrefs="yes" ?>
68<?rfc compact="yes"?>
69<?rfc subcompact="no" ?>
70<?rfc linkmailto="no" ?>
71<?rfc editing="no" ?>
72<?rfc comments="yes"?>
73<?rfc inline="yes"?>
74<?rfc-ext allow-markup-in-artwork="yes" ?>
75<?rfc-ext include-references-in-index="yes" ?>
76<rfc obsoletes="2616" updates="2817" category="std"
77     ipr="full3978" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
78     xmlns:x='http://purl.org/net/xml2rfc/ext'>
79<front>
80
81  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
82
83  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
84    <organization abbrev="Day Software">Day Software</organization>
85    <address>
86      <postal>
87        <street>23 Corporate Plaza DR, Suite 280</street>
88        <city>Newport Beach</city>
89        <region>CA</region>
90        <code>92660</code>
91        <country>USA</country>
92      </postal>
93      <phone>+1-949-706-5300</phone>
94      <facsimile>+1-949-706-5305</facsimile>
95      <email>fielding@gbiv.com</email>
96      <uri>http://roy.gbiv.com/</uri>
97    </address>
98  </author>
99
100  <author initials="J." surname="Gettys" fullname="Jim Gettys">
101    <organization>One Laptop per Child</organization>
102    <address>
103      <postal>
104        <street>21 Oak Knoll Road</street>
105        <city>Carlisle</city>
106        <region>MA</region>
107        <code>01741</code>
108        <country>USA</country>
109      </postal>
110      <email>jg@laptop.org</email>
111      <uri>http://www.laptop.org/</uri>
112    </address>
113  </author>
114 
115  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
116    <organization abbrev="HP">Hewlett-Packard Company</organization>
117    <address>
118      <postal>
119        <street>HP Labs, Large Scale Systems Group</street>
120        <street>1501 Page Mill Road, MS 1177</street>
121        <city>Palo Alto</city>
122        <region>CA</region>
123        <code>94304</code>
124        <country>USA</country>
125      </postal>
126      <email>JeffMogul@acm.org</email>
127    </address>
128  </author>
129
130  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
131    <organization abbrev="Microsoft">Microsoft Corporation</organization>
132    <address>
133      <postal>
134        <street>1 Microsoft Way</street>
135        <city>Redmond</city>
136        <region>WA</region>
137        <code>98052</code>
138        <country>USA</country>
139      </postal>
140      <email>henrikn@microsoft.com</email>
141    </address>
142  </author>
143
144  <author initials="L." surname="Masinter" fullname="Larry Masinter">
145    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
146    <address>
147      <postal>
148        <street>345 Park Ave</street>
149        <city>San Jose</city>
150        <region>CA</region>
151        <code>95110</code>
152        <country>USA</country>
153      </postal>
154      <email>LMM@acm.org</email>
155      <uri>http://larry.masinter.net/</uri>
156    </address>
157  </author>
158 
159  <author initials="P." surname="Leach" fullname="Paul J. Leach">
160    <organization abbrev="Microsoft">Microsoft Corporation</organization>
161    <address>
162      <postal>
163        <street>1 Microsoft Way</street>
164        <city>Redmond</city>
165        <region>WA</region>
166        <code>98052</code>
167      </postal>
168      <email>paulle@microsoft.com</email>
169    </address>
170  </author>
171   
172  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
173    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
174    <address>
175      <postal>
176        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
177        <street>The Stata Center, Building 32</street>
178        <street>32 Vassar Street</street>
179        <city>Cambridge</city>
180        <region>MA</region>
181        <code>02139</code>
182        <country>USA</country>
183      </postal>
184      <email>timbl@w3.org</email>
185      <uri>http://www.w3.org/People/Berners-Lee/</uri>
186    </address>
187  </author>
188
189  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
190    <organization abbrev="W3C">World Wide Web Consortium</organization>
191    <address>
192      <postal>
193        <street>W3C / ERCIM</street>
194        <street>2004, rte des Lucioles</street>
195        <city>Sophia-Antipolis</city>
196        <region>AM</region>
197        <code>06902</code>
198        <country>France</country>
199      </postal>
200      <email>ylafon@w3.org</email>
201      <uri>http://www.raubacapeu.net/people/yves/</uri>
202    </address>
203  </author>
204
205  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
206    <organization abbrev="greenbytes">greenbytes GmbH</organization>
207    <address>
208      <postal>
209        <street>Hafenweg 16</street>
210        <city>Muenster</city><region>NW</region><code>48155</code>
211        <country>Germany</country>
212      </postal>
213      <phone>+49 251 2807760</phone>   
214      <facsimile>+49 251 2807761</facsimile>   
215      <email>julian.reschke@greenbytes.de</email>       
216      <uri>http://greenbytes.de/tech/webdav/</uri>     
217    </address>
218  </author>
219
220  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
221
222<abstract>
223<t>
224   The Hypertext Transfer Protocol (HTTP) is an application-level
225   protocol for distributed, collaborative, hypermedia information
226   systems. HTTP has been in use by the World Wide Web global information
227   initiative since 1990. This document is Part 2 of the seven-part specification
228   that defines the protocol referred to as "HTTP/1.1" and, taken together,
229   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
230   as expressed by request methods, request-header fields, response status codes,
231   and response-header fields.
232</t>
233</abstract>
234
235<note title="Editorial Note (To be removed by RFC Editor)">
236  <t>
237    Discussion of this draft should take place on the HTTPBIS working group
238    mailing list (ietf-http-wg@w3.org). The current issues list is
239    at <eref target="http://www.tools.ietf.org/wg/httpbis/trac/report/11"/>
240    and related documents (including fancy diffs) can be found at
241    <eref target="http://www.tools.ietf.org/wg/httpbis/"/>.
242  </t>
243  <t>
244    The changes in this draft are summarized in <xref target="changes.since.02"/>.
245  </t>
246</note>
247</front>
248<middle>
249<section title="Introduction" anchor="introduction">
250<t>
251   This document defines HTTP/1.1 request and response semantics.  Each HTTP
252   message, as defined in &messaging;, is in the form of either a request or
253   a response.  An HTTP server listens on a connection for HTTP requests and
254   responds to each request, in the order received on that connection, with
255   one or more HTTP response messages.  This document defines the commonly
256   agreed upon semantics of the HTTP uniform interface, the intentions defined
257   by each request method, and the various response messages that might be
258   expected as a result of applying that method for the requested resource.
259</t>
260<t>
261   This document is currently disorganized in order to minimize the changes
262   between drafts and enable reviewers to see the smaller errata changes.
263   The next draft will reorganize the sections to better reflect the content.
264   In particular, the sections will be ordered according to the typical
265   processing of an HTTP request message (after message parsing): resource
266   mapping, general header fields, methods, request modifiers, response
267   status, and resource metadata.  The current mess reflects how widely
268   dispersed these topics and associated requirements had become in
269   <xref target="RFC2616"/>.
270</t>
271
272<section title="Requirements" anchor="intro.requirements">
273<t>
274   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
275   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
276   document are to be interpreted as described in <xref target="RFC2119"/>.
277</t>
278<t>
279   An implementation is not compliant if it fails to satisfy one or more
280   of the &MUST; or &REQUIRED; level requirements for the protocols it
281   implements. An implementation that satisfies all the &MUST; or &REQUIRED;
282   level and all the &SHOULD; level requirements for its protocols is said
283   to be "unconditionally compliant"; one that satisfies all the &MUST;
284   level requirements but not all the &SHOULD; level requirements for its
285   protocols is said to be "conditionally compliant."
286</t>
287</section>
288</section>
289
290<section title="Notational Conventions and Generic Grammar" anchor="notation">
291  <x:anchor-alias value="comment"/>
292  <x:anchor-alias value="DIGIT"/>
293  <x:anchor-alias value="quoted-string"/>
294  <x:anchor-alias value="token"/>
295<t>
296  This specification uses the ABNF syntax defined in &notation-abnf; and
297  the core rules defined in &basic-rules;:
298  <cref anchor="abnf.dep">ABNF syntax and basic rules will be adopted from RFC 5234, see
299  <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>.</cref>
300</t>
301<figure><artwork type="abnf2616">
302  <x:ref>DIGIT</x:ref>         = &lt;DIGIT, defined in &basic-rules;&gt;
303</artwork></figure>
304<figure><artwork type="abnf2616">
305  <x:anchor-alias value="Accept"/>
306  <x:ref>comment</x:ref>       = &lt;comment, defined in &basic-rules;&gt;
307  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
308  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
309</artwork></figure>
310<t anchor="abnf.dependencies">
311  <x:anchor-alias value="absoluteURI"/>
312  <x:anchor-alias value="Accept"/>
313  <x:anchor-alias value="Accept-Charset"/>
314  <x:anchor-alias value="Accept-Encoding"/>
315  <x:anchor-alias value="Accept-Language"/>
316  <x:anchor-alias value="Accept-Ranges"/>
317  <x:anchor-alias value="Age"/>
318  <x:anchor-alias value="Authorization"/>
319  <x:anchor-alias value="ETag"/>
320  <x:anchor-alias value="fragment"/>
321  <x:anchor-alias value="Host"/>
322  <x:anchor-alias value="HTTP-date"/>
323  <x:anchor-alias value="If-Match"/>
324  <x:anchor-alias value="If-Modified-Since"/>
325  <x:anchor-alias value="If-None-Match"/>
326  <x:anchor-alias value="If-Range"/>
327  <x:anchor-alias value="If-Unmodified-Since"/>
328  <x:anchor-alias value="product"/>
329  <x:anchor-alias value="Proxy-Authenticate"/>
330  <x:anchor-alias value="Proxy-Authorization"/>
331  <x:anchor-alias value="Range"/>
332  <x:anchor-alias value="relativeURI"/>
333  <x:anchor-alias value="TE"/>
334  <x:anchor-alias value="Vary"/>
335  <x:anchor-alias value="WWW-Authenticate"/>
336  The ABNF rules below are defined in other parts:
337</t>
338<figure><!--Part1--><artwork type="abnf2616">
339  <x:ref>absoluteURI</x:ref>   = &lt;absoluteURI, defined in &general-syntax;&gt;
340  <x:ref>fragment</x:ref>      = &lt;fragment, defined in &general-syntax;&gt;
341  <x:ref>Host</x:ref>          = &lt;Host, defined in &header-host;&gt;
342  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
343  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
344  <x:ref>relativeURI</x:ref>   = &lt;relativeURI, defined in &general-syntax;&gt;
345  <x:ref>TE</x:ref>            = &lt;TE, defined in &header-te;&gt;
346</artwork></figure>
347<figure><!--Part3--><artwork type="abnf2616">
348  <x:ref>Accept</x:ref>        = &lt;Accept, defined in &header-accept;&gt;
349  <x:ref>Accept-Charset</x:ref> =
350             &lt;Accept-Charset, defined in &header-accept-charset;&gt;
351  <x:ref>Accept-Encoding</x:ref> =
352             &lt;Accept-Encoding, defined in &header-accept-encoding;&gt;
353  <x:ref>Accept-Language</x:ref> =
354             &lt;Accept-Language, defined in &header-accept-language;&gt;
355</artwork></figure>
356<figure><!--Part4--><artwork type="abnf2616">
357  <x:ref>ETag</x:ref>          = &lt;ETag, defined in &header-etag;&gt;
358  <x:ref>If-Match</x:ref>      = &lt;If-Match, defined in &header-if-match;&gt;
359  <x:ref>If-Modified-Since</x:ref> =
360             &lt;If-Modified-Since, defined in &header-if-modified-since;&gt;
361  <x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in &header-if-none-match;&gt;
362  <x:ref>If-Unmodified-Since</x:ref> =
363             &lt;If-Unmodified-Since, defined in &header-if-unmodified-since;&gt;
364</artwork></figure>
365<figure><!--Part5--><artwork type="abnf2616">
366  <x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in &header-accept-ranges;&gt;
367  <x:ref>If-Range</x:ref>      = &lt;If-Range, defined in &header-if-range;&gt;
368  <x:ref>Range</x:ref>         = &lt;Range, defined in &header-range;&gt;
369</artwork></figure>
370<figure><!--Part6--><artwork type="abnf2616">
371  <x:ref>Age</x:ref>           = &lt;Age, defined in &header-age;&gt;
372  <x:ref>Vary</x:ref>          = &lt;Vary, defined in &header-vary;&gt;
373</artwork><!--Part7--></figure>
374<figure><artwork type="abnf2616">
375  <x:ref>Authorization</x:ref> = &lt;Authorization, defined in &header-authorization;&gt;
376  <x:ref>Proxy-Authenticate</x:ref> =
377             &lt;Proxy-Authenticate, defined in &header-proxy-authenticate;&gt;
378  <x:ref>Proxy-Authorization</x:ref> =
379             &lt;Proxy-Authorization, defined in &header-proxy-authorization;&gt;
380  <x:ref>WWW-Authenticate</x:ref> =
381             &lt;WWW-Authenticate, defined in &header-www-authenticate;&gt;
382</artwork></figure>
383</section>
384
385<section title="Method" anchor="method">
386  <x:anchor-alias value="Method"/>
387  <x:anchor-alias value="extension-method"/>
388<t>
389   The Method  token indicates the method to be performed on the
390   resource identified by the Request-URI. The method is case-sensitive.
391</t>
392<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/><iref primary="true" item="Grammar" subitem="extension-method"/>
393  <x:ref>Method</x:ref>         = <x:abnf-char-sequence>"OPTIONS"</x:abnf-char-sequence>   ; "OPTIONS", <xref target="OPTIONS"/>
394                 | <x:abnf-char-sequence>"GET"</x:abnf-char-sequence>               ; "GET", <xref target="GET"/>
395                 | <x:abnf-char-sequence>"HEAD"</x:abnf-char-sequence>            ; "HEAD", <xref target="HEAD"/>
396                 | <x:abnf-char-sequence>"POST"</x:abnf-char-sequence>            ; "POST", <xref target="POST"/>
397                 | <x:abnf-char-sequence>"PUT"</x:abnf-char-sequence>               ; "PUT", <xref target="PUT"/>
398                 | <x:abnf-char-sequence>"DELETE"</x:abnf-char-sequence>      ; "DELETE", <xref target="DELETE"/>
399                 | <x:abnf-char-sequence>"TRACE"</x:abnf-char-sequence>         ; "TRACE", <xref target="TRACE"/>
400                 | <x:abnf-char-sequence>"CONNECT"</x:abnf-char-sequence>   ; "CONNECT", <xref target="CONNECT"/>
401                 | <x:ref>extension-method</x:ref>
402  <x:ref>extension-method</x:ref> = <x:ref>token</x:ref>
403</artwork></figure>
404<t>
405   The list of methods allowed by a resource can be specified in an
406   Allow header field (<xref target="header.allow"/>). The return code of the response
407   always notifies the client whether a method is currently allowed on a
408   resource, since the set of allowed methods can change dynamically. An
409   origin server &SHOULD; return the status code 405 (Method Not Allowed)
410   if the method is known by the origin server but not allowed for the
411   requested resource, and 501 (Not Implemented) if the method is
412   unrecognized or not implemented by the origin server. The methods GET
413   and HEAD &MUST; be supported by all general-purpose servers. All other
414   methods are &OPTIONAL;; however, if the above methods are implemented,
415   they &MUST; be implemented with the same semantics as those specified
416   in <xref target="method.definitions"/>.
417</t>
418
419<section title="Method Registry" anchor="method.registry">
420<t>
421  The HTTP Method Registry defines the name space for the Method token in the
422  Request line of an HTTP request.
423</t>
424<t>
425  Values to be added to this name space are subject to IETF review
426  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).  Any document registering
427  new method names should be traceable through statuses of either 'Obsoletes'
428  or 'Updates' to this document.
429</t>
430<t>
431  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
432</t>
433</section>
434</section>
435
436<section title="Request Header Fields" anchor="request.header.fields">
437  <x:anchor-alias value="extension-code"/>
438  <x:anchor-alias value="request-header"/>
439<t>
440   The request-header fields allow the client to pass additional
441   information about the request, and about the client itself, to the
442   server. These fields act as request modifiers, with semantics
443   equivalent to the parameters on a programming language method
444   invocation.
445</t>
446<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="request-header"/>
447  <x:ref>request-header</x:ref> = <x:ref>Accept</x:ref>                   ; &header-accept;
448                 | <x:ref>Accept-Charset</x:ref>           ; &header-accept-charset;
449                 | <x:ref>Accept-Encoding</x:ref>          ; &header-accept-encoding;
450                 | <x:ref>Accept-Language</x:ref>          ; &header-accept-language;
451                 | <x:ref>Authorization</x:ref>            ; &header-authorization;
452                 | <x:ref>Expect</x:ref>                   ; <xref target="header.expect"/>
453                 | <x:ref>From</x:ref>                     ; <xref target="header.from"/>
454                 | <x:ref>Host</x:ref>                     ; &header-host;
455                 | <x:ref>If-Match</x:ref>                 ; &header-if-match;
456                 | <x:ref>If-Modified-Since</x:ref>        ; &header-if-modified-since;
457                 | <x:ref>If-None-Match</x:ref>            ; &header-if-none-match;
458                 | <x:ref>If-Range</x:ref>                 ; &header-if-range;
459                 | <x:ref>If-Unmodified-Since</x:ref>      ; &header-if-unmodified-since;
460                 | <x:ref>Max-Forwards</x:ref>             ; <xref target="header.max-forwards"/>
461                 | <x:ref>Proxy-Authorization</x:ref>      ; &header-proxy-authorization;
462                 | <x:ref>Range</x:ref>                    ; &header-range;
463                 | <x:ref>Referer</x:ref>                  ; <xref target="header.referer"/>
464                 | <x:ref>TE</x:ref>                       ; &header-te;
465                 | <x:ref>User-Agent</x:ref>               ; <xref target="header.user-agent"/>
466</artwork></figure>
467<t>
468   Request-header field names can be extended reliably only in
469   combination with a change in the protocol version. However, new or
470   experimental header fields &MAY; be given the semantics of request-header
471   fields if all parties in the communication recognize them to
472   be request-header fields. Unrecognized header fields are treated as
473   entity-header fields.
474</t>
475</section>
476
477<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
478  <x:anchor-alias value="Reason-Phrase"/>
479  <x:anchor-alias value="Status-Code"/>
480<t>
481   The Status-Code element is a 3-digit integer result code of the
482   attempt to understand and satisfy the request. The status codes listed
483   below are defined in <xref target="status.codes"/>.
484   The Reason-Phrase is intended to give a short
485   textual description of the Status-Code. The Status-Code is intended
486   for use by automata and the Reason-Phrase is intended for the human
487   user. The client is not required to examine or display the Reason-Phrase.
488</t>
489<t> 
490   The individual values of the numeric status codes defined for
491   HTTP/1.1, and an example set of corresponding Reason-Phrase's, are
492   presented below. The reason phrases listed here are only
493   recommendations -- they &MAY; be replaced by local equivalents without
494   affecting the protocol.
495</t>
496<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Status-Code"/><iref primary="true" item="Grammar" subitem="extension-code"/><iref primary="true" item="Grammar" subitem="Reason-Phrase"/>
497  <x:ref>Status-Code</x:ref>    =
498         "100"  ; <xref target="status.100"/>: Continue
499       | "101"  ; <xref target="status.101"/>: Switching Protocols
500       | "200"  ; <xref target="status.200"/>: OK
501       | "201"  ; <xref target="status.201"/>: Created
502       | "202"  ; <xref target="status.202"/>: Accepted
503       | "203"  ; <xref target="status.203"/>: Non-Authoritative Information
504       | "204"  ; <xref target="status.204"/>: No Content
505       | "205"  ; <xref target="status.205"/>: Reset Content
506       | "206"  ; <xref target="status.206"/>: Partial Content
507       | "300"  ; <xref target="status.300"/>: Multiple Choices
508       | "301"  ; <xref target="status.301"/>: Moved Permanently
509       | "302"  ; <xref target="status.302"/>: Found
510       | "303"  ; <xref target="status.303"/>: See Other
511       | "304"  ; <xref target="status.304"/>: Not Modified
512       | "305"  ; <xref target="status.305"/>: Use Proxy
513       | "307"  ; <xref target="status.307"/>: Temporary Redirect
514       | "400"  ; <xref target="status.400"/>: Bad Request
515       | "401"  ; <xref target="status.401"/>: Unauthorized
516       | "402"  ; <xref target="status.402"/>: Payment Required
517       | "403"  ; <xref target="status.403"/>: Forbidden
518       | "404"  ; <xref target="status.404"/>: Not Found
519       | "405"  ; <xref target="status.405"/>: Method Not Allowed
520       | "406"  ; <xref target="status.406"/>: Not Acceptable
521       | "407"  ; <xref target="status.407"/>: Proxy Authentication Required
522       | "408"  ; <xref target="status.408"/>: Request Time-out
523       | "409"  ; <xref target="status.409"/>: Conflict
524       | "410"  ; <xref target="status.410"/>: Gone
525       | "411"  ; <xref target="status.411"/>: Length Required
526       | "412"  ; <xref target="status.412"/>: Precondition Failed
527       | "413"  ; <xref target="status.413"/>: Request Entity Too Large
528       | "414"  ; <xref target="status.414"/>: Request-URI Too Large
529       | "415"  ; <xref target="status.415"/>: Unsupported Media Type
530       | "416"  ; <xref target="status.416"/>: Requested range not satisfiable
531       | "417"  ; <xref target="status.417"/>: Expectation Failed
532       | "500"  ; <xref target="status.500"/>: Internal Server Error
533       | "501"  ; <xref target="status.501"/>: Not Implemented
534       | "502"  ; <xref target="status.502"/>: Bad Gateway
535       | "503"  ; <xref target="status.503"/>: Service Unavailable
536       | "504"  ; <xref target="status.504"/>: Gateway Time-out
537       | "505"  ; <xref target="status.505"/>: HTTP Version not supported
538       | <x:ref>extension-code</x:ref>
539
540  <x:ref>extension-code</x:ref> = 3<x:ref>DIGIT</x:ref>
541  <x:ref>Reason-Phrase</x:ref>  = *&lt;<x:ref>TEXT</x:ref>, excluding <x:ref>CR</x:ref>, <x:ref>LF</x:ref>&gt;
542</artwork></figure>
543<t>
544   HTTP status codes are extensible. HTTP applications are not required
545   to understand the meaning of all registered status codes, though such
546   understanding is obviously desirable. However, applications &MUST;
547   understand the class of any status code, as indicated by the first
548   digit, and treat any unrecognized response as being equivalent to the
549   x00 status code of that class, with the exception that an
550   unrecognized response &MUST-NOT; be cached. For example, if an
551   unrecognized status code of 431 is received by the client, it can
552   safely assume that there was something wrong with its request and
553   treat the response as if it had received a 400 status code. In such
554   cases, user agents &SHOULD; present to the user the entity returned
555   with the response, since that entity is likely to include human-readable
556   information which will explain the unusual status.
557</t>
558
559<section title="Status Code Registry" anchor="status.code.registry">
560<t>
561  The HTTP Status Code Registry defines the name space for the Status-Code
562  token in the Status line of an HTTP response.
563</t>
564<t>
565  Values to be added to this name space are subject to IETF review
566  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).  Any document registering
567  new status codes should be traceable through statuses of either 'Obsoletes'
568  or 'Updates' to this document.
569</t>
570<t>
571  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
572</t>
573</section>
574
575</section>
576
577<section title="Response Header Fields" anchor="response.header.fields">
578  <x:anchor-alias value="response-header"/>
579<t>
580   The response-header fields allow the server to pass additional
581   information about the response which cannot be placed in the Status-Line.
582   These header fields give information about the server and about
583   further access to the resource identified by the Request-URI.
584</t>
585<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="response-header"/>
586  <x:ref>response-header</x:ref> = <x:ref>Accept-Ranges</x:ref>           ; &header-accept-ranges;
587                  | <x:ref>Age</x:ref>                     ; &header-age;
588                  | <x:ref>Allow</x:ref>                   ; <xref target="header.allow"/>
589                  | <x:ref>ETag</x:ref>                    ; &header-etag;
590                  | <x:ref>Location</x:ref>                ; <xref target="header.location"/>
591                  | <x:ref>Proxy-Authenticate</x:ref>      ; &header-proxy-authenticate;
592                  | <x:ref>Retry-After</x:ref>             ; <xref target="header.retry-after"/>
593                  | <x:ref>Server</x:ref>                  ; <xref target="header.server"/>
594                  | <x:ref>Vary</x:ref>                    ; &header-vary;
595                  | <x:ref>WWW-Authenticate</x:ref>        ; &header-www-authenticate;
596</artwork></figure>
597<t>
598   Response-header field names can be extended reliably only in
599   combination with a change in the protocol version. However, new or
600   experimental header fields &MAY; be given the semantics of response-header
601   fields if all parties in the communication recognize them to
602   be response-header fields. Unrecognized header fields are treated as
603   entity-header fields.
604</t>
605</section>
606
607<section title="Entity" anchor="entity">
608<t>
609   Request and Response messages &MAY; transfer an entity if not otherwise
610   restricted by the request method or response status code. An entity
611   consists of entity-header fields and an entity-body, although some
612   responses will only include the entity-headers. HTTP entity-body and
613   entity-header fields are defined in &payload;.
614</t>
615<t>
616   An entity-body is only present in a message when a message-body is
617   present, as described in &message-body;. The entity-body is obtained
618   from the message-body by decoding any Transfer-Encoding that might
619   have been applied to ensure safe and proper transfer of the message.
620</t>
621</section>
622
623
624<section title="Method Definitions" anchor="method.definitions">
625<t>
626   The set of common methods for HTTP/1.1 is defined below. Although
627   this set can be expanded, additional methods cannot be assumed to
628   share the same semantics for separately extended clients and servers.
629</t>
630
631<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
632
633<section title="Safe Methods" anchor="safe.methods">
634<t>
635   Implementors should be aware that the software represents the user in
636   their interactions over the Internet, and should be careful to allow
637   the user to be aware of any actions they might take which may have an
638   unexpected significance to themselves or others.
639</t>
640<t>
641   In particular, the convention has been established that the GET and
642   HEAD methods &SHOULD-NOT;  have the significance of taking an action
643   other than retrieval. These methods ought to be considered "safe".
644   This allows user agents to represent other methods, such as POST, PUT
645   and DELETE, in a special way, so that the user is made aware of the
646   fact that a possibly unsafe action is being requested.
647</t>
648<t>
649   Naturally, it is not possible to ensure that the server does not
650   generate side-effects as a result of performing a GET request; in
651   fact, some dynamic resources consider that a feature. The important
652   distinction here is that the user did not request the side-effects,
653   so therefore cannot be held accountable for them.
654</t>
655</section>
656
657<section title="Idempotent Methods" anchor="idempotent.methods">
658<t>
659   Methods can also have the property of "idempotence" in that (aside
660   from error or expiration issues) the side-effects of N &gt; 0 identical
661   requests is the same as for a single request. The methods GET, HEAD,
662   PUT and DELETE share this property. Also, the methods OPTIONS and
663   TRACE &SHOULD-NOT;  have side effects, and so are inherently idempotent.
664</t>
665<t>
666   However, it is possible that a sequence of several requests is non-idempotent,
667   even if all of the methods executed in that sequence are
668   idempotent. (A sequence is idempotent if a single execution of the
669   entire sequence always yields a result that is not changed by a
670   reexecution of all, or part, of that sequence.) For example, a
671   sequence is non-idempotent if its result depends on a value that is
672   later modified in the same sequence.
673</t>
674<t>
675   A sequence that never has side effects is idempotent, by definition
676   (provided that no concurrent operations are being executed on the
677   same set of resources).
678</t>
679</section>
680</section>
681
682<section title="OPTIONS" anchor="OPTIONS">
683  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
684  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
685<t>
686   The OPTIONS method represents a request for information about the
687   communication options available on the request/response chain
688   identified by the Request-URI. This method allows the client to
689   determine the options and/or requirements associated with a resource,
690   or the capabilities of a server, without implying a resource action
691   or initiating a resource retrieval.
692</t>
693<t>
694   Responses to this method are not cacheable.
695</t>
696<t>
697   If the OPTIONS request includes an entity-body (as indicated by the
698   presence of Content-Length or Transfer-Encoding), then the media type
699   &MUST; be indicated by a Content-Type field. Although this
700   specification does not define any use for such a body, future
701   extensions to HTTP might use the OPTIONS body to make more detailed
702   queries on the server.
703</t>
704<t>
705   If the Request-URI is an asterisk ("*"), the OPTIONS request is
706   intended to apply to the server in general rather than to a specific
707   resource. Since a server's communication options typically depend on
708   the resource, the "*" request is only useful as a "ping" or "no-op"
709   type of method; it does nothing beyond allowing the client to test
710   the capabilities of the server. For example, this can be used to test
711   a proxy for HTTP/1.1 compliance (or lack thereof).
712</t>
713<t>
714   If the Request-URI is not an asterisk, the OPTIONS request applies
715   only to the options that are available when communicating with that
716   resource.
717</t>
718<t>
719   A 200 response &SHOULD; include any header fields that indicate
720   optional features implemented by the server and applicable to that
721   resource (e.g., Allow), possibly including extensions not defined by
722   this specification. The response body, if any, &SHOULD; also include
723   information about the communication options. The format for such a
724   body is not defined by this specification, but might be defined by
725   future extensions to HTTP. Content negotiation &MAY; be used to select
726   the appropriate response format. If no response body is included, the
727   response &MUST; include a Content-Length field with a field-value of
728   "0".
729</t>
730<t>
731   The Max-Forwards request-header field &MAY; be used to target a
732   specific proxy in the request chain. When a proxy receives an OPTIONS
733   request on an absoluteURI for which request forwarding is permitted,
734   the proxy &MUST; check for a Max-Forwards field. If the Max-Forwards
735   field-value is zero ("0"), the proxy &MUST-NOT; forward the message;
736   instead, the proxy &SHOULD; respond with its own communication options.
737   If the Max-Forwards field-value is an integer greater than zero, the
738   proxy &MUST; decrement the field-value when it forwards the request. If
739   no Max-Forwards field is present in the request, then the forwarded
740   request &MUST-NOT; include a Max-Forwards field.
741</t>
742</section>
743
744<section title="GET" anchor="GET">
745  <iref primary="true" item="GET method" x:for-anchor=""/>
746  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
747<t>
748   The GET method means retrieve whatever information (in the form of an
749   entity) is identified by the Request-URI. If the Request-URI refers
750   to a data-producing process, it is the produced data which shall be
751   returned as the entity in the response and not the source text of the
752   process, unless that text happens to be the output of the process.
753</t>
754<t>
755   The semantics of the GET method change to a "conditional GET" if the
756   request message includes an If-Modified-Since, If-Unmodified-Since,
757   If-Match, If-None-Match, or If-Range header field. A conditional GET
758   method requests that the entity be transferred only under the
759   circumstances described by the conditional header field(s). The
760   conditional GET method is intended to reduce unnecessary network
761   usage by allowing cached entities to be refreshed without requiring
762   multiple requests or transferring data already held by the client.
763</t>
764<t>
765   The semantics of the GET method change to a "partial GET" if the
766   request message includes a Range header field. A partial GET requests
767   that only part of the entity be transferred, as described in &header-range;.
768   The partial GET method is intended to reduce unnecessary
769   network usage by allowing partially-retrieved entities to be
770   completed without transferring data already held by the client.
771</t>
772<t>
773   The response to a GET request is cacheable if and only if it meets
774   the requirements for HTTP caching described in &caching;.
775</t>
776<t>
777   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
778</t>
779</section>
780
781<section title="HEAD" anchor="HEAD">
782  <iref primary="true" item="HEAD method" x:for-anchor=""/>
783  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
784<t>
785   The HEAD method is identical to GET except that the server &MUST-NOT;
786   return a message-body in the response. The metainformation contained
787   in the HTTP headers in response to a HEAD request &SHOULD; be identical
788   to the information sent in response to a GET request. This method can
789   be used for obtaining metainformation about the entity implied by the
790   request without transferring the entity-body itself. This method is
791   often used for testing hypertext links for validity, accessibility,
792   and recent modification.
793</t>
794<t>
795   The response to a HEAD request &MAY; be cacheable in the sense that the
796   information contained in the response &MAY; be used to update a
797   previously cached entity from that resource. If the new field values
798   indicate that the cached entity differs from the current entity (as
799   would be indicated by a change in Content-Length, Content-MD5, ETag
800   or Last-Modified), then the cache &MUST; treat the cache entry as
801   stale.
802</t>
803</section>
804
805<section title="POST" anchor="POST">
806  <iref primary="true" item="POST method" x:for-anchor=""/>
807  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
808<t>
809   The POST method is used to request that the origin server accept the
810   entity enclosed in the request as data to be processed by the resource
811   identified by the Request-URI in the Request-Line. POST is designed
812   to allow a uniform method to cover the following functions:
813  <list style="symbols">
814    <t>
815      Annotation of existing resources;
816    </t>
817    <t>
818        Posting a message to a bulletin board, newsgroup, mailing list,
819        or similar group of articles;
820    </t>
821    <t>
822        Providing a block of data, such as the result of submitting a
823        form, to a data-handling process;
824    </t>
825    <t>
826        Extending a database through an append operation.
827    </t>
828  </list>
829</t>
830<t>
831   The actual function performed by the POST method is determined by the
832   server and is usually dependent on the Request-URI.
833</t>
834<t>
835   The action performed by the POST method might not result in a
836   resource that can be identified by a URI. In this case, either 200
837   (OK) or 204 (No Content) is the appropriate response status,
838   depending on whether or not the response includes an entity that
839   describes the result.
840</t>
841<t>
842   If a resource has been created on the origin server, the response
843   &SHOULD; be 201 (Created) and contain an entity which describes the
844   status of the request and refers to the new resource, and a Location
845   header (see <xref target="header.location"/>).
846</t>
847<t>
848   Responses to this method are not cacheable, unless the response
849   includes appropriate Cache-Control or Expires header fields. However,
850   the 303 (See Other) response can be used to direct the user agent to
851   retrieve a cacheable resource.
852</t>
853</section>
854
855<section title="PUT" anchor="PUT">
856  <iref primary="true" item="PUT method" x:for-anchor=""/>
857  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
858<t>
859   The PUT method requests that the enclosed entity be stored at the
860   supplied Request-URI. If the Request-URI refers to an already
861   existing resource, the enclosed entity &SHOULD; be considered as a
862   modified version of the one residing on the origin server. If the
863   Request-URI does not point to an existing resource, and that URI is
864   capable of being defined as a new resource by the requesting user
865   agent, the origin server can create the resource with that URI. If a
866   new resource is created at the Request-URI, the origin server &MUST;
867         inform the user agent
868   via the 201 (Created) response. If an existing resource is modified,
869   either the 200 (OK) or 204 (No Content) response codes &SHOULD; be sent
870   to indicate successful completion of the request. If the resource
871   could not be created or modified with the Request-URI, an appropriate
872   error response &SHOULD; be given that reflects the nature of the
873   problem. The recipient of the entity &MUST-NOT; ignore any Content-*
874   (e.g. Content-Range) headers that it does not understand or implement
875   and &MUST; return a 501 (Not Implemented) response in such cases.
876</t>
877<t>
878   If the request passes through a cache and the Request-URI identifies
879   one or more currently cached entities, those entries &SHOULD; be
880   treated as stale. Responses to this method are not cacheable.
881</t>
882<t>
883   The fundamental difference between the POST and PUT requests is
884   reflected in the different meaning of the Request-URI. The URI in a
885   POST request identifies the resource that will handle the enclosed
886   entity. That resource might be a data-accepting process, a gateway to
887   some other protocol, or a separate entity that accepts annotations.
888   In contrast, the URI in a PUT request identifies the entity enclosed
889   with the request -- the user agent knows what URI is intended and the
890   server &MUST-NOT; attempt to apply the request to some other resource.
891   If the server desires that the request be applied to a different URI,
892   it &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
893   then make its own decision regarding whether or not to redirect the
894   request.
895</t>
896<t>
897   A single resource &MAY; be identified by many different URIs. For
898   example, an article might have a URI for identifying "the current
899   version" which is separate from the URI identifying each particular
900   version. In this case, a PUT request on a general URI might result in
901   several other URIs being defined by the origin server.
902</t>
903<t>
904   HTTP/1.1 does not define how a PUT method affects the state of an
905   origin server.
906</t>
907<t>
908   Unless otherwise specified for a particular entity-header, the
909   entity-headers in the PUT request &SHOULD; be applied to the resource
910   created or modified by the PUT.
911</t>
912</section>
913
914<section title="DELETE" anchor="DELETE">
915  <iref primary="true" item="DELETE method" x:for-anchor=""/>
916  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
917<t>
918   The DELETE method requests that the origin server delete the resource
919   identified by the Request-URI. This method &MAY; be overridden by human
920   intervention (or other means) on the origin server. The client cannot
921   be guaranteed that the operation has been carried out, even if the
922   status code returned from the origin server indicates that the action
923   has been completed successfully. However, the server &SHOULD-NOT; 
924   indicate success unless, at the time the response is given, it
925   intends to delete the resource or move it to an inaccessible
926   location.
927</t>
928<t>
929   A successful response &SHOULD; be 200 (OK) if the response includes an
930   entity describing the status, 202 (Accepted) if the action has not
931   yet been enacted, or 204 (No Content) if the action has been enacted
932   but the response does not include an entity.
933</t>
934<t>
935   If the request passes through a cache and the Request-URI identifies
936   one or more currently cached entities, those entries &SHOULD; be
937   treated as stale. Responses to this method are not cacheable.
938</t>
939</section>
940
941<section title="TRACE" anchor="TRACE">
942  <iref primary="true" item="TRACE method" x:for-anchor=""/>
943  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
944<t>
945   The TRACE method is used to invoke a remote, application-layer loop-back
946   of the request message. The final recipient of the request
947   &SHOULD; reflect the message received back to the client as the
948   entity-body of a 200 (OK) response. The final recipient is either the
949   origin server or the first proxy or gateway to receive a Max-Forwards
950   value of zero (0) in the request (see <xref target="header.max-forwards"/>). A TRACE request
951   &MUST-NOT; include an entity.
952</t>
953<t>
954   TRACE allows the client to see what is being received at the other
955   end of the request chain and use that data for testing or diagnostic
956   information. The value of the Via header field (&header-via;) is of
957   particular interest, since it acts as a trace of the request chain.
958   Use of the Max-Forwards header field allows the client to limit the
959   length of the request chain, which is useful for testing a chain of
960   proxies forwarding messages in an infinite loop.
961</t>
962<t>
963   If the request is valid, the response &SHOULD; contain the entire
964   request message in the entity-body, with a Content-Type of
965   "message/http" (see &media-type-message-http;). Responses to this method
966   &MUST-NOT; be cached.
967</t>
968</section>
969
970<section title="CONNECT" anchor="CONNECT">
971  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
972  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
973<t>
974   This specification reserves the method name CONNECT for use with a
975   proxy that can dynamically switch to being a tunnel (e.g. SSL
976   tunneling <xref target="RFC2817"/>).
977</t>
978</section>
979</section>
980
981
982<section title="Status Code Definitions" anchor="status.codes">
983<t>
984   Each Status-Code is described below, including a description of which
985   method(s) it can follow and any metainformation required in the
986   response.
987</t>
988
989<section title="Informational 1xx" anchor="status.1xx">
990<t>
991   This class of status code indicates a provisional response,
992   consisting only of the Status-Line and optional headers, and is
993   terminated by an empty line. There are no required headers for this
994   class of status code. Since HTTP/1.0 did not define any 1xx status
995   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
996   except under experimental conditions.
997</t>
998<t>
999   A client &MUST; be prepared to accept one or more 1xx status responses
1000   prior to a regular response, even if the client does not expect a 100
1001   (Continue) status message. Unexpected 1xx status responses &MAY; be
1002   ignored by a user agent.
1003</t>
1004<t>
1005   Proxies &MUST; forward 1xx responses, unless the connection between the
1006   proxy and its client has been closed, or unless the proxy itself
1007   requested the generation of the 1xx response. (For example, if a
1008   proxy adds a "Expect: 100-continue" field when it forwards a request,
1009   then it need not forward the corresponding 100 (Continue)
1010   response(s).)
1011</t>
1012
1013<section title="100 Continue" anchor="status.100">
1014  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1015  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1016<t>
1017   The client &SHOULD; continue with its request. This interim response is
1018   used to inform the client that the initial part of the request has
1019   been received and has not yet been rejected by the server. The client
1020   &SHOULD; continue by sending the remainder of the request or, if the
1021   request has already been completed, ignore this response. The server
1022   &MUST; send a final response after the request has been completed. See
1023   &use100; for detailed discussion of the use and handling of this
1024   status code.
1025</t>
1026</section>
1027
1028<section title="101 Switching Protocols" anchor="status.101">
1029  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1030  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1031<t>
1032   The server understands and is willing to comply with the client's
1033   request, via the Upgrade message header field (&header-upgrade;), for a
1034   change in the application protocol being used on this connection. The
1035   server will switch protocols to those defined by the response's
1036   Upgrade header field immediately after the empty line which
1037   terminates the 101 response.
1038</t>
1039<t>
1040   The protocol &SHOULD; be switched only when it is advantageous to do
1041   so. For example, switching to a newer version of HTTP is advantageous
1042   over older versions, and switching to a real-time, synchronous
1043   protocol might be advantageous when delivering resources that use
1044   such features.
1045</t>
1046</section>
1047</section>
1048
1049<section title="Successful 2xx" anchor="status.2xx">
1050<t>
1051   This class of status code indicates that the client's request was
1052   successfully received, understood, and accepted.
1053</t>
1054
1055<section title="200 OK" anchor="status.200">
1056  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1057  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1058<t>
1059   The request has succeeded. The information returned with the response
1060   is dependent on the method used in the request, for example:
1061  <list style="hanging">
1062    <t hangText="GET">
1063          an entity corresponding to the requested resource is sent in
1064          the response;
1065    </t>
1066    <t hangText="HEAD">
1067          the entity-header fields corresponding to the requested
1068          resource are sent in the response without any message-body;
1069    </t>
1070    <t hangText="POST">
1071      an entity describing or containing the result of the action;
1072    </t>
1073    <t hangText="TRACE">
1074      an entity containing the request message as received by the
1075      end server.
1076    </t>
1077  </list>
1078</t>
1079</section>
1080
1081<section title="201 Created" anchor="status.201">
1082  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1083  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1084<t>
1085   The request has been fulfilled and resulted in a new resource being
1086   created. The newly created resource can be referenced by the URI(s)
1087   returned in the entity of the response, with the most specific URI
1088   for the resource given by a Location header field. The response
1089   &SHOULD; include an entity containing a list of resource
1090   characteristics and location(s) from which the user or user agent can
1091   choose the one most appropriate. The entity format is specified by
1092   the media type given in the Content-Type header field. The origin
1093   server &MUST; create the resource before returning the 201 status code.
1094   If the action cannot be carried out immediately, the server &SHOULD;
1095   respond with 202 (Accepted) response instead.
1096</t>
1097<t>
1098   A 201 response &MAY; contain an ETag response header field indicating
1099   the current value of the entity tag for the requested variant just
1100   created, see &header-etag;.
1101</t>
1102</section>
1103
1104<section title="202 Accepted" anchor="status.202">
1105  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1106  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1107<t>
1108   The request has been accepted for processing, but the processing has
1109   not been completed.  The request might or might not eventually be
1110   acted upon, as it might be disallowed when processing actually takes
1111   place. There is no facility for re-sending a status code from an
1112   asynchronous operation such as this.
1113</t>
1114<t>
1115   The 202 response is intentionally non-committal. Its purpose is to
1116   allow a server to accept a request for some other process (perhaps a
1117   batch-oriented process that is only run once per day) without
1118   requiring that the user agent's connection to the server persist
1119   until the process is completed. The entity returned with this
1120   response &SHOULD; include an indication of the request's current status
1121   and either a pointer to a status monitor or some estimate of when the
1122   user can expect the request to be fulfilled.
1123</t>
1124</section>
1125
1126<section title="203 Non-Authoritative Information" anchor="status.203">
1127  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1128  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1129<t>
1130   The returned metainformation in the entity-header is not the
1131   definitive set as available from the origin server, but is gathered
1132   from a local or a third-party copy. The set presented &MAY; be a subset
1133   or superset of the original version. For example, including local
1134   annotation information about the resource might result in a superset
1135   of the metainformation known by the origin server. Use of this
1136   response code is not required and is only appropriate when the
1137   response would otherwise be 200 (OK).
1138</t>
1139</section>
1140
1141<section title="204 No Content" anchor="status.204">
1142  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1143  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1144<t>
1145   The server has fulfilled the request but does not need to return an
1146   entity-body, and might want to return updated metainformation. The
1147   response &MAY; include new or updated metainformation in the form of
1148   entity-headers, which if present &SHOULD; be associated with the
1149   requested variant.
1150</t>
1151<t>
1152   If the client is a user agent, it &SHOULD-NOT;  change its document view
1153   from that which caused the request to be sent. This response is
1154   primarily intended to allow input for actions to take place without
1155   causing a change to the user agent's active document view, although
1156   any new or updated metainformation &SHOULD; be applied to the document
1157   currently in the user agent's active view.
1158</t>
1159<t>
1160   The 204 response &MUST-NOT; include a message-body, and thus is always
1161   terminated by the first empty line after the header fields.
1162</t>
1163</section>
1164
1165<section title="205 Reset Content" anchor="status.205">
1166  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1167  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1168<t>
1169   The server has fulfilled the request and the user agent &SHOULD; reset
1170   the document view which caused the request to be sent. This response
1171   is primarily intended to allow input for actions to take place via
1172   user input, followed by a clearing of the form in which the input is
1173   given so that the user can easily initiate another input action. The
1174   response &MUST-NOT; include an entity.
1175</t>
1176</section>
1177
1178<section title="206 Partial Content" anchor="status.206">
1179  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1180  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1181<t>
1182   The server has fulfilled the partial GET request for the resource
1183   and the enclosed entity is a partial representation as defined in &range;.
1184</t>
1185</section>
1186</section>
1187
1188<section title="Redirection 3xx" anchor="status.3xx">
1189<t>
1190   This class of status code indicates that further action needs to be
1191   taken by the user agent in order to fulfill the request.  The action
1192   required &MAY; be carried out by the user agent without interaction
1193   with the user if and only if the method used in the second request is
1194   GET or HEAD. A client &SHOULD; detect infinite redirection loops, since
1195   such loops generate network traffic for each redirection.
1196  <list><t>
1197      <x:h>Note:</x:h> previous versions of this specification recommended a
1198      maximum of five redirections. Content developers should be aware
1199      that there might be clients that implement such a fixed
1200      limitation.
1201  </t></list>
1202</t>
1203
1204<section title="300 Multiple Choices" anchor="status.300">
1205  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1206  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1207<t>
1208   The requested resource corresponds to any one of a set of
1209   representations, each with its own specific location, and agent-driven
1210   negotiation information (&content-negotiation;) is being provided so that
1211   the user (or user agent) can select a preferred representation and
1212   redirect its request to that location.
1213</t>
1214<t>
1215   Unless it was a HEAD request, the response &SHOULD; include an entity
1216   containing a list of resource characteristics and location(s) from
1217   which the user or user agent can choose the one most appropriate. The
1218   entity format is specified by the media type given in the Content-Type
1219   header field. Depending upon the format and the capabilities of
1220   the user agent, selection of the most appropriate choice &MAY; be
1221   performed automatically. However, this specification does not define
1222   any standard for such automatic selection.
1223</t>
1224<t>
1225   If the server has a preferred choice of representation, it &SHOULD;
1226   include the specific URI for that representation in the Location
1227   field; user agents &MAY; use the Location field value for automatic
1228   redirection. This response is cacheable unless indicated otherwise.
1229</t>
1230</section>
1231
1232<section title="301 Moved Permanently" anchor="status.301">
1233  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1234  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1235<t>
1236   The requested resource has been assigned a new permanent URI and any
1237   future references to this resource &SHOULD; use one of the returned
1238   URIs.  Clients with link editing capabilities ought to automatically
1239   re-link references to the Request-URI to one or more of the new
1240   references returned by the server, where possible. This response is
1241   cacheable unless indicated otherwise.
1242</t>
1243<t>
1244   The new permanent URI &SHOULD; be given by the Location field in the
1245   response. Unless the request method was HEAD, the entity of the
1246   response &SHOULD; contain a short hypertext note with a hyperlink to
1247   the new URI(s).
1248</t>
1249<t>
1250   If the 301 status code is received in response to a request method
1251   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1252   then the request &MAY; be automatically redirected by the user agent without
1253   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1254   request unless it can be confirmed by the user, since this might
1255   change the conditions under which the request was issued.
1256  <list><t>
1257      <x:h>Note:</x:h> When automatically redirecting a POST request after
1258      receiving a 301 status code, some existing HTTP/1.0 user agents
1259      will erroneously change it into a GET request.
1260  </t></list>
1261</t>
1262</section>
1263
1264<section title="302 Found" anchor="status.302">
1265  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1266  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1267<t>
1268   The requested resource resides temporarily under a different URI.
1269   Since the redirection might be altered on occasion, the client &SHOULD;
1270   continue to use the Request-URI for future requests.  This response
1271   is only cacheable if indicated by a Cache-Control or Expires header
1272   field.
1273</t>
1274<t>
1275   The temporary URI &SHOULD; be given by the Location field in the
1276   response. Unless the request method was HEAD, the entity of the
1277   response &SHOULD; contain a short hypertext note with a hyperlink to
1278   the new URI(s).
1279</t>
1280<t>
1281   If the 302 status code is received in response to a request method
1282   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1283   then the request &MAY; be automatically redirected by the user agent without
1284   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1285   request unless it can be confirmed by the user, since this might
1286   change the conditions under which the request was issued.
1287  <list><t>
1288      <x:h>Note:</x:h> <xref target="RFC1945"/> and <xref target="RFC2068"/> specify that the client is not allowed
1289      to change the method on the redirected request.  However, most
1290      existing user agent implementations treat 302 as if it were a 303
1291      response, performing a GET on the Location field-value regardless
1292      of the original request method. The status codes 303 and 307 have
1293      been added for servers that wish to make unambiguously clear which
1294      kind of reaction is expected of the client.
1295  </t></list>
1296</t>
1297</section>
1298
1299<section title="303 See Other" anchor="status.303">
1300  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1301  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1302<t>
1303   The server directs the user agent to a different resource, indicated
1304   by a URI in the Location header field, that provides an indirect
1305   response to the original request.  The user agent &MAY; perform a GET
1306   request on the URI in the Location field in order to obtain a
1307   representation corresponding to the response, be redirected again,
1308   or end with an error status.  The Location URI is not a substitute
1309   reference for the originally requested resource.
1310</t>
1311<t>
1312   The 303 status is generally applicable to any HTTP method.  It is
1313   primarily used to allow the output of a POST action to redirect
1314   the user agent to a selected resource, since doing so provides the
1315   information corresponding to the POST response in a form that
1316   can be separately identified, bookmarked, and cached independent
1317   of the original request.
1318</t>
1319<t>
1320   A 303 response to a GET request indicates that the requested
1321   resource does not have a representation of its own that can be
1322   transferred by the server over HTTP.  The Location URI indicates a
1323   resource that is descriptive of the requested resource such that
1324   the follow-on representation may be useful without implying that
1325   it adequately represents the previously requested resource.
1326   Note that answers to the questions of what can be represented, what
1327   representations are adequate, and what might be a useful description
1328   are outside the scope of HTTP and thus entirely determined by the
1329   resource owner(s).
1330</t>
1331<t>
1332   A 303 response &SHOULD-NOT; be cached unless it is indicated as
1333   cacheable by Cache-Control or Expires header fields.  Except for
1334   responses to a HEAD request, the entity of a 303 response &SHOULD;
1335   contain a short hypertext note with a hyperlink to the Location URI.
1336</t>
1337</section>
1338
1339<section title="304 Not Modified" anchor="status.304">
1340  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1341  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1342<t>
1343   The response to the request has not been modified since the conditions
1344   indicated by the client's conditional GET request, as defined in &conditional;.
1345</t>
1346</section>
1347
1348<section title="305 Use Proxy" anchor="status.305">
1349  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1350  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1351<t>
1352   The 305 status was defined in a previous version of this specification
1353   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1354</t>
1355</section>
1356
1357<section title="306 (Unused)" anchor="status.306">
1358  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1359  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1360<t>
1361   The 306 status code was used in a previous version of the
1362   specification, is no longer used, and the code is reserved.
1363</t>
1364</section>
1365
1366<section title="307 Temporary Redirect" anchor="status.307">
1367  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1368  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1369<t>
1370   The requested resource resides temporarily under a different URI.
1371   Since the redirection &MAY; be altered on occasion, the client &SHOULD;
1372   continue to use the Request-URI for future requests.  This response
1373   is only cacheable if indicated by a Cache-Control or Expires header
1374   field.
1375</t>
1376<t>
1377   The temporary URI &SHOULD; be given by the Location field in the
1378   response. Unless the request method was HEAD, the entity of the
1379   response &SHOULD; contain a short hypertext note with a hyperlink to
1380   the new URI(s) , since many pre-HTTP/1.1 user agents do not
1381   understand the 307 status. Therefore, the note &SHOULD; contain the
1382   information necessary for a user to repeat the original request on
1383   the new URI.
1384</t>
1385<t>
1386   If the 307 status code is received in response to a request method
1387   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1388   then the request &MAY; be automatically redirected by the user agent without
1389   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1390   request unless it can be confirmed by the user, since this might
1391   change the conditions under which the request was issued.
1392</t>
1393</section>
1394</section>
1395
1396<section title="Client Error 4xx" anchor="status.4xx">
1397<t>
1398   The 4xx class of status code is intended for cases in which the
1399   client seems to have erred. Except when responding to a HEAD request,
1400   the server &SHOULD; include an entity containing an explanation of the
1401   error situation, and whether it is a temporary or permanent
1402   condition. These status codes are applicable to any request method.
1403   User agents &SHOULD; display any included entity to the user.
1404</t>
1405<t>
1406   If the client is sending data, a server implementation using TCP
1407   &SHOULD; be careful to ensure that the client acknowledges receipt of
1408   the packet(s) containing the response, before the server closes the
1409   input connection. If the client continues sending data to the server
1410   after the close, the server's TCP stack will send a reset packet to
1411   the client, which may erase the client's unacknowledged input buffers
1412   before they can be read and interpreted by the HTTP application.
1413</t>
1414
1415<section title="400 Bad Request" anchor="status.400">
1416  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1417  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1418<t>
1419   The request could not be understood by the server due to malformed
1420   syntax. The client &SHOULD-NOT;  repeat the request without
1421   modifications.
1422</t>
1423</section>
1424
1425<section title="401 Unauthorized" anchor="status.401">
1426  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1427  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1428<t>
1429   The request requires user authentication (see &auth;).
1430</t>
1431</section>
1432
1433<section title="402 Payment Required" anchor="status.402">
1434  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1435  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1436<t>
1437   This code is reserved for future use.
1438</t>
1439</section>
1440
1441<section title="403 Forbidden" anchor="status.403">
1442  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1443  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1444<t>
1445   The server understood the request, but is refusing to fulfill it.
1446   Authorization will not help and the request &SHOULD-NOT;  be repeated.
1447   If the request method was not HEAD and the server wishes to make
1448   public why the request has not been fulfilled, it &SHOULD; describe the
1449   reason for the refusal in the entity.  If the server does not wish to
1450   make this information available to the client, the status code 404
1451   (Not Found) can be used instead.
1452</t>
1453</section>
1454
1455<section title="404 Not Found" anchor="status.404">
1456  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1457  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1458<t>
1459   The server has not found anything matching the Request-URI. No
1460   indication is given of whether the condition is temporary or
1461   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1462   knows, through some internally configurable mechanism, that an old
1463   resource is permanently unavailable and has no forwarding address.
1464   This status code is commonly used when the server does not wish to
1465   reveal exactly why the request has been refused, or when no other
1466   response is applicable.
1467</t>
1468</section>
1469
1470<section title="405 Method Not Allowed" anchor="status.405">
1471  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1472  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1473<t>
1474   The method specified in the Request-Line is not allowed for the
1475   resource identified by the Request-URI. The response &MUST; include an
1476   Allow header containing a list of valid methods for the requested
1477   resource.
1478</t>
1479</section>
1480
1481<section title="406 Not Acceptable" anchor="status.406">
1482  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1483  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1484<t>
1485   The resource identified by the request is only capable of generating
1486   response entities which have content characteristics not acceptable
1487   according to the accept headers sent in the request.
1488</t>
1489<t>
1490   Unless it was a HEAD request, the response &SHOULD; include an entity
1491   containing a list of available entity characteristics and location(s)
1492   from which the user or user agent can choose the one most
1493   appropriate. The entity format is specified by the media type given
1494   in the Content-Type header field. Depending upon the format and the
1495   capabilities of the user agent, selection of the most appropriate
1496   choice &MAY; be performed automatically. However, this specification
1497   does not define any standard for such automatic selection.
1498  <list><t>
1499      <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1500      not acceptable according to the accept headers sent in the
1501      request. In some cases, this may even be preferable to sending a
1502      406 response. User agents are encouraged to inspect the headers of
1503      an incoming response to determine if it is acceptable.
1504  </t></list>
1505</t>
1506<t>
1507   If the response could be unacceptable, a user agent &SHOULD;
1508   temporarily stop receipt of more data and query the user for a
1509   decision on further actions.
1510</t>
1511</section>
1512
1513<section title="407 Proxy Authentication Required" anchor="status.407">
1514  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1515  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1516<t>
1517   This code is similar to 401 (Unauthorized), but indicates that the
1518   client must first authenticate itself with the proxy (see &auth;).
1519</t>
1520</section>
1521
1522<section title="408 Request Timeout" anchor="status.408">
1523  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1524  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1525<t>
1526   The client did not produce a request within the time that the server
1527   was prepared to wait. The client &MAY; repeat the request without
1528   modifications at any later time.
1529</t>
1530</section>
1531
1532<section title="409 Conflict" anchor="status.409">
1533  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1534  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1535<t>
1536   The request could not be completed due to a conflict with the current
1537   state of the resource. This code is only allowed in situations where
1538   it is expected that the user might be able to resolve the conflict
1539   and resubmit the request. The response body &SHOULD; include enough
1540   information for the user to recognize the source of the conflict.
1541   Ideally, the response entity would include enough information for the
1542   user or user agent to fix the problem; however, that might not be
1543   possible and is not required.
1544</t>
1545<t>
1546   Conflicts are most likely to occur in response to a PUT request. For
1547   example, if versioning were being used and the entity being PUT
1548   included changes to a resource which conflict with those made by an
1549   earlier (third-party) request, the server might use the 409 response
1550   to indicate that it can't complete the request. In this case, the
1551   response entity would likely contain a list of the differences
1552   between the two versions in a format defined by the response
1553   Content-Type.
1554</t>
1555</section>
1556
1557<section title="410 Gone" anchor="status.410">
1558  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1559  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1560<t>
1561   The requested resource is no longer available at the server and no
1562   forwarding address is known. This condition is expected to be
1563   considered permanent. Clients with link editing capabilities &SHOULD;
1564   delete references to the Request-URI after user approval. If the
1565   server does not know, or has no facility to determine, whether or not
1566   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1567   used instead. This response is cacheable unless indicated otherwise.
1568</t>
1569<t>
1570   The 410 response is primarily intended to assist the task of web
1571   maintenance by notifying the recipient that the resource is
1572   intentionally unavailable and that the server owners desire that
1573   remote links to that resource be removed. Such an event is common for
1574   limited-time, promotional services and for resources belonging to
1575   individuals no longer working at the server's site. It is not
1576   necessary to mark all permanently unavailable resources as "gone" or
1577   to keep the mark for any length of time -- that is left to the
1578   discretion of the server owner.
1579</t>
1580</section>
1581
1582<section title="411 Length Required" anchor="status.411">
1583  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1584  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1585<t>
1586   The server refuses to accept the request without a defined Content-Length.
1587   The client &MAY; repeat the request if it adds a valid
1588   Content-Length header field containing the length of the message-body
1589   in the request message.
1590</t>
1591</section>
1592
1593<section title="412 Precondition Failed" anchor="status.412">
1594  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1595  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1596<t>
1597   The precondition given in one or more of the request-header fields
1598   evaluated to false when it was tested on the server, as defined in
1599   &conditional;.
1600</t>
1601</section>
1602
1603<section title="413 Request Entity Too Large" anchor="status.413">
1604  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1605  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1606<t>
1607   The server is refusing to process a request because the request
1608   entity is larger than the server is willing or able to process. The
1609   server &MAY; close the connection to prevent the client from continuing
1610   the request.
1611</t>
1612<t>
1613   If the condition is temporary, the server &SHOULD; include a Retry-After
1614   header field to indicate that it is temporary and after what
1615   time the client &MAY; try again.
1616</t>
1617</section>
1618
1619<section title="414 Request-URI Too Long" anchor="status.414">
1620  <iref primary="true" item="414 Request-URI Too Long (status code)" x:for-anchor=""/>
1621  <iref primary="true" item="Status Codes" subitem="414 Request-URI Too Long" x:for-anchor=""/>
1622<t>
1623   The server is refusing to service the request because the Request-URI
1624   is longer than the server is willing to interpret. This rare
1625   condition is only likely to occur when a client has improperly
1626   converted a POST request to a GET request with long query
1627   information, when the client has descended into a URI "black hole" of
1628   redirection (e.g., a redirected URI prefix that points to a suffix of
1629   itself), or when the server is under attack by a client attempting to
1630   exploit security holes present in some servers using fixed-length
1631   buffers for reading or manipulating the Request-URI.
1632</t>
1633</section>
1634
1635<section title="415 Unsupported Media Type" anchor="status.415">
1636  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1637  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1638<t>
1639   The server is refusing to service the request because the entity of
1640   the request is in a format not supported by the requested resource
1641   for the requested method.
1642</t>
1643</section>
1644
1645<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1646  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1647  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1648<t>
1649   The request included a Range request-header field (&header-range;) and none of
1650   the range-specifier values in this field overlap the current extent
1651   of the selected resource.
1652</t>
1653</section>
1654
1655<section title="417 Expectation Failed" anchor="status.417">
1656  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
1657  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
1658<t>
1659   The expectation given in an Expect request-header field (see <xref target="header.expect"/>)
1660   could not be met by this server, or, if the server is a proxy,
1661   the server has unambiguous evidence that the request could not be met
1662   by the next-hop server.
1663</t>
1664</section>
1665</section>
1666
1667<section title="Server Error 5xx" anchor="status.5xx">
1668<t>
1669   Response status codes beginning with the digit "5" indicate cases in
1670   which the server is aware that it has erred or is incapable of
1671   performing the request. Except when responding to a HEAD request, the
1672   server &SHOULD; include an entity containing an explanation of the
1673   error situation, and whether it is a temporary or permanent
1674   condition. User agents &SHOULD; display any included entity to the
1675   user. These response codes are applicable to any request method.
1676</t>
1677
1678<section title="500 Internal Server Error" anchor="status.500">
1679  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
1680  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
1681<t>
1682   The server encountered an unexpected condition which prevented it
1683   from fulfilling the request.
1684</t>
1685</section>
1686
1687<section title="501 Not Implemented" anchor="status.501">
1688  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
1689  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
1690<t>
1691   The server does not support the functionality required to fulfill the
1692   request. This is the appropriate response when the server does not
1693   recognize the request method and is not capable of supporting it for
1694   any resource.
1695</t>
1696</section>
1697
1698<section title="502 Bad Gateway" anchor="status.502">
1699  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
1700  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
1701<t>
1702   The server, while acting as a gateway or proxy, received an invalid
1703   response from the upstream server it accessed in attempting to
1704   fulfill the request.
1705</t>
1706</section>
1707
1708<section title="503 Service Unavailable" anchor="status.503">
1709  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
1710  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
1711<t>
1712   The server is currently unable to handle the request due to a
1713   temporary overloading or maintenance of the server. The implication
1714   is that this is a temporary condition which will be alleviated after
1715   some delay. If known, the length of the delay &MAY; be indicated in a
1716   Retry-After header. If no Retry-After is given, the client &SHOULD;
1717   handle the response as it would for a 500 response.
1718  <list><t>
1719      <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
1720      server must use it when becoming overloaded. Some servers may wish
1721      to simply refuse the connection.
1722  </t></list>
1723</t>
1724</section>
1725
1726<section title="504 Gateway Timeout" anchor="status.504">
1727  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
1728  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
1729<t>
1730   The server, while acting as a gateway or proxy, did not receive a
1731   timely response from the upstream server specified by the URI (e.g.
1732   HTTP, FTP, LDAP) or some other auxiliary server (e.g. DNS) it needed
1733   to access in attempting to complete the request.
1734  <list><t>
1735      <x:h>Note:</x:h> Note to implementors: some deployed proxies are known to
1736      return 400 or 500 when DNS lookups time out.
1737  </t></list>
1738</t>
1739</section>
1740
1741<section title="505 HTTP Version Not Supported" anchor="status.505">
1742  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
1743  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
1744<t>
1745   The server does not support, or refuses to support, the protocol
1746   version that was used in the request message. The server is
1747   indicating that it is unable or unwilling to complete the request
1748   using the same major version as the client, as described in &http-version;,
1749   other than with this error message. The response &SHOULD; contain
1750   an entity describing why that version is not supported and what other
1751   protocols are supported by that server.
1752</t>
1753
1754</section>
1755</section>
1756</section>
1757
1758
1759<section title="Header Field Definitions" anchor="header.fields">
1760<t>
1761   This section defines the syntax and semantics of HTTP/1.1 header fields
1762   related to request and response semantics.
1763</t>
1764<t>
1765   For entity-header fields, both sender and recipient refer to either the
1766   client or the server, depending on who sends and who receives the entity.
1767</t>
1768
1769<section title="Allow" anchor="header.allow">
1770  <iref primary="true" item="Allow header" x:for-anchor=""/>
1771  <iref primary="true" item="Headers" subitem="Allow" x:for-anchor=""/>
1772  <x:anchor-alias value="Allow"/>
1773<t>
1774      The Allow response-header field lists the set of methods advertised as
1775      supported by the resource identified by the Request-URI. The purpose of
1776      this field is strictly to inform the recipient of valid methods
1777      associated with the resource. An Allow header field &MUST; be
1778      present in a 405 (Method Not Allowed) response.
1779</t>
1780<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/>
1781  <x:ref>Allow</x:ref>   = "Allow" ":" #<x:ref>Method</x:ref>
1782</artwork></figure>
1783<t>
1784      Example of use:
1785</t>
1786<figure><artwork type="example">
1787       Allow: GET, HEAD, PUT
1788</artwork></figure>
1789<t>
1790      The actual set of allowed methods is defined
1791      by the origin server at the time of each request.
1792</t>
1793<t>
1794      A proxy &MUST-NOT; modify the Allow header field even if it does not
1795      understand all the methods specified, since the user agent might
1796      have other means of communicating with the origin server.
1797</t>
1798</section>
1799
1800<section title="Expect" anchor="header.expect">
1801  <iref primary="true" item="Expect header" x:for-anchor=""/>
1802  <iref primary="true" item="Headers" subitem="Expect" x:for-anchor=""/>
1803  <x:anchor-alias value="Expect"/>
1804  <x:anchor-alias value="expectation"/>
1805  <x:anchor-alias value="expectation-extension"/>
1806  <x:anchor-alias value="expect-params"/>
1807<t>
1808   The Expect request-header field is used to indicate that particular
1809   server behaviors are required by the client.
1810</t>
1811<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Expect"/><iref primary="true" item="Grammar" subitem="expectation"/><iref primary="true" item="Grammar" subitem="expectation-extension"/><iref primary="true" item="Grammar" subitem="expect-params"/>
1812  <x:ref>Expect</x:ref>       =  "Expect" ":" 1#<x:ref>expectation</x:ref>
1813 
1814  <x:ref>expectation</x:ref>  =  "100-continue" | <x:ref>expectation-extension</x:ref>
1815  <x:ref>expectation-extension</x:ref> =  <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> | <x:ref>quoted-string</x:ref> )
1816                           *<x:ref>expect-params</x:ref> ]
1817  <x:ref>expect-params</x:ref> =  ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> | <x:ref>quoted-string</x:ref> ) ]
1818</artwork></figure>
1819<t>
1820   A server that does not understand or is unable to comply with any of
1821   the expectation values in the Expect field of a request &MUST; respond
1822   with appropriate error status. The server &MUST; respond with a 417
1823   (Expectation Failed) status if any of the expectations cannot be met
1824   or, if there are other problems with the request, some other 4xx
1825   status.
1826</t>
1827<t>
1828   This header field is defined with extensible syntax to allow for
1829   future extensions. If a server receives a request containing an
1830   Expect field that includes an expectation-extension that it does not
1831   support, it &MUST; respond with a 417 (Expectation Failed) status.
1832</t>
1833<t>
1834   Comparison of expectation values is case-insensitive for unquoted
1835   tokens (including the 100-continue token), and is case-sensitive for
1836   quoted-string expectation-extensions.
1837</t>
1838<t>
1839   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
1840   return a 417 (Expectation Failed) status if it receives a request
1841   with an expectation that it cannot meet. However, the Expect
1842   request-header itself is end-to-end; it &MUST; be forwarded if the
1843   request is forwarded.
1844</t>
1845<t>
1846   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
1847   Expect header.
1848</t>
1849<t>
1850   See &use100; for the use of the 100 (Continue) status.
1851</t>
1852</section>
1853
1854<section title="From" anchor="header.from">
1855  <iref primary="true" item="From header" x:for-anchor=""/>
1856  <iref primary="true" item="Headers" subitem="From" x:for-anchor=""/>
1857  <x:anchor-alias value="From"/>
1858  <x:anchor-alias value="mailbox"/>
1859<t>
1860   The From request-header field, if given, &SHOULD; contain an Internet
1861   e-mail address for the human user who controls the requesting user
1862   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
1863   in <xref x:sec="3.4" x:fmt="of" target="RFC2822"/>:
1864</t>
1865<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/>
1866  <x:ref>From</x:ref>    = "From" ":" <x:ref>mailbox</x:ref>
1867 
1868  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC2822"/>&gt;
1869</artwork></figure>
1870<t>
1871   An example is:
1872</t>
1873<figure><artwork type="example">
1874    From: webmaster@example.org
1875</artwork></figure>
1876<t>
1877   This header field &MAY; be used for logging purposes and as a means for
1878   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
1879   be used as an insecure form of access protection. The interpretation
1880   of this field is that the request is being performed on behalf of the
1881   person given, who accepts responsibility for the method performed. In
1882   particular, robot agents &SHOULD; include this header so that the
1883   person responsible for running the robot can be contacted if problems
1884   occur on the receiving end.
1885</t>
1886<t>
1887   The Internet e-mail address in this field &MAY; be separate from the
1888   Internet host which issued the request. For example, when a request
1889   is passed through a proxy the original issuer's address &SHOULD; be
1890   used.
1891</t>
1892<t>
1893   The client &SHOULD-NOT;  send the From header field without the user's
1894   approval, as it might conflict with the user's privacy interests or
1895   their site's security policy. It is strongly recommended that the
1896   user be able to disable, enable, and modify the value of this field
1897   at any time prior to a request.
1898</t>
1899</section>
1900
1901<section title="Location" anchor="header.location">
1902  <iref primary="true" item="Location header" x:for-anchor=""/>
1903  <iref primary="true" item="Headers" subitem="Location" x:for-anchor=""/>
1904  <x:anchor-alias value="Location"/>
1905<t>
1906   The Location response-header field is used for the identification of a
1907   new resource or to redirect the recipient to a location other than the
1908   Request-URI for completion of the request.  For 201 (Created)
1909   responses, the Location is that of the new resource which was created
1910   by the request. For 3xx responses, the location &SHOULD; indicate the
1911   server's preferred URI for automatic redirection to the resource. The
1912   field value consists of a single absolute URI.
1913</t>
1914<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/>
1915  <x:ref>Location</x:ref>       = "Location" ":" <x:ref>absoluteURI</x:ref> [ "#" <x:ref>fragment</x:ref> ]
1916</artwork></figure>
1917<t>
1918   An example is:
1919</t>
1920<figure><artwork type="example">
1921    Location: http://www.example.org/pub/WWW/People.html
1922</artwork></figure>
1923<t>
1924  <list><t>
1925      <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
1926      from Location in that the Content-Location identifies the original
1927      location of the entity enclosed in the request. It is therefore
1928      possible for a response to contain header fields for both Location
1929      and Content-Location.
1930  </t></list>
1931</t>
1932<t>
1933   There are circumstances in which a fragment identifier in a Location URL would not be appropriate:
1934   <list style="symbols">
1935      <t>With a 201 Created response, because in this usage the Location header specifies the URL for the entire created resource.</t>
1936      <t>With a 300 Multiple Choices, since the choice decision is intended to be made on resource characteristics and not fragment characteristics.</t>
1937      <t>With 305 Use Proxy.</t>
1938   </list>
1939</t>
1940</section>
1941
1942<section title="Max-Forwards" anchor="header.max-forwards">
1943  <iref primary="true" item="Max-Forwards header" x:for-anchor=""/>
1944  <iref primary="true" item="Headers" subitem="Max-Forwards" x:for-anchor=""/>
1945  <x:anchor-alias value="Max-Forwards"/>
1946<t>
1947   The Max-Forwards request-header field provides a mechanism with the
1948   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>) methods to limit the
1949   number of proxies or gateways that can forward the request to the
1950   next inbound server. This can be useful when the client is attempting
1951   to trace a request chain which appears to be failing or looping in
1952   mid-chain.
1953</t>
1954<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/>
1955  <x:ref>Max-Forwards</x:ref>   = "Max-Forwards" ":" 1*<x:ref>DIGIT</x:ref>
1956</artwork></figure>
1957<t>
1958   The Max-Forwards value is a decimal integer indicating the remaining
1959   number of times this request message may be forwarded.
1960</t>
1961<t>
1962   Each proxy or gateway recipient of a TRACE or OPTIONS request
1963   containing a Max-Forwards header field &MUST; check and update its
1964   value prior to forwarding the request. If the received value is zero
1965   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
1966   respond as the final recipient. If the received Max-Forwards value is
1967   greater than zero, then the forwarded message &MUST; contain an updated
1968   Max-Forwards field with a value decremented by one (1).
1969</t>
1970<t>
1971   The Max-Forwards header field &MAY; be ignored for all other methods
1972   defined by this specification and for any extension methods for which
1973   it is not explicitly referred to as part of that method definition.
1974</t>
1975</section>
1976
1977<section title="Referer" anchor="header.referer">
1978  <iref primary="true" item="Referer header" x:for-anchor=""/>
1979  <iref primary="true" item="Headers" subitem="Referer" x:for-anchor=""/>
1980  <x:anchor-alias value="Referer"/>
1981<t>
1982   The Referer[sic] request-header field allows the client to specify,
1983   for the server's benefit, the address (URI) of the resource from
1984   which the Request-URI was obtained (the "referrer", although the
1985   header field is misspelled.) The Referer request-header allows a
1986   server to generate lists of back-links to resources for interest,
1987   logging, optimized caching, etc. It also allows obsolete or mistyped
1988   links to be traced for maintenance. The Referer field &MUST-NOT; be
1989   sent if the Request-URI was obtained from a source that does not have
1990   its own URI, such as input from the user keyboard.
1991</t>
1992<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/>
1993  <x:ref>Referer</x:ref>        = "Referer" ":" ( <x:ref>absoluteURI</x:ref> | <x:ref>relativeURI</x:ref> )
1994</artwork></figure>
1995<t>
1996   Example:
1997</t>
1998<figure><artwork type="example">
1999    Referer: http://www.example.org/hypertext/Overview.html
2000</artwork></figure>
2001<t>
2002   If the field value is a relative URI, it &SHOULD; be interpreted
2003   relative to the Request-URI. The URI &MUST-NOT; include a fragment. See
2004   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2005</t>
2006</section>
2007
2008<section title="Retry-After" anchor="header.retry-after">
2009  <iref primary="true" item="Retry-After header" x:for-anchor=""/>
2010  <iref primary="true" item="Headers" subitem="Retry-After" x:for-anchor=""/>
2011  <x:anchor-alias value="Retry-After"/>
2012<t>
2013   The Retry-After response-header field can be used with a 503 (Service
2014   Unavailable) response to indicate how long the service is expected to
2015   be unavailable to the requesting client. This field &MAY; also be used
2016   with any 3xx (Redirection) response to indicate the minimum time the
2017   user-agent is asked wait before issuing the redirected request. The
2018   value of this field can be either an HTTP-date or an integer number
2019   of seconds (in decimal) after the time of the response.
2020</t>
2021<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/>
2022  <x:ref>Retry-After</x:ref>   = "Retry-After" ":" ( <x:ref>HTTP-date</x:ref> | <x:ref>delta-seconds</x:ref> )
2023</artwork></figure>
2024<t anchor="rule.delta-seconds">
2025  <x:anchor-alias value="delta-seconds"/>
2026   Time spans are non-negative decimal integers, representing time in
2027   seconds.
2028</t>
2029<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2030  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2031</artwork></figure>
2032<t>
2033   Two examples of its use are
2034</t>
2035<figure><artwork type="example">
2036    Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2037    Retry-After: 120
2038</artwork></figure>
2039<t>
2040   In the latter example, the delay is 2 minutes.
2041</t>
2042</section>
2043
2044<section title="Server" anchor="header.server">
2045  <iref primary="true" item="Server header" x:for-anchor=""/>
2046  <iref primary="true" item="Headers" subitem="Server" x:for-anchor=""/>
2047  <x:anchor-alias value="Server"/>
2048<t>
2049   The Server response-header field contains information about the
2050   software used by the origin server to handle the request. The field
2051   can contain multiple product tokens (&product-tokens;) and comments
2052   identifying the server and any significant subproducts. The product
2053   tokens are listed in order of their significance for identifying the
2054   application.
2055</t>
2056<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/>
2057  <x:ref>Server</x:ref>         = "Server" ":" 1*( <x:ref>product</x:ref> | <x:ref>comment</x:ref> )
2058</artwork></figure>
2059<t>
2060   Example:
2061</t>
2062<figure><artwork type="example">
2063    Server: CERN/3.0 libwww/2.17
2064</artwork></figure>
2065<t>
2066   If the response is being forwarded through a proxy, the proxy
2067   application &MUST-NOT; modify the Server response-header. Instead, it
2068   &MUST; include a Via field (as described in &header-via;).
2069  <list><t>
2070      <x:h>Note:</x:h> Revealing the specific software version of the server might
2071      allow the server machine to become more vulnerable to attacks
2072      against software that is known to contain security holes. Server
2073      implementors are encouraged to make this field a configurable
2074      option.
2075  </t></list>
2076</t>
2077</section>
2078
2079<section title="User-Agent" anchor="header.user-agent">
2080  <iref primary="true" item="User-Agent header" x:for-anchor=""/>
2081  <iref primary="true" item="Headers" subitem="User-Agent" x:for-anchor=""/>
2082  <x:anchor-alias value="User-Agent"/>
2083<t>
2084   The User-Agent request-header field contains information about the
2085   user agent originating the request. This is for statistical purposes,
2086   the tracing of protocol violations, and automated recognition of user
2087   agents for the sake of tailoring responses to avoid particular user
2088   agent limitations. User agents &SHOULD; include this field with
2089   requests. The field can contain multiple product tokens (&product-tokens;)
2090   and comments identifying the agent and any subproducts which form a
2091   significant part of the user agent. By convention, the product tokens
2092   are listed in order of their significance for identifying the
2093   application.
2094</t>
2095<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/>
2096  <x:ref>User-Agent</x:ref>     = "User-Agent" ":" 1*( <x:ref>product</x:ref> | <x:ref>comment</x:ref> )
2097</artwork></figure>
2098<t>
2099   Example:
2100</t>
2101<figure><artwork type="example">
2102    User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2103</artwork></figure>
2104</section>
2105
2106</section>
2107
2108<section title="IANA Considerations" anchor="IANA.considerations">
2109
2110<section title="Method Registry" anchor="method.registration">
2111<t>
2112  The registration procedure for HTTP Methods is defined by
2113  <xref target="method.registry"/> of this document.
2114</t>
2115<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2116<!--(START)-->
2117<t xmlns:x="http://purl.org/net/xml2rfc/ext">
2118    The HTTP Method Registry located at <eref target="http://www.iana.org/assignments/http-methods"/>
2119    should be populated with the registrations below:
2120  </t>
2121<texttable xmlns:x="http://purl.org/net/xml2rfc/ext" align="left">
2122   <ttcol>Method</ttcol>
2123   <ttcol>Reference</ttcol>
2124
2125   <c>CONNECT</c>
2126   <c>
2127      <xref target="CONNECT"/>
2128   </c>
2129
2130   <c>DELETE</c>
2131   <c>
2132      <xref target="DELETE"/>
2133   </c>
2134
2135   <c>GET</c>
2136   <c>
2137      <xref target="GET"/>
2138   </c>
2139
2140   <c>HEAD</c>
2141   <c>
2142      <xref target="HEAD"/>
2143   </c>
2144
2145   <c>OPTIONS</c>
2146   <c>
2147      <xref target="OPTIONS"/>
2148   </c>
2149
2150   <c>POST</c>
2151   <c>
2152      <xref target="POST"/>
2153   </c>
2154
2155   <c>PUT</c>
2156   <c>
2157      <xref target="PUT"/>
2158   </c>
2159
2160   <c>TRACE</c>
2161   <c>
2162      <xref target="TRACE"/>
2163   </c>
2164</texttable>
2165<!--(END)-->
2166</section>
2167
2168<section title="Status Code Registry" anchor="status.code.registration">
2169<t>
2170  The registration procedure for HTTP Status Codes -- previously defined
2171  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> -- is now defined
2172  by <xref target="status.code.registry"/> of this document.
2173</t>
2174<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2175<!--(START)-->
2176<t xmlns:x="http://purl.org/net/xml2rfc/ext">
2177    The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2178    should be updated with the registrations below:
2179  </t>
2180<texttable xmlns:x="http://purl.org/net/xml2rfc/ext">
2181   <ttcol>Value</ttcol>
2182   <ttcol>Description</ttcol>
2183   <ttcol>Reference</ttcol>
2184
2185   <c>100</c>
2186   <c>Continue</c>
2187   <c>
2188      <xref target="status.100"/>
2189   </c>
2190
2191   <c>101</c>
2192   <c>Switching Protocols</c>
2193   <c>
2194      <xref target="status.101"/>
2195   </c>
2196
2197   <c>200</c>
2198   <c>OK</c>
2199   <c>
2200      <xref target="status.200"/>
2201   </c>
2202
2203   <c>201</c>
2204   <c>Created</c>
2205   <c>
2206      <xref target="status.201"/>
2207   </c>
2208
2209   <c>202</c>
2210   <c>Accepted</c>
2211   <c>
2212      <xref target="status.202"/>
2213   </c>
2214
2215   <c>203</c>
2216   <c>Non-Authoritative Information</c>
2217   <c>
2218      <xref target="status.203"/>
2219   </c>
2220
2221   <c>204</c>
2222   <c>No Content</c>
2223   <c>
2224      <xref target="status.204"/>
2225   </c>
2226
2227   <c>205</c>
2228   <c>Reset Content</c>
2229   <c>
2230      <xref target="status.205"/>
2231   </c>
2232
2233   <c>206</c>
2234   <c>Partial Content</c>
2235   <c>
2236      <xref target="status.206"/>
2237   </c>
2238
2239   <c>300</c>
2240   <c>Multiple Choices</c>
2241   <c>
2242      <xref target="status.300"/>
2243   </c>
2244
2245   <c>301</c>
2246   <c>Moved Permanently</c>
2247   <c>
2248      <xref target="status.301"/>
2249   </c>
2250
2251   <c>302</c>
2252   <c>Found</c>
2253   <c>
2254      <xref target="status.302"/>
2255   </c>
2256
2257   <c>303</c>
2258   <c>See Other</c>
2259   <c>
2260      <xref target="status.303"/>
2261   </c>
2262
2263   <c>304</c>
2264   <c>Not Modified</c>
2265   <c>
2266      <xref target="status.304"/>
2267   </c>
2268
2269   <c>305</c>
2270   <c>Use Proxy</c>
2271   <c>
2272      <xref target="status.305"/>
2273   </c>
2274
2275   <c>306</c>
2276   <c>(Unused)</c>
2277   <c>
2278      <xref target="status.306"/>
2279   </c>
2280
2281   <c>307</c>
2282   <c>Temporary Redirect</c>
2283   <c>
2284      <xref target="status.307"/>
2285   </c>
2286
2287   <c>400</c>
2288   <c>Bad Request</c>
2289   <c>
2290      <xref target="status.400"/>
2291   </c>
2292
2293   <c>401</c>
2294   <c>Unauthorized</c>
2295   <c>
2296      <xref target="status.401"/>
2297   </c>
2298
2299   <c>402</c>
2300   <c>Payment Required</c>
2301   <c>
2302      <xref target="status.402"/>
2303   </c>
2304
2305   <c>403</c>
2306   <c>Forbidden</c>
2307   <c>
2308      <xref target="status.403"/>
2309   </c>
2310
2311   <c>404</c>
2312   <c>Not Found</c>
2313   <c>
2314      <xref target="status.404"/>
2315   </c>
2316
2317   <c>405</c>
2318   <c>Method Not Allowed</c>
2319   <c>
2320      <xref target="status.405"/>
2321   </c>
2322
2323   <c>406</c>
2324   <c>Not Acceptable</c>
2325   <c>
2326      <xref target="status.406"/>
2327   </c>
2328
2329   <c>407</c>
2330   <c>Proxy Authentication Required</c>
2331   <c>
2332      <xref target="status.407"/>
2333   </c>
2334
2335   <c>408</c>
2336   <c>Request Timeout</c>
2337   <c>
2338      <xref target="status.408"/>
2339   </c>
2340
2341   <c>409</c>
2342   <c>Conflict</c>
2343   <c>
2344      <xref target="status.409"/>
2345   </c>
2346
2347   <c>410</c>
2348   <c>Gone</c>
2349   <c>
2350      <xref target="status.410"/>
2351   </c>
2352
2353   <c>411</c>
2354   <c>Length Required</c>
2355   <c>
2356      <xref target="status.411"/>
2357   </c>
2358
2359   <c>412</c>
2360   <c>Precondition Failed</c>
2361   <c>
2362      <xref target="status.412"/>
2363   </c>
2364
2365   <c>413</c>
2366   <c>Request Entity Too Large</c>
2367   <c>
2368      <xref target="status.413"/>
2369   </c>
2370
2371   <c>414</c>
2372   <c>Request-URI Too Long</c>
2373   <c>
2374      <xref target="status.414"/>
2375   </c>
2376
2377   <c>415</c>
2378   <c>Unsupported Media Type</c>
2379   <c>
2380      <xref target="status.415"/>
2381   </c>
2382
2383   <c>416</c>
2384   <c>Requested Range Not Satisfiable</c>
2385   <c>
2386      <xref target="status.416"/>
2387   </c>
2388
2389   <c>417</c>
2390   <c>Expectation Failed</c>
2391   <c>
2392      <xref target="status.417"/>
2393   </c>
2394
2395   <c>500</c>
2396   <c>Internal Server Error</c>
2397   <c>
2398      <xref target="status.500"/>
2399   </c>
2400
2401   <c>501</c>
2402   <c>Not Implemented</c>
2403   <c>
2404      <xref target="status.501"/>
2405   </c>
2406
2407   <c>502</c>
2408   <c>Bad Gateway</c>
2409   <c>
2410      <xref target="status.502"/>
2411   </c>
2412
2413   <c>503</c>
2414   <c>Service Unavailable</c>
2415   <c>
2416      <xref target="status.503"/>
2417   </c>
2418
2419   <c>504</c>
2420   <c>Gateway Timeout</c>
2421   <c>
2422      <xref target="status.504"/>
2423   </c>
2424
2425   <c>505</c>
2426   <c>HTTP Version Not Supported</c>
2427   <c>
2428      <xref target="status.505"/>
2429   </c>
2430</texttable>
2431<!--(END)-->
2432</section>
2433<section title="Message Header Registration" anchor="message.header.registration">
2434<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2435<!--(START)-->
2436<t>
2437    The Message Header Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> should be updated
2438    with the permanent registrations below (see <xref target="RFC3864"/>):
2439  </t>
2440<texttable>
2441   <ttcol>Header Field Name</ttcol>
2442   <ttcol>Protocol</ttcol>
2443   <ttcol>Status</ttcol>
2444   <ttcol>Reference</ttcol>
2445
2446   <c>Allow</c>
2447   <c>http</c>
2448   <c>standard</c>
2449   <c>
2450      <xref target="header.allow"/>
2451   </c>
2452
2453   <c>Expect</c>
2454   <c>http</c>
2455   <c>standard</c>
2456   <c>
2457      <xref target="header.expect"/>
2458   </c>
2459
2460   <c>From</c>
2461   <c>http</c>
2462   <c>standard</c>
2463   <c>
2464      <xref target="header.from"/>
2465   </c>
2466
2467   <c>Location</c>
2468   <c>http</c>
2469   <c>standard</c>
2470   <c>
2471      <xref target="header.location"/>
2472   </c>
2473
2474   <c>Max-Forwards</c>
2475   <c>http</c>
2476   <c>standard</c>
2477   <c>
2478      <xref target="header.max-forwards"/>
2479   </c>
2480
2481   <c>Referer</c>
2482   <c>http</c>
2483   <c>standard</c>
2484   <c>
2485      <xref target="header.referer"/>
2486   </c>
2487
2488   <c>Retry-After</c>
2489   <c>http</c>
2490   <c>standard</c>
2491   <c>
2492      <xref target="header.retry-after"/>
2493   </c>
2494
2495   <c>Server</c>
2496   <c>http</c>
2497   <c>standard</c>
2498   <c>
2499      <xref target="header.server"/>
2500   </c>
2501
2502   <c>User-Agent</c>
2503   <c>http</c>
2504   <c>standard</c>
2505   <c>
2506      <xref target="header.user-agent"/>
2507   </c>
2508</texttable>
2509<t>
2510    The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2511</t>
2512<!--(END)-->
2513</section>
2514</section>
2515
2516<section title="Security Considerations" anchor="security.considerations">
2517<t>
2518   This section is meant to inform application developers, information
2519   providers, and users of the security limitations in HTTP/1.1 as
2520   described by this document. The discussion does not include
2521   definitive solutions to the problems revealed, though it does make
2522   some suggestions for reducing security risks.
2523</t>
2524
2525<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2526<t>
2527   Like any generic data transfer protocol, HTTP cannot regulate the
2528   content of the data that is transferred, nor is there any a priori
2529   method of determining the sensitivity of any particular piece of
2530   information within the context of any given request. Therefore,
2531   applications &SHOULD; supply as much control over this information as
2532   possible to the provider of that information. Four header fields are
2533   worth special mention in this context: Server, Via, Referer and From.
2534</t>
2535<t>
2536   Revealing the specific software version of the server might allow the
2537   server machine to become more vulnerable to attacks against software
2538   that is known to contain security holes. Implementors &SHOULD; make the
2539   Server header field a configurable option.
2540</t>
2541<t>
2542   Proxies which serve as a portal through a network firewall &SHOULD;
2543   take special precautions regarding the transfer of header information
2544   that identifies the hosts behind the firewall. In particular, they
2545   &SHOULD; remove, or replace with sanitized versions, any Via fields
2546   generated behind the firewall.
2547</t>
2548<t>
2549   The Referer header allows reading patterns to be studied and reverse
2550   links drawn. Although it can be very useful, its power can be abused
2551   if user details are not separated from the information contained in
2552   the Referer. Even when the personal information has been removed, the
2553   Referer header might indicate a private document's URI whose
2554   publication would be inappropriate.
2555</t>
2556<t>
2557   The information sent in the From field might conflict with the user's
2558   privacy interests or their site's security policy, and hence it
2559   &SHOULD-NOT;  be transmitted without the user being able to disable,
2560   enable, and modify the contents of the field. The user &MUST; be able
2561   to set the contents of this field within a user preference or
2562   application defaults configuration.
2563</t>
2564<t>
2565   We suggest, though do not require, that a convenient toggle interface
2566   be provided for the user to enable or disable the sending of From and
2567   Referer information.
2568</t>
2569<t>
2570   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref target="header.server"/>) header
2571   fields can sometimes be used to determine that a specific client or
2572   server have a particular security hole which might be exploited.
2573   Unfortunately, this same information is often used for other valuable
2574   purposes for which HTTP currently has no better mechanism.
2575</t>
2576</section>
2577
2578<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2579<t>
2580   Because the source of a link might be private information or might
2581   reveal an otherwise private information source, it is strongly
2582   recommended that the user be able to select whether or not the
2583   Referer field is sent. For example, a browser client could have a
2584   toggle switch for browsing openly/anonymously, which would
2585   respectively enable/disable the sending of Referer and From
2586   information.
2587</t>
2588<t>
2589   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2590   HTTP request if the referring page was transferred with a secure
2591   protocol.
2592</t>
2593<t>
2594   Authors of services should not use
2595   GET-based forms for the submission of sensitive data because that
2596   data will be encoded in the Request-URI. Many existing
2597   servers, proxies, and user agents log or display the Request-URI in
2598   places where it might be visible to third parties. Such services can
2599   use POST-based form submission instead.
2600</t>
2601</section>
2602
2603<section title="Location Headers and Spoofing" anchor="location.spoofing">
2604<t>
2605   If a single server supports multiple organizations that do not trust
2606   one another, then it &MUST; check the values of Location and Content-Location
2607   headers in responses that are generated under control of
2608   said organizations to make sure that they do not attempt to
2609   invalidate resources over which they have no authority.
2610</t>
2611</section>
2612
2613</section>
2614
2615<section title="Acknowledgments" anchor="ack">
2616</section>
2617</middle>
2618<back>
2619
2620<references title="Normative References">
2621
2622<reference anchor="Part1">
2623  <front>
2624    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2625    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2626      <organization abbrev="Day Software">Day Software</organization>
2627      <address><email>fielding@gbiv.com</email></address>
2628    </author>
2629    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2630      <organization>One Laptop per Child</organization>
2631      <address><email>jg@laptop.org</email></address>
2632    </author>
2633    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2634      <organization abbrev="HP">Hewlett-Packard Company</organization>
2635      <address><email>JeffMogul@acm.org</email></address>
2636    </author>
2637    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2638      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2639      <address><email>henrikn@microsoft.com</email></address>
2640    </author>
2641    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2642      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2643      <address><email>LMM@acm.org</email></address>
2644    </author>
2645    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2646      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2647      <address><email>paulle@microsoft.com</email></address>
2648    </author>
2649    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2650      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2651      <address><email>timbl@w3.org</email></address>
2652    </author>
2653    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2654      <organization abbrev="W3C">World Wide Web Consortium</organization>
2655      <address><email>ylafon@w3.org</email></address>
2656    </author>
2657    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2658      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2659      <address><email>julian.reschke@greenbytes.de</email></address>
2660    </author>
2661    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2662  </front>
2663  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
2664  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
2665</reference>
2666
2667<reference anchor="Part3">
2668  <front>
2669    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
2670    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2671      <organization abbrev="Day Software">Day Software</organization>
2672      <address><email>fielding@gbiv.com</email></address>
2673    </author>
2674    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2675      <organization>One Laptop per Child</organization>
2676      <address><email>jg@laptop.org</email></address>
2677    </author>
2678    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2679      <organization abbrev="HP">Hewlett-Packard Company</organization>
2680      <address><email>JeffMogul@acm.org</email></address>
2681    </author>
2682    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2683      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2684      <address><email>henrikn@microsoft.com</email></address>
2685    </author>
2686    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2687      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2688      <address><email>LMM@acm.org</email></address>
2689    </author>
2690    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2691      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2692      <address><email>paulle@microsoft.com</email></address>
2693    </author>
2694    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2695      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2696      <address><email>timbl@w3.org</email></address>
2697    </author>
2698    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2699      <organization abbrev="W3C">World Wide Web Consortium</organization>
2700      <address><email>ylafon@w3.org</email></address>
2701    </author>
2702    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2703      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2704      <address><email>julian.reschke@greenbytes.de</email></address>
2705    </author>
2706    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2707  </front>
2708  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
2709  <x:source href="p3-payload.xml" basename="p3-payload"/>
2710</reference>
2711
2712<reference anchor="Part4">
2713  <front>
2714    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
2715    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2716      <organization abbrev="Day Software">Day Software</organization>
2717      <address><email>fielding@gbiv.com</email></address>
2718    </author>
2719    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2720      <organization>One Laptop per Child</organization>
2721      <address><email>jg@laptop.org</email></address>
2722    </author>
2723    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2724      <organization abbrev="HP">Hewlett-Packard Company</organization>
2725      <address><email>JeffMogul@acm.org</email></address>
2726    </author>
2727    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2728      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2729      <address><email>henrikn@microsoft.com</email></address>
2730    </author>
2731    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2732      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2733      <address><email>LMM@acm.org</email></address>
2734    </author>
2735    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2736      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2737      <address><email>paulle@microsoft.com</email></address>
2738    </author>
2739    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2740      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2741      <address><email>timbl@w3.org</email></address>
2742    </author>
2743    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2744      <organization abbrev="W3C">World Wide Web Consortium</organization>
2745      <address><email>ylafon@w3.org</email></address>
2746    </author>
2747    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2748      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2749      <address><email>julian.reschke@greenbytes.de</email></address>
2750    </author>
2751    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2752  </front>
2753  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
2754  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
2755</reference>
2756
2757<reference anchor="Part5">
2758  <front>
2759    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
2760    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2761      <organization abbrev="Day Software">Day Software</organization>
2762      <address><email>fielding@gbiv.com</email></address>
2763    </author>
2764    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2765      <organization>One Laptop per Child</organization>
2766      <address><email>jg@laptop.org</email></address>
2767    </author>
2768    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2769      <organization abbrev="HP">Hewlett-Packard Company</organization>
2770      <address><email>JeffMogul@acm.org</email></address>
2771    </author>
2772    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2773      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2774      <address><email>henrikn@microsoft.com</email></address>
2775    </author>
2776    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2777      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2778      <address><email>LMM@acm.org</email></address>
2779    </author>
2780    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2781      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2782      <address><email>paulle@microsoft.com</email></address>
2783    </author>
2784    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2785      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2786      <address><email>timbl@w3.org</email></address>
2787    </author>
2788    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2789      <organization abbrev="W3C">World Wide Web Consortium</organization>
2790      <address><email>ylafon@w3.org</email></address>
2791    </author>
2792    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2793      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2794      <address><email>julian.reschke@greenbytes.de</email></address>
2795    </author>
2796    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2797  </front>
2798  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
2799  <x:source href="p5-range.xml" basename="p5-range"/>
2800</reference>
2801
2802<reference anchor="Part6">
2803  <front>
2804    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
2805    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2806      <organization abbrev="Day Software">Day Software</organization>
2807      <address><email>fielding@gbiv.com</email></address>
2808    </author>
2809    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2810      <organization>One Laptop per Child</organization>
2811      <address><email>jg@laptop.org</email></address>
2812    </author>
2813    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2814      <organization abbrev="HP">Hewlett-Packard Company</organization>
2815      <address><email>JeffMogul@acm.org</email></address>
2816    </author>
2817    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2818      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2819      <address><email>henrikn@microsoft.com</email></address>
2820    </author>
2821    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2822      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2823      <address><email>LMM@acm.org</email></address>
2824    </author>
2825    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2826      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2827      <address><email>paulle@microsoft.com</email></address>
2828    </author>
2829    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2830      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2831      <address><email>timbl@w3.org</email></address>
2832    </author>
2833    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2834      <organization abbrev="W3C">World Wide Web Consortium</organization>
2835      <address><email>ylafon@w3.org</email></address>
2836    </author>
2837    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2838      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2839      <address><email>julian.reschke@greenbytes.de</email></address>
2840    </author>
2841    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2842  </front>
2843  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
2844  <x:source href="p6-cache.xml" basename="p6-cache"/>
2845</reference>
2846
2847<reference anchor="Part7">
2848  <front>
2849    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
2850    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2851      <organization abbrev="Day Software">Day Software</organization>
2852      <address><email>fielding@gbiv.com</email></address>
2853    </author>
2854    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2855      <organization>One Laptop per Child</organization>
2856      <address><email>jg@laptop.org</email></address>
2857    </author>
2858    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2859      <organization abbrev="HP">Hewlett-Packard Company</organization>
2860      <address><email>JeffMogul@acm.org</email></address>
2861    </author>
2862    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2863      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2864      <address><email>henrikn@microsoft.com</email></address>
2865    </author>
2866    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2867      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2868      <address><email>LMM@acm.org</email></address>
2869    </author>
2870    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2871      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2872      <address><email>paulle@microsoft.com</email></address>
2873    </author>
2874    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2875      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2876      <address><email>timbl@w3.org</email></address>
2877    </author>
2878    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2879      <organization abbrev="W3C">World Wide Web Consortium</organization>
2880      <address><email>ylafon@w3.org</email></address>
2881    </author>
2882    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2883      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2884      <address><email>julian.reschke@greenbytes.de</email></address>
2885    </author>
2886    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2887  </front>
2888  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
2889  <x:source href="p7-auth.xml" basename="p7-auth"/>
2890</reference>
2891
2892<reference anchor="RFC2119">
2893  <front>
2894    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
2895    <author initials="S." surname="Bradner" fullname="Scott Bradner">
2896      <organization>Harvard University</organization>
2897      <address><email>sob@harvard.edu</email></address>
2898    </author>
2899    <date month="March" year="1997"/>
2900  </front>
2901  <seriesInfo name="BCP" value="14"/>
2902  <seriesInfo name="RFC" value="2119"/>
2903</reference>
2904
2905</references>
2906
2907<references title="Informative References">
2908
2909<reference anchor="RFC1945">
2910  <front>
2911    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
2912    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2913      <organization>MIT, Laboratory for Computer Science</organization>
2914      <address><email>timbl@w3.org</email></address>
2915    </author>
2916    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
2917      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
2918      <address><email>fielding@ics.uci.edu</email></address>
2919    </author>
2920    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
2921      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
2922      <address><email>frystyk@w3.org</email></address>
2923    </author>
2924    <date month="May" year="1996"/>
2925  </front>
2926  <seriesInfo name="RFC" value="1945"/>
2927</reference>
2928
2929<reference anchor="RFC2068">
2930  <front>
2931    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
2932    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
2933      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
2934      <address><email>fielding@ics.uci.edu</email></address>
2935    </author>
2936    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2937      <organization>MIT Laboratory for Computer Science</organization>
2938      <address><email>jg@w3.org</email></address>
2939    </author>
2940    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2941      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
2942      <address><email>mogul@wrl.dec.com</email></address>
2943    </author>
2944    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
2945      <organization>MIT Laboratory for Computer Science</organization>
2946      <address><email>frystyk@w3.org</email></address>
2947    </author>
2948    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2949      <organization>MIT Laboratory for Computer Science</organization>
2950      <address><email>timbl@w3.org</email></address>
2951    </author>
2952    <date month="January" year="1997"/>
2953  </front>
2954  <seriesInfo name="RFC" value="2068"/>
2955</reference>
2956
2957<reference anchor="RFC2616">
2958  <front>
2959    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
2960    <author initials="R." surname="Fielding" fullname="R. Fielding">
2961      <organization>University of California, Irvine</organization>
2962      <address><email>fielding@ics.uci.edu</email></address>
2963    </author>
2964    <author initials="J." surname="Gettys" fullname="J. Gettys">
2965      <organization>W3C</organization>
2966      <address><email>jg@w3.org</email></address>
2967    </author>
2968    <author initials="J." surname="Mogul" fullname="J. Mogul">
2969      <organization>Compaq Computer Corporation</organization>
2970      <address><email>mogul@wrl.dec.com</email></address>
2971    </author>
2972    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
2973      <organization>MIT Laboratory for Computer Science</organization>
2974      <address><email>frystyk@w3.org</email></address>
2975    </author>
2976    <author initials="L." surname="Masinter" fullname="L. Masinter">
2977      <organization>Xerox Corporation</organization>
2978      <address><email>masinter@parc.xerox.com</email></address>
2979    </author>
2980    <author initials="P." surname="Leach" fullname="P. Leach">
2981      <organization>Microsoft Corporation</organization>
2982      <address><email>paulle@microsoft.com</email></address>
2983    </author>
2984    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
2985      <organization>W3C</organization>
2986      <address><email>timbl@w3.org</email></address>
2987    </author>
2988    <date month="June" year="1999"/>
2989  </front>
2990  <seriesInfo name="RFC" value="2616"/>
2991</reference>
2992
2993<reference anchor='RFC2817'>
2994  <front>
2995    <title>Upgrading to TLS Within HTTP/1.1</title>
2996    <author initials='R.' surname='Khare' fullname='R. Khare'>
2997      <organization>4K Associates / UC Irvine</organization>
2998      <address><email>rohit@4K-associates.com</email></address>
2999    </author>
3000    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3001      <organization>Agranat Systems, Inc.</organization>
3002      <address><email>lawrence@agranat.com</email></address>
3003    </author>
3004    <date year='2000' month='May' />
3005  </front>
3006  <seriesInfo name='RFC' value='2817' />
3007</reference>
3008
3009<reference anchor="RFC2822">
3010  <front>
3011    <title>Internet Message Format</title>
3012    <author initials="P." surname="Resnick" fullname="P. Resnick">
3013      <organization>QUALCOMM Incorporated</organization>
3014    </author>
3015    <date year="2001" month="April"/>
3016  </front> 
3017  <seriesInfo name="RFC" value="2822"/>
3018</reference>
3019
3020<reference anchor='RFC3864'>
3021  <front>
3022    <title>Registration Procedures for Message Header Fields</title>
3023    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3024      <organization>Nine by Nine</organization>
3025      <address><email>GK-IETF@ninebynine.org</email></address>
3026    </author>
3027    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3028      <organization>BEA Systems</organization>
3029      <address><email>mnot@pobox.com</email></address>
3030    </author>
3031    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3032      <organization>HP Labs</organization>
3033      <address><email>JeffMogul@acm.org</email></address>
3034    </author>
3035    <date year='2004' month='September' />
3036  </front>
3037  <seriesInfo name='BCP' value='90' />
3038  <seriesInfo name='RFC' value='3864' />
3039</reference>
3040
3041<reference anchor='RFC5226'>
3042  <front>
3043    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3044    <author initials='T.' surname='Narten' fullname='T. Narten'>
3045      <organization>IBM</organization>
3046      <address><email>narten@us.ibm.com</email></address>
3047    </author>
3048    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3049      <organization>Google</organization>
3050      <address><email>Harald@Alvestrand.no</email></address>
3051    </author>
3052    <date year='2008' month='May' />
3053  </front>
3054  <seriesInfo name='BCP' value='26' />
3055  <seriesInfo name='RFC' value='5226' />
3056</reference>
3057
3058</references>
3059
3060<section title="Compatibility with Previous Versions" anchor="compatibility">
3061<section title="Changes from RFC 2068" anchor="changes.from.rfc.2068">
3062<t>
3063   Clarified which error code should be used for inbound server failures
3064   (e.g. DNS failures). (<xref target="status.504"/>).
3065</t>
3066<t>
3067   201 (Created) had a race that required an Etag be sent when a resource is
3068   first created. (<xref target="status.201"/>).
3069</t>
3070<t>
3071   Rewrite of message transmission requirements to make it much harder
3072   for implementors to get it wrong, as the consequences of errors here
3073   can have significant impact on the Internet, and to deal with the
3074   following problems:
3075  <list style="numbers">
3076      <t>Changing "HTTP/1.1 or later" to "HTTP/1.1", in contexts where
3077         this was incorrectly placing a requirement on the behavior of
3078         an implementation of a future version of HTTP/1.x</t>
3079
3080      <t>Made it clear that user-agents should retry requests, not
3081         "clients" in general.</t>
3082
3083      <t>Converted requirements for clients to ignore unexpected 100
3084         (Continue) responses, and for proxies to forward 100 responses,
3085         into a general requirement for 1xx responses.</t>
3086
3087      <t>Modified some TCP-specific language, to make it clearer that
3088         non-TCP transports are possible for HTTP.</t>
3089
3090      <t>Require that the origin server &MUST-NOT; wait for the request
3091         body before it sends a required 100 (Continue) response.</t>
3092
3093      <t>Allow, rather than require, a server to omit 100 (Continue) if
3094         it has already seen some of the request body.</t>
3095
3096      <t>Allow servers to defend against denial-of-service attacks and
3097         broken clients.</t>
3098  </list>
3099</t>
3100<t>
3101   This change adds the Expect header and 417 status code.
3102</t>
3103<t>
3104   Clean up confusion between 403 and 404 responses. (Section <xref target="status.403" format="counter"/>,
3105   <xref target="status.404" format="counter"/>, and <xref target="status.410" format="counter"/>)
3106</t>
3107<t>
3108   The PATCH<iref item="PATCH method" primary="true"/><iref item="Methods" subitem="PATCH" primary="true"/>, LINK<iref item="LINK method" primary="true"/><iref item="Methods" subitem="LINK" primary="true"/>, UNLINK<iref item="UNLINK method" primary="true"/><iref item="Methods" subitem="UNLINK" primary="true"/> methods were defined but not commonly
3109   implemented in previous versions of this specification. See <xref target="RFC2068" x:fmt="of" x:sec="19.6.1"/>.
3110</t>
3111</section>
3112
3113<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3114<t>
3115  This document takes over the Status Code Registry, previously defined
3116  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3117  (<xref target="status.code.registry"/>)
3118</t>
3119<t>
3120  Clarify definition of POST.
3121  (<xref target="POST"/>)
3122</t>
3123<t>
3124  Failed to consider that there are
3125  many other request methods that are safe to automatically redirect,
3126  and further that the user agent is able to make that determination
3127  based on the request method semantics.
3128  (Sections <xref format="counter" target="status.301"/>,
3129  <xref format="counter" target="status.302"/> and
3130  <xref format="counter" target="status.307"/>)
3131</t>
3132<t>
3133  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3134  It used to indicate that the requested resource must be accessed through the
3135  proxy given by the Location field. The Location field gave the URI of the
3136  proxy. The recipient was expected to repeat this single request via the proxy.
3137  (<xref target="status.305"/>)
3138</t>
3139<t>
3140  Reclassify Allow header as response header, removing the option to
3141  specify it in a PUT request.
3142  Relax the server requirement on the contents of the Allow header and
3143  remove requirement on clients to always trust the header value.
3144  (<xref target="header.allow"/>)
3145</t>
3146<t>
3147  Correct syntax of Location header to allow fragment,
3148  as referred symbol wasn't what was expected, and add some
3149  clarifications as to when it would not be appropriate.
3150  (<xref target="header.location"/>)
3151</t>
3152<t>
3153  In the description of the Server header, the Via field
3154  was described as a SHOULD. The requirement was and is stated
3155  correctly in the description of the Via header in &header-via;.
3156  (<xref target="header.server"/>)
3157</t>
3158</section>
3159
3160</section>
3161
3162<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3163
3164<section title="Since RFC2616">
3165<t>
3166  Extracted relevant partitions from <xref target="RFC2616"/>.
3167</t>
3168</section>
3169
3170<section title="Since draft-ietf-httpbis-p2-semantics-00">
3171<t>
3172  Closed issues:
3173  <list style="symbols"> 
3174    <t>
3175      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3176      "Via is a MUST"
3177      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3178    </t>
3179    <t>
3180      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3181      "Fragments allowed in Location"
3182      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3183    </t>
3184    <t>
3185      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3186      "Safe Methods vs Redirection"
3187      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3188    </t>
3189    <t>
3190      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3191      "Revise description of the POST method"
3192      (<eref target="http://purl.org/NET/http-errata#post"/>)
3193    </t>
3194    <t>
3195      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3196      "Normative and Informative references"
3197    </t>
3198    <t>
3199      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3200      "RFC2606 Compliance"
3201    </t>
3202    <t>
3203      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3204      "Informative references"
3205    </t>
3206    <t>
3207      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3208      "Redundant cross-references"
3209    </t>
3210  </list>
3211</t>
3212<t>
3213  Other changes:
3214  <list style="symbols"> 
3215    <t>
3216      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3217    </t>
3218  </list>
3219</t>
3220</section>
3221
3222<section title="Since draft-ietf-httpbis-p2-semantics-01">
3223<t>
3224  Closed issues:
3225  <list style="symbols"> 
3226    <t>
3227      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3228      "PUT side effects"
3229    </t>
3230    <t>
3231      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3232      "Duplicate Host header requirements"
3233    </t>
3234  </list>
3235</t>
3236<t>
3237  Ongoing work on ABNF conversion (<eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3238  <list style="symbols"> 
3239    <t>
3240      Move "Product Tokens" section (back) into Part 1, as "token" is used
3241      in the definition of the Upgrade header.
3242    </t>
3243    <t>
3244      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3245    </t>
3246    <t>
3247      Copy definition of delta-seconds from Part6 instead of referencing it.
3248    </t>
3249  </list>
3250</t>
3251</section>
3252
3253<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3254<t>
3255  Closed issues:
3256  <list style="symbols"> 
3257    <t>
3258      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3259      "Requiring Allow in 405 responses"
3260    </t>
3261    <t>
3262      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3263      "Status Code Registry"
3264    </t>
3265    <t>
3266      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3267      "Redirection vs. Location"
3268    </t>
3269    <t>
3270      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3271      "Cacheability of 303 response"
3272    </t>
3273    <t>
3274      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3275      "305 Use Proxy"
3276    </t>
3277    <t>
3278      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3279      "Classification for Allow header"
3280    </t>
3281    <t>
3282      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3283      "PUT - 'store under' vs 'store at'"
3284    </t>
3285  </list>
3286</t>
3287<t>
3288  Ongoing work on IANA Message Header Registration (<eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3289  <list style="symbols"> 
3290    <t>
3291      Reference RFC 3984, and update header registrations for headers defined
3292      in this document.
3293    </t>
3294  </list>
3295</t>
3296<t>
3297  Ongoing work on ABNF conversion (<eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3298  <list style="symbols"> 
3299    <t>
3300      Replace string literals when the string really is case-sensitive (method).
3301    </t>
3302  </list>
3303</t>
3304</section>
3305
3306<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3307<t>
3308  Closed issues:
3309  <list style="symbols"> 
3310    <t>
3311      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3312      "OPTIONS request bodies"
3313    </t>
3314    <t>
3315      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3316      "Description of CONNECT should refer to RFC2817"
3317    </t>
3318  </list>
3319</t>
3320<t>
3321  Ongoing work on Method Registry (<eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3322  <list style="symbols"> 
3323    <t>
3324      Added initial proposal for registration process, plus initial
3325      content (non-HTTP/1.1 methods to be added by a separate specification).
3326    </t>
3327  </list>
3328</t>
3329</section>
3330
3331</section>
3332
3333</back>
3334</rfc>
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