source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1167

Last change on this file since 1167 was 1167, checked in by julian.reschke@…, 9 years ago

remove unused ABNF imports (see #276)

  • Property svn:eol-style set to native
File size: 168.7 KB
Line 
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 "March">
16  <!ENTITY ID-YEAR "2011">
17  <!ENTITY mdash "&#8212;">
18  <!ENTITY notation                   "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY payload                    "<xref target='Part3' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY conditional                "<xref target='Part4' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY range                      "<xref target='Part5' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY caching                    "<xref target='Part6' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY auth                       "<xref target='Part7' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY combining-responses        "<xref target='Part6' x:rel='#combining.responses' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY content-negotiation        "<xref target='Part3' x:rel='#content.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY notation-abnf              "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY basic-rules                "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY uri                        "<xref target='Part1' x:rel='#uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY effective-request-uri      "<xref target='Part1' x:rel='#effective.request.uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY full-date                  "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY http-url                   "<xref target='Part1' x:rel='#http-url' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY http-version               "<xref target='Part1' x:rel='#http.version' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY use100                     "<xref target='Part1' x:rel='#use.of.the.100.status' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35  <!ENTITY qvalue                     "<xref target='Part3' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY request-target             "<xref target='Part1' x:rel='#request-target' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY header-accept              "<xref target='Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY header-accept-charset      "<xref target='Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY header-accept-encoding     "<xref target='Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY header-accept-language     "<xref target='Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41  <!ENTITY header-accept-ranges       "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
42  <!ENTITY header-age                 "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
43  <!ENTITY header-authorization       "<xref target='Part7' x:rel='#header.authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
44  <!ENTITY header-cache-control       "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
45  <!ENTITY header-content-location    "<xref target='Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
46  <!ENTITY header-content-range       "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
47  <!ENTITY header-etag                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
48  <!ENTITY header-expires             "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
49  <!ENTITY header-fields              "<xref target='Part1' x:rel='#header.fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
50  <!ENTITY header-host                "<xref target='Part1' x:rel='#header.host' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
51  <!ENTITY header-if-match            "<xref target='Part4' x:rel='#header.if-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
52  <!ENTITY header-if-modified-since   "<xref target='Part4' x:rel='#header.if-modified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
53  <!ENTITY header-if-none-match       "<xref target='Part4' x:rel='#header.if-none-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
54  <!ENTITY header-if-range            "<xref target='Part5' x:rel='#header.if-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
55  <!ENTITY header-if-unmodified-since "<xref target='Part4' x:rel='#header.if-unmodified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
56  <!ENTITY header-pragma              "<xref target='Part6' x:rel='#header.pragma' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
57  <!ENTITY header-proxy-authenticate  "<xref target='Part7' x:rel='#header.proxy-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
58  <!ENTITY header-proxy-authorization "<xref target='Part7' x:rel='#header.proxy-authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
59  <!ENTITY header-range               "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
60  <!ENTITY header-upgrade             "<xref target='Part1' x:rel='#header.upgrade' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
61  <!ENTITY header-te                  "<xref target='Part1' x:rel='#header.te' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
62  <!ENTITY header-vary                "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
63  <!ENTITY header-via                 "<xref target='Part1' x:rel='#header.via' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
64  <!ENTITY header-warning             "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
65  <!ENTITY header-www-authenticate    "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
66  <!ENTITY message-body               "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
67  <!ENTITY product-tokens             "<xref target='Part1' x:rel='#product.tokens' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
68  <!ENTITY media-type-message-http    "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
69  <!ENTITY status-206                 "<xref target='Part5' x:rel='#status.206' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
70  <!ENTITY status-304                 "<xref target='Part4' x:rel='#status.304' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
71  <!ENTITY status-401                 "<xref target='Part7' x:rel='#status.401' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
72  <!ENTITY status-407                 "<xref target='Part7' x:rel='#status.407' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
73  <!ENTITY status-412                 "<xref target='Part4' x:rel='#status.412' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
74  <!ENTITY status-416                 "<xref target='Part5' x:rel='#status.416' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
75  <!ENTITY p4-status-codes            "<xref target='Part4' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
76  <!ENTITY p5-status-codes            "<xref target='Part5' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
77  <!ENTITY p7-status-codes            "<xref target='Part7' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
78  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
79  <!ENTITY p6-explicit                "<xref target='Part6' x:rel='#calculating.freshness.lifetime' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
80  <!ENTITY p6-invalid                 "<xref target='Part6' x:rel='#invalidation.after.updates.or.deletions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
81]>
82<?rfc toc="yes" ?>
83<?rfc symrefs="yes" ?>
84<?rfc sortrefs="yes" ?>
85<?rfc compact="yes"?>
86<?rfc subcompact="no" ?>
87<?rfc linkmailto="no" ?>
88<?rfc editing="no" ?>
89<?rfc comments="yes"?>
90<?rfc inline="yes"?>
91<?rfc rfcedstyle="yes"?>
92<?rfc-ext allow-markup-in-artwork="yes" ?>
93<?rfc-ext include-references-in-index="yes" ?>
94<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
95     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
96     xmlns:x='http://purl.org/net/xml2rfc/ext'
97     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
98<front>
99
100  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
101
102  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
103    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
104    <address>
105      <postal>
106        <street>345 Park Ave</street>
107        <city>San Jose</city>
108        <region>CA</region>
109        <code>95110</code>
110        <country>USA</country>
111      </postal>
112      <email>fielding@gbiv.com</email>
113      <uri>http://roy.gbiv.com/</uri>
114    </address>
115  </author>
116
117  <author initials="J." surname="Gettys" fullname="Jim Gettys">
118    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
119    <address>
120      <postal>
121        <street>21 Oak Knoll Road</street>
122        <city>Carlisle</city>
123        <region>MA</region>
124        <code>01741</code>
125        <country>USA</country>
126      </postal>
127      <email>jg@freedesktop.org</email>
128      <uri>http://gettys.wordpress.com/</uri>
129    </address>
130  </author>
131 
132  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
133    <organization abbrev="HP">Hewlett-Packard Company</organization>
134    <address>
135      <postal>
136        <street>HP Labs, Large Scale Systems Group</street>
137        <street>1501 Page Mill Road, MS 1177</street>
138        <city>Palo Alto</city>
139        <region>CA</region>
140        <code>94304</code>
141        <country>USA</country>
142      </postal>
143      <email>JeffMogul@acm.org</email>
144    </address>
145  </author>
146
147  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
148    <organization abbrev="Microsoft">Microsoft Corporation</organization>
149    <address>
150      <postal>
151        <street>1 Microsoft Way</street>
152        <city>Redmond</city>
153        <region>WA</region>
154        <code>98052</code>
155        <country>USA</country>
156      </postal>
157      <email>henrikn@microsoft.com</email>
158    </address>
159  </author>
160
161  <author initials="L." surname="Masinter" fullname="Larry Masinter">
162    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
163    <address>
164      <postal>
165        <street>345 Park Ave</street>
166        <city>San Jose</city>
167        <region>CA</region>
168        <code>95110</code>
169        <country>USA</country>
170      </postal>
171      <email>LMM@acm.org</email>
172      <uri>http://larry.masinter.net/</uri>
173    </address>
174  </author>
175 
176  <author initials="P." surname="Leach" fullname="Paul J. Leach">
177    <organization abbrev="Microsoft">Microsoft Corporation</organization>
178    <address>
179      <postal>
180        <street>1 Microsoft Way</street>
181        <city>Redmond</city>
182        <region>WA</region>
183        <code>98052</code>
184      </postal>
185      <email>paulle@microsoft.com</email>
186    </address>
187  </author>
188   
189  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
190    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
191    <address>
192      <postal>
193        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
194        <street>The Stata Center, Building 32</street>
195        <street>32 Vassar Street</street>
196        <city>Cambridge</city>
197        <region>MA</region>
198        <code>02139</code>
199        <country>USA</country>
200      </postal>
201      <email>timbl@w3.org</email>
202      <uri>http://www.w3.org/People/Berners-Lee/</uri>
203    </address>
204  </author>
205
206  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
207    <organization abbrev="W3C">World Wide Web Consortium</organization>
208    <address>
209      <postal>
210        <street>W3C / ERCIM</street>
211        <street>2004, rte des Lucioles</street>
212        <city>Sophia-Antipolis</city>
213        <region>AM</region>
214        <code>06902</code>
215        <country>France</country>
216      </postal>
217      <email>ylafon@w3.org</email>
218      <uri>http://www.raubacapeu.net/people/yves/</uri>
219    </address>
220  </author>
221
222  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
223    <organization abbrev="greenbytes">greenbytes GmbH</organization>
224    <address>
225      <postal>
226        <street>Hafenweg 16</street>
227        <city>Muenster</city><region>NW</region><code>48155</code>
228        <country>Germany</country>
229      </postal>
230      <phone>+49 251 2807760</phone>
231      <facsimile>+49 251 2807761</facsimile>
232      <email>julian.reschke@greenbytes.de</email>
233      <uri>http://greenbytes.de/tech/webdav/</uri>
234    </address>
235  </author>
236
237  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
238  <workgroup>HTTPbis Working Group</workgroup>
239
240<abstract>
241<t>
242   The Hypertext Transfer Protocol (HTTP) is an application-level
243   protocol for distributed, collaborative, hypermedia information
244   systems. HTTP has been in use by the World Wide Web global information
245   initiative since 1990. This document is Part 2 of the seven-part specification
246   that defines the protocol referred to as "HTTP/1.1" and, taken together,
247   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
248   as expressed by request methods, request header fields, response status codes,
249   and response header fields.
250</t>
251</abstract>
252
253<note title="Editorial Note (To be removed by RFC Editor)">
254  <t>
255    Discussion of this draft should take place on the HTTPBIS working group
256    mailing list (ietf-http-wg@w3.org). The current issues list is
257    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/>
258    and related documents (including fancy diffs) can be found at
259    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
260  </t>
261  <t>
262    The changes in this draft are summarized in <xref target="changes.since.12"/>.
263  </t>
264</note>
265</front>
266<middle>
267<section title="Introduction" anchor="introduction">
268<t>
269   This document defines HTTP/1.1 request and response semantics.  Each HTTP
270   message, as defined in &messaging;, is in the form of either a request or
271   a response.  An HTTP server listens on a connection for HTTP requests and
272   responds to each request, in the order received on that connection, with
273   one or more HTTP response messages.  This document defines the commonly
274   agreed upon semantics of the HTTP uniform interface, the intentions defined
275   by each request method, and the various response messages that might be
276   expected as a result of applying that method to the target resource.
277</t>
278<t>
279   This document is currently disorganized in order to minimize the changes
280   between drafts and enable reviewers to see the smaller errata changes.
281   A future draft will reorganize the sections to better reflect the content.
282   In particular, the sections will be ordered according to the typical
283   processing of an HTTP request message (after message parsing): resource
284   mapping, methods, request modifying header fields, response status,
285   status modifying header fields, and resource metadata.  The current mess
286   reflects how widely dispersed these topics and associated requirements
287   had become in <xref target="RFC2616"/>.
288</t>
289
290<section title="Requirements" anchor="intro.requirements">
291<t>
292   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
293   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
294   document are to be interpreted as described in <xref target="RFC2119"/>.
295</t>
296<t>
297   An implementation is not compliant if it fails to satisfy one or more
298   of the "MUST" or "REQUIRED" level requirements for the protocols it
299   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
300   level and all the "SHOULD" level requirements for its protocols is said
301   to be "unconditionally compliant"; one that satisfies all the "MUST"
302   level requirements but not all the "SHOULD" level requirements for its
303   protocols is said to be "conditionally compliant".
304</t>
305</section>
306
307<section title="Syntax Notation" anchor="notation">
308  <x:anchor-alias value="CR"/>
309  <x:anchor-alias value="DIGIT"/>
310  <x:anchor-alias value="LF"/>
311  <x:anchor-alias value="VCHAR"/>
312  <x:anchor-alias value="WSP"/>
313<t>
314  This specification uses the ABNF syntax defined in &notation; (which
315  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
316  <xref target="collected.abnf"/> shows the collected ABNF, with the list
317  rule expanded.
318</t>
319<t>
320  The following core rules are included by
321  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
322  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
323  DIGIT (decimal 0-9), DQUOTE (double quote),
324  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
325  OCTET (any 8-bit sequence of data), SP (space),
326  VCHAR (any visible USASCII character),
327  and WSP (whitespace).
328</t>
329
330<section title="Core Rules" anchor="core.rules">
331  <x:anchor-alias value="obs-text"/>
332  <x:anchor-alias value="quoted-string"/>
333  <x:anchor-alias value="token"/>
334  <x:anchor-alias value="OWS"/>
335  <x:anchor-alias value="RWS"/>
336<t>
337  The core rules below are defined in &basic-rules;:
338</t>
339<figure><artwork type="abnf2616">
340  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
341  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
342  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
343  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
344  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
345</artwork></figure>
346</section>
347
348<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
349  <x:anchor-alias value="absolute-URI"/>
350  <x:anchor-alias value="comment"/>
351  <x:anchor-alias value="HTTP-date"/>
352  <x:anchor-alias value="partial-URI"/>
353  <x:anchor-alias value="product"/>
354  <x:anchor-alias value="URI-reference"/>
355<t>
356  The ABNF rules below are defined in other parts:
357</t>
358<figure><!--Part1--><artwork type="abnf2616">
359  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
360  <x:ref>comment</x:ref>       = &lt;comment, defined in &header-fields;&gt;
361  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
362  <x:ref>partial-URI</x:ref>   = &lt;partial-URI, defined in &uri;&gt;
363  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
364  <x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in &uri;&gt;
365</artwork></figure>
366</section>
367</section>
368</section>
369
370<section title="Method" anchor="method">
371  <x:anchor-alias value="Method"/>
372  <x:anchor-alias value="extension-method"/>
373<t>
374   The Method token indicates the request method to be performed on the target
375   resource (&effective-request-uri;). The method is case-sensitive.
376</t>
377<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/>
378  <x:ref>Method</x:ref>         = <x:ref>token</x:ref>
379</artwork></figure>
380<t>
381   The list of methods allowed by a resource can be specified in an
382   Allow header field (<xref target="header.allow"/>). The status code of the response
383   always notifies the client whether a method is currently allowed on a
384   resource, since the set of allowed methods can change dynamically. An
385   origin server &SHOULD; respond with the status code 405 (Method Not Allowed)
386   if the method is known by the origin server but not allowed for the
387   resource, and 501 (Not Implemented) if the method is
388   unrecognized or not implemented by the origin server. The methods GET
389   and HEAD &MUST; be supported by all general-purpose servers. All other
390   methods are &OPTIONAL;; however, if the above methods are implemented,
391   they &MUST; be implemented with the same semantics as those specified
392   in <xref target="method.definitions"/>.
393</t>
394
395<section title="Overview of Methods" anchor="overview.of.methods">
396<t>
397  The methods listed below are defined in <xref target="method.definitions"/>.
398</t>
399<texttable align="left">
400  <ttcol>Method Name</ttcol><ttcol>Defined in...</ttcol>
401 
402  <c>OPTIONS</c> <c><xref target="OPTIONS"/></c>
403  <c>GET</c> <c><xref target="GET"/></c>
404  <c>HEAD</c> <c><xref target="HEAD"/></c>
405  <c>POST</c> <c><xref target="POST"/></c>
406  <c>PUT</c> <c><xref target="PUT"/></c>
407  <c>DELETE</c> <c><xref target="DELETE"/></c>
408  <c>TRACE</c> <c><xref target="TRACE"/></c>
409  <c>CONNECT</c> <c><xref target="CONNECT"/></c>
410</texttable>
411<t>
412  Note that this list is not exhaustive &mdash; it does not include request methods defined
413  in other specifications.
414</t>
415</section>
416
417<section title="Method Registry" anchor="method.registry">
418<t>
419  The HTTP Method Registry defines the name space for the Method token in the
420  Request line of an HTTP request.
421</t>
422<t>
423  Registrations &MUST; include the following fields:
424  <list style="symbols">
425    <t>Method Name (see <xref target="method"/>)</t>
426    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
427    <t>Pointer to specification text</t>
428  </list>
429</t>
430<t>
431  Values to be added to this name space are subject to IETF review
432  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
433</t>
434<t>
435  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
436</t>
437
438<section title="Considerations for New Methods" anchor="considerations.for.new.methods">
439<t>
440   When it is necessary to express new semantics for a HTTP request that
441   aren't specific to a single application or media type, and currently defined
442   methods are inadequate, it may be appropriate to register a new method.
443</t>
444<t>
445   HTTP methods are generic; that is, they are potentially applicable to any
446   resource, not just one particular media type, "type" of resource, or
447   application. As such, it is preferred that new HTTP methods be registered
448   in a document that isn't specific to a single application, so that this is
449   clear.
450</t>
451<t>
452   Due to the parsing rules defined in &message-body;, definitions of HTTP
453   methods cannot prohibit the presence of a message-body on either the request
454   or the response message (with responses to HEAD requests being the single
455   exception). Definitions of new methods cannot change this rule, but they can
456   specify that only zero-length bodies (as opposed to absent bodies) are allowed.
457</t>
458<t>
459   New method definitions need to indicate whether they are safe (<xref
460   target="safe.methods"/>) and whether they are idempotent (<xref
461   target="idempotent.methods"/>). They also need to state whether they can be
462   cached (&caching;); in particular what conditions a cache may store the
463   response, and under what conditions such a stored response may be used to
464   satisfy a subsequent request.
465</t>
466</section>
467
468</section>
469</section>
470
471<section title="Request Header Fields" anchor="request.header.fields">
472  <x:anchor-alias value="request-header"/>
473<t>
474   The request header fields allow the client to pass additional
475   information about the request, and about the client itself, to the
476   server. These fields act as request modifiers, with semantics
477   equivalent to the parameters on a programming language method
478   invocation.
479</t>
480<texttable align="left">
481  <ttcol>Header Field Name</ttcol>
482  <ttcol>Defined in...</ttcol>
483
484  <c>Accept</c> <c>&header-accept;</c>
485  <c>Accept-Charset</c> <c>&header-accept-charset;</c>
486  <c>Accept-Encoding</c> <c>&header-accept-encoding;</c>
487  <c>Accept-Language</c> <c>&header-accept-language;</c>
488  <c>Authorization</c> <c>&header-authorization;</c>
489  <c>Expect</c> <c><xref target="header.expect"/></c>
490  <c>From</c> <c><xref target="header.from"/></c>
491  <c>Host</c> <c>&header-host;</c>
492  <c>If-Match</c> <c>&header-if-match;</c>
493  <c>If-Modified-Since</c> <c>&header-if-modified-since;</c>
494  <c>If-None-Match</c> <c>&header-if-none-match;</c>
495  <c>If-Range</c> <c>&header-if-range;</c>
496  <c>If-Unmodified-Since</c> <c>&header-if-unmodified-since;</c>
497  <c>Max-Forwards</c> <c><xref target="header.max-forwards"/></c>
498  <c>Proxy-Authorization</c> <c>&header-proxy-authorization;</c>
499  <c>Range</c> <c>&header-range;</c>
500  <c>Referer</c> <c><xref target="header.referer"/></c>
501  <c>TE</c> <c>&header-te;</c>
502  <c>User-Agent</c> <c><xref target="header.user-agent"/></c>
503</texttable>
504</section>
505
506<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
507  <x:anchor-alias value="Reason-Phrase"/>
508  <x:anchor-alias value="Status-Code"/>
509  <x:anchor-alias value="extension-code"/>
510<t>
511   The Status-Code element is a 3-digit integer result code of the attempt to
512   understand and satisfy the request.
513</t>
514<t>
515   The Reason-Phrase is intended to give a short textual description of the
516   Status-Code and is intended for a human user. The client does not need
517   to examine or display the Reason-Phrase.
518</t>
519<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"/>
520  <x:ref>Status-Code</x:ref>    = 3<x:ref>DIGIT</x:ref>
521  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
522</artwork></figure>
523<t>
524   HTTP status codes are extensible. HTTP applications are not required
525   to understand the meaning of all registered status codes, though such
526   understanding is obviously desirable. However, applications &MUST;
527   understand the class of any status code, as indicated by the first
528   digit, and treat any unrecognized response as being equivalent to the
529   x00 status code of that class, with the exception that an
530   unrecognized response &MUST-NOT; be cached. For example, if an
531   unrecognized status code of 431 is received by the client, it can
532   safely assume that there was something wrong with its request and
533   treat the response as if it had received a 400 status code. In such
534   cases, user agents &SHOULD; present to the user the representation enclosed
535   with the response, since that representation is likely to include human-readable
536   information which will explain the unusual status.
537</t>
538
539<section title="Overview of Status Codes" anchor="overview.of.status.codes">
540<t> 
541   The status codes listed below are defined in <xref target="status.codes"/>
542   of this specification, &p4-status-codes;, &p5-status-codes;, and &p7-status-codes;.
543   The reason phrases listed here are only recommendations &mdash; they can be
544   replaced by local equivalents without affecting the protocol.
545</t>
546<texttable align="left">
547  <ttcol>Status-Code</ttcol>
548  <ttcol>Reason-Phrase</ttcol>
549  <ttcol>Defined in...</ttcol>
550 
551  <c>100</c> <c>Continue</c> <c><xref target="status.100"/></c>
552  <c>101</c> <c>Switching Protocols</c> <c><xref target="status.101"/></c>
553
554  <c>200</c> <c>OK</c> <c><xref target="status.200"/></c>
555  <c>201</c> <c>Created</c> <c><xref target="status.201"/></c>
556  <c>202</c> <c>Accepted</c> <c><xref target="status.202"/></c>
557  <c>203</c> <c>Non-Authoritative Information</c> <c><xref target="status.203"/></c>
558  <c>204</c> <c>No Content</c> <c><xref target="status.204"/></c>
559  <c>205</c> <c>Reset Content</c> <c><xref target="status.205"/></c>
560  <c>206</c> <c>Partial Content</c> <c>&status-206;</c>
561
562  <c>300</c> <c>Multiple Choices</c> <c><xref target="status.300"/></c>
563  <c>301</c> <c>Moved Permanently</c> <c><xref target="status.301"/></c>
564  <c>302</c> <c>Found</c> <c><xref target="status.302"/></c>
565  <c>303</c> <c>See Other</c> <c><xref target="status.303"/></c>
566  <c>304</c> <c>Not Modified</c> <c>&status-304;</c>
567  <c>305</c> <c>Use Proxy</c> <c><xref target="status.305"/></c>
568  <c>307</c> <c>Temporary Redirect</c> <c><xref target="status.307"/></c>
569
570  <c>400</c> <c>Bad Request</c> <c><xref target="status.400"/></c>
571  <c>401</c> <c>Unauthorized</c> <c>&status-401;</c>
572  <c>402</c> <c>Payment Required</c> <c><xref target="status.402"/></c>
573  <c>403</c> <c>Forbidden</c> <c><xref target="status.403"/></c>
574  <c>404</c> <c>Not Found</c> <c><xref target="status.404"/></c>
575  <c>405</c> <c>Method Not Allowed</c> <c><xref target="status.405"/></c>
576  <c>406</c> <c>Not Acceptable</c> <c><xref target="status.406"/></c>
577  <c>407</c> <c>Proxy Authentication Required</c> <c>&status-407;</c>
578  <c>408</c> <c>Request Time-out</c> <c><xref target="status.408"/></c>
579  <c>409</c> <c>Conflict</c> <c><xref target="status.409"/></c>
580  <c>410</c> <c>Gone</c> <c><xref target="status.410"/></c>
581  <c>411</c> <c>Length Required</c> <c><xref target="status.411"/></c>
582  <c>412</c> <c>Precondition Failed</c> <c>&status-412;</c>
583  <c>413</c> <c>Request Entity Too Large</c> <c><xref target="status.413"/></c>
584  <c>414</c> <c>URI Too Long</c> <c><xref target="status.414"/></c>
585  <c>415</c> <c>Unsupported Media Type</c> <c><xref target="status.415"/></c>
586  <c>416</c> <c>Requested range not satisfiable</c> <c>&status-416;</c>
587  <c>417</c> <c>Expectation Failed</c> <c><xref target="status.417"/></c>
588  <c>426</c> <c>Upgrade Required</c> <c><xref target="status.426"/></c>
589
590  <c>500</c> <c>Internal Server Error</c> <c><xref target="status.500"/></c>
591  <c>501</c> <c>Not Implemented</c> <c><xref target="status.501"/></c>
592  <c>502</c> <c>Bad Gateway</c> <c><xref target="status.502"/></c>
593  <c>503</c> <c>Service Unavailable</c> <c><xref target="status.503"/></c>
594  <c>504</c> <c>Gateway Time-out</c> <c><xref target="status.504"/></c>
595  <c>505</c> <c>HTTP Version not supported</c> <c><xref target="status.505"/></c>
596</texttable>
597<t>
598   Note that this list is not exhaustive &mdash; it does not include
599   extension status codes defined in other specifications.
600</t>
601</section>
602
603<section title="Status Code Registry" anchor="status.code.registry">
604<t>
605  The HTTP Status Code Registry defines the name space for the Status-Code
606  token in the Status-Line of an HTTP response.
607</t>
608<t>
609  Values to be added to this name space are subject to IETF review
610  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
611</t>
612<t>
613  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
614</t>
615
616<section title="Considerations for New Status Codes" anchor="considerations.for.new.status.codes">
617<t>
618   When it is necessary to express new semantics for a HTTP response that
619   aren't specific to a single application or media type, and currently defined
620   status codes are inadequate, a new status code can be registered.
621</t>
622<t>
623   HTTP status codes are generic; that is, they are potentially applicable to
624   any resource, not just one particular media type, "type" of resource, or
625   application. As such, it is preferred that new HTTP status codes be
626   registered in a document that isn't specific to a single application, so
627   that this is clear.
628</t>
629<t>
630   Definitions of new HTTP status codes typically explain the request
631   conditions that produce a response containing the status code (e.g.,
632   combinations of request headers and/or method(s)), along with any
633   interactions with response headers (e.g., those that are required, those
634   that modify the semantics of the response).
635</t>
636<t>
637   New HTTP status codes are required to fall under one of the categories
638   defined in <xref target="status.codes"/>. To allow existing parsers to
639   properly handle them, new status codes cannot disallow a response body,
640   although they can mandate a zero-length response body. They can require the
641   presence of one or more particular HTTP response header(s).
642</t>
643<t>
644   Likewise, their definitions can specify that caches are allowed to use
645   heuristics to determine their freshness (see &caching;; by default, it is
646   not allowed), and can define how to determine the resource which they
647   carry a representation for (see <xref
648   target="identifying.response.associated.with.representation"/>; by default,
649   it is anonymous).
650</t>
651</section>
652
653</section>
654
655</section>
656
657<section title="Response Header Fields" anchor="response.header.fields">
658  <x:anchor-alias value="response-header"/>
659<t>
660   The response header fields allow the server to pass additional
661   information about the response which cannot be placed in the Status-Line.
662   These header fields give information about the server and about
663   further access to the target resource (&effective-request-uri;).
664</t>
665<texttable align="left">
666  <ttcol>Header Field Name</ttcol><ttcol>Defined in...</ttcol>
667
668  <c>Accept-Ranges</c> <c>&header-accept-ranges;</c>
669  <c>Age</c> <c>&header-age;</c>
670  <c>Allow</c> <c><xref target="header.allow"/></c>
671  <c>ETag</c> <c>&header-etag;</c>
672  <c>Location</c> <c><xref target="header.location"/></c>
673  <c>Proxy-Authenticate</c> <c>&header-proxy-authenticate;</c>
674  <c>Retry-After</c> <c><xref target="header.retry-after"/></c>
675  <c>Server</c> <c><xref target="header.server"/></c>
676  <c>Vary</c> <c>&header-vary;</c>
677  <c>WWW-Authenticate</c> <c>&header-www-authenticate;</c>
678</texttable>
679</section>
680
681<section title="Representation" anchor="representation">
682<t>
683   Request and Response messages &MAY; transfer a representation if not otherwise
684   restricted by the request method or response status code. A representation
685   consists of metadata (representation header fields) and data (representation
686   body).  When a complete or partial representation is enclosed in an HTTP message,
687   it is referred to as the payload of the message. HTTP representations
688   are defined in &payload;.
689</t>
690<t>
691   A representation body is only present in a message when a message-body is
692   present, as described in &message-body;. The representation body is obtained
693   from the message-body by decoding any Transfer-Encoding that might
694   have been applied to ensure safe and proper transfer of the message.
695</t>
696
697<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
698<t>
699   It is sometimes necessary to determine an identifier for the resource
700   associated with a representation.
701</t>
702<t>
703   An HTTP request representation, when present, is always associated with an
704   anonymous (i.e., unidentified) resource.
705</t>
706<t>
707   In the common case, an HTTP response is a representation of the target
708   resource (see &effective-request-uri;). However, this is not always the
709   case. To determine the URI of the resource a response is associated with,
710   the following rules are used (with the first applicable one being selected):
711</t>
712<t><list style="numbers">
713   <t>If the response status code is 200 or 203 and the request method was GET,
714   the response payload is a representation of the target resource.</t>
715   <t>If the response status code is 204, 206, or 304 and the request method was GET
716   or HEAD, the response payload is a partial representation of the target
717   resource (see &combining-responses;).</t>
718   <t>If the response has a Content-Location header field, and that URI is the same
719   as the effective request URI, the response payload is a representation of the
720   target resource.</t>
721   <t>If the response has a Content-Location header field, and that URI is not the
722   same as the effective request URI, then the response asserts that its
723   payload is a representation of the resource identified by the
724   Content-Location URI. However, such an assertion cannot be trusted unless
725   it can be verified by other means (not defined by HTTP).</t>
726   <t>Otherwise, the response is a representation of an anonymous (i.e.,
727   unidentified) resource.</t>
728</list></t>
729<t>
730  <cref anchor="TODO-req-uri">
731   The comparison function is going to have to be defined somewhere,
732   because we already need to compare URIs for things like cache invalidation.</cref>
733</t>
734</section>
735
736</section>
737
738
739<section title="Method Definitions" anchor="method.definitions">
740<t>
741   The set of common request methods for HTTP/1.1 is defined below. Although
742   this set can be expanded, additional methods cannot be assumed to
743   share the same semantics for separately extended clients and servers.
744</t>
745
746<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
747
748<section title="Safe Methods" anchor="safe.methods">
749<iref item="Safe Methods" primary="true"/>
750<t>
751   Implementors need to be aware that the software represents the user in
752   their interactions over the Internet, and need to allow
753   the user to be aware of any actions they take which might have an
754   unexpected significance to themselves or others.
755</t>
756<t>
757   In particular, the convention has been established that the GET, HEAD,
758   OPTIONS, and TRACE request methods &SHOULD-NOT; have the significance
759   of taking an action other than retrieval. These request methods ought
760   to be considered "<x:dfn anchor="safe">safe</x:dfn>".
761   This allows user agents to represent other methods, such as POST, PUT
762   and DELETE, in a special way, so that the user is made aware of the
763   fact that a possibly unsafe action is being requested.
764</t>
765<t>
766   Naturally, it is not possible to ensure that the server does not
767   generate side-effects as a result of performing a GET request; in
768   fact, some dynamic resources consider that a feature. The important
769   distinction here is that the user did not request the side-effects,
770   so therefore cannot be held accountable for them.
771</t>
772</section>
773
774<section title="Idempotent Methods" anchor="idempotent.methods">
775<iref item="Idempotent Methods" primary="true"/>
776<t>
777   Request methods can also have the property of "idempotence" in that,
778   aside from error or expiration issues, the intended effect of multiple
779   identical requests is the same as for a single request.
780   PUT, DELETE, and all safe request methods are idempotent.
781   It is important to note that idempotence refers only to changes
782   requested by the client: a server is free to change its state due
783   to multiple requests for the purpose of tracking those requests,
784   versioning of results, etc.
785</t>
786</section>
787</section>
788
789<section title="OPTIONS" anchor="OPTIONS">
790  <rdf:Description>
791    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
792  </rdf:Description>
793  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
794  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
795<t>
796   The OPTIONS method requests information about the
797   communication options available on the request/response chain
798   identified by the effective request URI. This method allows a client to
799   determine the options and/or requirements associated with a resource,
800   or the capabilities of a server, without implying a resource action
801   or initiating a resource retrieval.
802</t>
803<t>
804   Responses to the OPTIONS method are not cacheable.
805</t>
806<t>
807   If the OPTIONS request includes a message-body (as indicated by the
808   presence of Content-Length or Transfer-Encoding), then the media type
809   &MUST; be indicated by a Content-Type field. Although this
810   specification does not define any use for such a body, future
811   extensions to HTTP might use the OPTIONS body to make more detailed
812   queries on the server.
813</t>
814<t>
815   If the request-target is an asterisk ("*"), the OPTIONS request is
816   intended to apply to the server in general rather than to a specific
817   resource. Since a server's communication options typically depend on
818   the resource, the "*" request is only useful as a "ping" or "no-op"
819   type of method; it does nothing beyond allowing the client to test
820   the capabilities of the server. For example, this can be used to test
821   a proxy for HTTP/1.1 compliance (or lack thereof).
822</t>
823<t>
824   If the request-target is not an asterisk, the OPTIONS request applies
825   only to the options that are available when communicating with that
826   resource.
827</t>
828<t>
829   A 200 response &SHOULD; include any header fields that indicate
830   optional features implemented by the server and applicable to that
831   resource (e.g., Allow), possibly including extensions not defined by
832   this specification. The response body, if any, &SHOULD; also include
833   information about the communication options. The format for such a
834   body is not defined by this specification, but might be defined by
835   future extensions to HTTP. Content negotiation &MAY; be used to select
836   the appropriate response format. If no response body is included, the
837   response &MUST; include a Content-Length field with a field-value of
838   "0".
839</t>
840<t>
841   The Max-Forwards header field &MAY; be used to target a
842   specific proxy in the request chain (see <xref target="header.max-forwards"/>).
843   If no Max-Forwards field is present in the request, then the forwarded
844   request &MUST-NOT; include a Max-Forwards field.
845</t>
846</section>
847
848<section title="GET" anchor="GET">
849  <rdf:Description>
850    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
851  </rdf:Description>
852  <iref primary="true" item="GET method" x:for-anchor=""/>
853  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
854<t>
855   The GET method requests transfer of a current representation of
856   the target resource.
857</t>
858<t>   
859   If the target resource is a data-producing process, it is the
860   produced data which shall be returned as the representation in the response and not
861   the source text of the process, unless that text happens to be the output of
862   the process.
863</t>
864<t>
865   The semantics of the GET method change to a "conditional GET" if the
866   request message includes an If-Modified-Since, If-Unmodified-Since,
867   If-Match, If-None-Match, or If-Range header field. A conditional GET
868   requests that the representation be transferred only under the
869   circumstances described by the conditional header field(s). The
870   conditional GET request is intended to reduce unnecessary network
871   usage by allowing cached representations to be refreshed without requiring
872   multiple requests or transferring data already held by the client.
873</t>
874<t>
875   The semantics of the GET method change to a "partial GET" if the
876   request message includes a Range header field. A partial GET requests
877   that only part of the representation be transferred, as described in &header-range;.
878   The partial GET request is intended to reduce unnecessary
879   network usage by allowing partially-retrieved representations to be
880   completed without transferring data already held by the client.
881</t>
882<t>
883   The response to a GET request is cacheable and &MAY; be used to satisfy
884   subsequent GET and HEAD requests (see &caching;).
885</t>
886<t>
887   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
888</t>
889</section>
890
891<section title="HEAD" anchor="HEAD">
892  <rdf:Description>
893    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
894  </rdf:Description>
895  <iref primary="true" item="HEAD method" x:for-anchor=""/>
896  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
897<t>
898   The HEAD method is identical to GET except that the server &MUST-NOT;
899   return a message-body in the response. The metadata contained
900   in the HTTP header fields in response to a HEAD request &SHOULD; be identical
901   to the information sent in response to a GET request. This method can
902   be used for obtaining metadata about the representation implied by the
903   request without transferring the representation body. This method is
904   often used for testing hypertext links for validity, accessibility,
905   and recent modification.
906</t>
907<t>
908   The response to a HEAD request is cacheable and &MAY; be used to satisfy
909   a subsequent HEAD request; see &caching;. It also &MAY; be used to update a previously cached
910   representation from that resource; if the new field values
911   indicate that the cached representation differs from the current representation (as
912   would be indicated by a change in Content-Length, Content-MD5, ETag
913   or Last-Modified), then the cache &MUST; treat the cache entry as
914   stale.
915</t>
916</section>
917
918<section title="POST" anchor="POST">
919  <iref primary="true" item="POST method" x:for-anchor=""/>
920  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
921<t>
922   The POST method requests that the origin server accept the
923   representation enclosed in the request as data to be processed by the
924   target resource. POST is designed to allow a uniform method to cover the
925   following functions:
926  <list style="symbols">
927    <t>
928      Annotation of existing resources;
929    </t>
930    <t>
931        Posting a message to a bulletin board, newsgroup, mailing list,
932        or similar group of articles;
933    </t>
934    <t>
935        Providing a block of data, such as the result of submitting a
936        form, to a data-handling process;
937    </t>
938    <t>
939        Extending a database through an append operation.
940    </t>
941  </list>
942</t>
943<t>
944   The actual function performed by the POST method is determined by the
945   server and is usually dependent on the effective request URI.
946</t>
947<t>
948   The action performed by the POST method might not result in a
949   resource that can be identified by a URI. In this case, either 200
950   (OK) or 204 (No Content) is the appropriate response status code,
951   depending on whether or not the response includes a representation that
952   describes the result.
953</t>
954<t>
955   If a resource has been created on the origin server, the response
956   &SHOULD; be 201 (Created) and contain a representation which describes the
957   status of the request and refers to the new resource, and a Location
958   header field (see <xref target="header.location"/>).
959</t>
960<t>
961   Responses to POST requests are only cacheable when they
962   include explicit freshness information (see &p6-explicit;). A
963   cached POST response with a Content-Location header field
964   (see &header-content-location;) whose value is the effective
965   Request URI &MAY; be used to satisfy subsequent GET and HEAD requests.
966</t>
967<t>
968   Note that POST caching is not widely implemented.
969   However, the 303 (See Other) response can be used to direct the
970   user agent to retrieve a cacheable resource.
971</t>
972</section>
973
974<section title="PUT" anchor="PUT">
975  <iref primary="true" item="PUT method" x:for-anchor=""/>
976  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
977<t>
978   The PUT method requests that the state of the target resource
979   be created or replaced with the state defined by the representation
980   enclosed in the request message payload.  A successful PUT of a given
981   representation would suggest that a subsequent GET on that same target
982   resource will result in an equivalent representation being returned in
983   a 200 (OK) response.  However, there is no guarantee that such a state
984   change will be observable, since the target resource might be acted
985   upon by other user agents in parallel, or might be subject to dynamic
986   processing by the origin server, before any subsequent GET is received.
987   A successful response only implies that the user agent's intent was
988   achieved at the time of its processing by the origin server.
989</t>
990<t>   
991   If the target resource does not have a current representation and
992   the PUT successfully creates one, then the origin server &MUST; inform
993   the user agent by sending a 201 (Created) response.  If the target
994   resource does have a current representation and that representation is
995   successfully modified in accordance with the state of the enclosed
996   representation, then either a 200 (OK) or 204 (No Content) response
997   &SHOULD; be sent to indicate successful completion of the request.
998</t>
999<t>
1000   Unrecognized header fields &SHOULD; be ignored (i.e., not saved
1001   as part of the resource state).
1002</t>
1003<t>
1004   An origin server &SHOULD; verify that the PUT representation is
1005   consistent with any constraints which the server has for the target
1006   resource that cannot or will not be changed by the PUT.  This is
1007   particularly important when the origin server uses internal
1008   configuration information related to the URI in order to set the
1009   values for representation metadata on GET responses.  When a PUT
1010   representation is inconsistent with the target resource, the origin
1011   server &SHOULD; either make them consistent, by transforming the
1012   representation or changing the resource configuration, or respond
1013   with a 409 (Conflict) status code and sufficient information
1014   to explain why the representation is unsuitable.
1015</t>
1016<t>
1017   For example, if the target resource is configured to always have a
1018   Content-Type of "text/html" and the representation being PUT has a
1019   Content-Type of "image/jpeg", then the origin server &SHOULD; do one of:
1020   (a) reconfigure the target resource to reflect the new media type;
1021   (b) transform the PUT representation to a format consistent with that
1022   of the resource before saving it as the new resource state; or,
1023   (c) reject the request with a 409 response indicating that the target
1024   resource is limited to "text/html", perhaps including a link to a
1025   different resource that would be a suitable target for the new
1026   representation.
1027</t>
1028<t>
1029   HTTP does not define exactly how a PUT method affects the state
1030   of an origin server beyond what can be expressed by the intent of
1031   the user agent request and the semantics of the origin server response.
1032   It does not define what a resource might be, in any sense of that
1033   word, beyond the interface provided via HTTP.  It does not define
1034   how resource state is "stored", nor how such storage might change
1035   as a result of a change in resource state, nor how the origin server
1036   translates resource state into representations.  Generally speaking,
1037   all implementation details behind the resource interface are
1038   intentionally hidden by the server.
1039</t>
1040<t>
1041   The fundamental difference between the POST and PUT methods is
1042   highlighted by the different intent for the target resource.
1043   The target resource in a POST request is intended to handle the
1044   enclosed representation as a data-accepting process, such as for
1045   a gateway to some other protocol or a document that accepts annotations.
1046   In contrast, the target resource in a PUT request is intended to
1047   take the enclosed representation as a new or replacement value.
1048   Hence, the intent of PUT is idempotent and visible to intermediaries,
1049   even though the exact effect is only known by the origin server.
1050</t>
1051<t>
1052   Proper interpretation of a PUT request presumes that the user agent
1053   knows what target resource is desired.  A service that is intended
1054   to select a proper URI on behalf of the client, after receiving
1055   a state-changing request, &SHOULD; be implemented using the POST
1056   method rather than PUT.  If the origin server will not make the
1057   requested PUT state change to the target resource and instead
1058   wishes to have it applied to a different resource, such as when the
1059   resource has been moved to a different URI, then the origin server
1060   &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
1061   then make its own decision regarding whether or not to redirect the
1062   request.
1063</t>
1064<t>
1065   A PUT request applied to the target resource &MAY; have side-effects
1066   on other resources.  For example, an article might have a URI for
1067   identifying "the current version" (a resource) which is separate
1068   from the URIs identifying each particular version (different
1069   resources that at one point shared the same state as the current version
1070   resource).  A successful PUT request on "the current version" URI might
1071   therefore create a new version resource in addition to changing the
1072   state of the target resource, and might also cause links to be added
1073   between the related resources.
1074</t>
1075<t>
1076   An origin server &SHOULD; reject any PUT request that contains a
1077   Content-Range header field, since it might be misinterpreted as
1078   partial content (or might be partial content that is being mistakenly
1079   PUT as a full representation).  Partial content updates are
1080   possible by targeting a separately identified resource with state
1081   that overlaps a portion of the larger resource, or by using a
1082   different method that has been specifically defined for partial
1083   updates (for example, the PATCH method defined in
1084   <xref target="RFC5789"/>).
1085</t>
1086<t>
1087   Responses to the PUT method are not cacheable. If a PUT request passes
1088   through a cache that has one or more stored responses for the effective
1089   request URI, those stored responses will be invalidated (see
1090   &p6-invalid;).
1091</t>
1092</section>
1093
1094<section title="DELETE" anchor="DELETE">
1095  <iref primary="true" item="DELETE method" x:for-anchor=""/>
1096  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
1097<t>
1098   The DELETE method requests that the origin server delete the target
1099   resource. This method &MAY; be overridden by
1100   human intervention (or other means) on the origin server. The client cannot
1101   be guaranteed that the operation has been carried out, even if the
1102   status code returned from the origin server indicates that the action
1103   has been completed successfully. However, the server &SHOULD-NOT; 
1104   indicate success unless, at the time the response is given, it
1105   intends to delete the resource or move it to an inaccessible
1106   location.
1107</t>
1108<t>
1109   A successful response &SHOULD; be 200 (OK) if the response includes an
1110   representation describing the status, 202 (Accepted) if the action has not
1111   yet been enacted, or 204 (No Content) if the action has been enacted
1112   but the response does not include a representation.
1113</t>
1114<t>
1115   Responses to the DELETE method are not cacheable. If a DELETE request
1116   passes through a cache that has one or more stored responses for the
1117   effective request URI, those stored responses will be invalidated (see
1118   &p6-invalid;).
1119</t>
1120</section>
1121
1122<section title="TRACE" anchor="TRACE">
1123  <rdf:Description>
1124    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1125  </rdf:Description>
1126  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1127  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1128<t>
1129   The TRACE method requests a remote, application-layer loop-back
1130   of the request message. The final recipient of the request
1131   &SHOULD; reflect the message received back to the client as the
1132   message-body of a 200 (OK) response. The final recipient is either the
1133   origin server or the first proxy or gateway to receive a Max-Forwards
1134   value of zero (0) in the request (see <xref target="header.max-forwards"/>).
1135   A TRACE request &MUST-NOT; include a message-body.
1136</t>
1137<t>
1138   TRACE allows the client to see what is being received at the other
1139   end of the request chain and use that data for testing or diagnostic
1140   information. The value of the Via header field (&header-via;) is of
1141   particular interest, since it acts as a trace of the request chain.
1142   Use of the Max-Forwards header field allows the client to limit the
1143   length of the request chain, which is useful for testing a chain of
1144   proxies forwarding messages in an infinite loop.
1145</t>
1146<t>
1147   If the request is valid, the response &SHOULD; have a Content-Type of
1148   "message/http" (see &media-type-message-http;) and contain a message-body
1149   that encloses a copy of the entire request message.
1150   Responses to the TRACE method are not cacheable.
1151</t>
1152</section>
1153
1154<section title="CONNECT" anchor="CONNECT">
1155  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1156  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1157<t>
1158   The CONNECT method requests that the proxy establish a tunnel
1159   to the request-target and then restrict its behavior to blind
1160   forwarding of packets until the connection is closed.
1161</t>
1162<t>
1163   When using CONNECT, the request-target &MUST; use the authority form
1164   (&request-target;); i.e., the request-target consists of only the
1165   host name and port number of the tunnel destination, separated by a colon.
1166   For example,
1167</t>
1168<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1169CONNECT server.example.com:80 HTTP/1.1
1170Host: server.example.com:80
1171
1172</artwork></figure>
1173<t>
1174   Other HTTP mechanisms can be used normally with the CONNECT method &mdash;
1175   except end-to-end protocol Upgrade requests, since the
1176   tunnel must be established first.
1177</t>
1178<t>
1179   For example, proxy authentication might be used to establish the
1180   authority to create a tunnel:
1181</t>
1182<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1183CONNECT server.example.com:80 HTTP/1.1
1184Host: server.example.com:80
1185Proxy-Authorization: basic aGVsbG86d29ybGQ=
1186
1187</artwork></figure>
1188<t>
1189   Like any other pipelined HTTP/1.1 request, data to be tunnel may be
1190   sent immediately after the blank line. The usual caveats also apply:
1191   data may be discarded if the eventual response is negative, and the
1192   connection may be reset with no response if more than one TCP segment
1193   is outstanding.
1194</t>
1195
1196<section title="Establishing a Tunnel with CONNECT">
1197<t>
1198   Any successful (2xx) response to a CONNECT request indicates that the
1199   proxy has established a connection to the requested host and port,
1200   and has switched to tunneling the current connection to that server
1201   connection.
1202</t>
1203<t>
1204   It may be the case that the proxy itself can only reach the requested
1205   origin server through another proxy.  In this case, the first proxy
1206   &SHOULD; make a CONNECT request of that next proxy, requesting a tunnel
1207   to the authority.  A proxy &MUST-NOT; respond with any 2xx status code
1208   unless it has either a direct or tunnel connection established to the
1209   authority.
1210</t>
1211<t>
1212   An origin server which receives a CONNECT request for itself &MAY;
1213   respond with a 2xx status code to indicate that a connection is
1214   established.
1215</t>
1216<t>
1217   If at any point either one of the peers gets disconnected, any
1218   outstanding data that came from that peer will be passed to the other
1219   one, and after that also the other connection will be terminated by
1220   the proxy. If there is outstanding data to that peer undelivered,
1221   that data will be discarded.
1222</t>
1223
1224</section>
1225</section>
1226</section>
1227
1228
1229<section title="Status Code Definitions" anchor="status.codes">
1230<t>
1231   Each Status-Code is described below, including any metadata required
1232   in the response.
1233</t>
1234
1235<section title="Informational 1xx" anchor="status.1xx">
1236<t>
1237   This class of status code indicates a provisional response,
1238   consisting only of the Status-Line and optional header fields, and is
1239   terminated by an empty line. There are no required header fields for this
1240   class of status code. Since HTTP/1.0 did not define any 1xx status
1241   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1242   except under experimental conditions.
1243</t>
1244<t>
1245   A client &MUST; be prepared to accept one or more 1xx status responses
1246   prior to a regular response, even if the client does not expect a 100
1247   (Continue) status message. Unexpected 1xx status responses &MAY; be
1248   ignored by a user agent.
1249</t>
1250<t>
1251   Proxies &MUST; forward 1xx responses, unless the connection between the
1252   proxy and its client has been closed, or unless the proxy itself
1253   requested the generation of the 1xx response. (For example, if a
1254   proxy adds a "Expect: 100-continue" field when it forwards a request,
1255   then it need not forward the corresponding 100 (Continue)
1256   response(s).)
1257</t>
1258
1259<section title="100 Continue" anchor="status.100">
1260  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1261  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1262<t>
1263   The client &SHOULD; continue with its request. This interim response is
1264   used to inform the client that the initial part of the request has
1265   been received and has not yet been rejected by the server. The client
1266   &SHOULD; continue by sending the remainder of the request or, if the
1267   request has already been completed, ignore this response. The server
1268   &MUST; send a final response after the request has been completed. See
1269   &use100; for detailed discussion of the use and handling of this
1270   status code.
1271</t>
1272</section>
1273
1274<section title="101 Switching Protocols" anchor="status.101">
1275  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1276  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1277<t>
1278   The server understands and is willing to comply with the client's
1279   request, via the Upgrade message header field (&header-upgrade;), for a
1280   change in the application protocol being used on this connection. The
1281   server will switch protocols to those defined by the response's
1282   Upgrade header field immediately after the empty line which
1283   terminates the 101 response.
1284</t>
1285<t>
1286   The protocol &SHOULD; be switched only when it is advantageous to do
1287   so. For example, switching to a newer version of HTTP is advantageous
1288   over older versions, and switching to a real-time, synchronous
1289   protocol might be advantageous when delivering resources that use
1290   such features.
1291</t>
1292</section>
1293</section>
1294
1295<section title="Successful 2xx" anchor="status.2xx">
1296<t>
1297   This class of status code indicates that the client's request was
1298   successfully received, understood, and accepted.
1299</t>
1300
1301<section title="200 OK" anchor="status.200">
1302  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1303  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1304<t>
1305   The request has succeeded. The payload returned with the response
1306   is dependent on the method used in the request, for example:
1307  <list style="hanging">
1308    <t hangText="GET">
1309          a representation of the target resource is sent in the response;
1310    </t>
1311    <t hangText="HEAD">
1312          the same representation as GET, except without the message-body;
1313    </t>
1314    <t hangText="POST">
1315      a representation describing or containing the result of the action;
1316    </t>
1317    <t hangText="TRACE">
1318      a representation containing the request message as received by the
1319      end server.
1320    </t>
1321  </list>
1322</t>
1323<t>
1324   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1325   freshness for 200 responses.
1326</t>
1327</section>
1328
1329<section title="201 Created" anchor="status.201">
1330  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1331  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1332<t>
1333   The request has been fulfilled and has resulted in a new resource being
1334   created. The newly created resource can be referenced by the URI(s)
1335   returned in the payload of the response, with the most specific URI
1336   for the resource given by a Location header field. The response
1337   &SHOULD; include a payload containing a list of resource
1338   characteristics and location(s) from which the user or user agent can
1339   choose the one most appropriate. The payload format is specified by
1340   the media type given in the Content-Type header field. The origin
1341   server &MUST; create the resource before returning the 201 status code.
1342   If the action cannot be carried out immediately, the server &SHOULD;
1343   respond with 202 (Accepted) response instead.
1344</t>
1345<t>
1346   A 201 response &MAY; contain an ETag response header field indicating
1347   the current value of the entity-tag for the representation of the resource
1348   just created (see &header-etag;).
1349</t>
1350</section>
1351
1352<section title="202 Accepted" anchor="status.202">
1353  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1354  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1355<t>
1356   The request has been accepted for processing, but the processing has
1357   not been completed.  The request might or might not eventually be
1358   acted upon, as it might be disallowed when processing actually takes
1359   place. There is no facility for re-sending a status code from an
1360   asynchronous operation such as this.
1361</t>
1362<t>
1363   The 202 response is intentionally non-committal. Its purpose is to
1364   allow a server to accept a request for some other process (perhaps a
1365   batch-oriented process that is only run once per day) without
1366   requiring that the user agent's connection to the server persist
1367   until the process is completed. The representation returned with this
1368   response &SHOULD; include an indication of the request's current status
1369   and either a pointer to a status monitor or some estimate of when the
1370   user can expect the request to be fulfilled.
1371</t>
1372</section>
1373
1374<section title="203 Non-Authoritative Information" anchor="status.203">
1375  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1376  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1377<t>
1378   The returned metadata in the header fields is not the
1379   definitive set as available from the origin server, but is gathered
1380   from a local or a third-party copy. The set presented &MAY; be a subset
1381   or superset of the original version. For example, including local
1382   annotation information about the resource might result in a superset
1383   of the metadata known by the origin server. Use of this
1384   response code is not required and is only appropriate when the
1385   response would otherwise be 200 (OK).
1386</t>
1387<t>
1388   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1389   freshness for 203 responses.
1390</t>
1391
1392</section>
1393
1394<section title="204 No Content" anchor="status.204">
1395  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1396  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1397<t>
1398   The server has successfully fulfilled the request, but there is no
1399   additional content to return in the response payload body.  The
1400   resource metadata and representation metadata in the response message's
1401   header fields refer to the target resource
1402   and its current representation, respectively, after the requested action.
1403   For example, if a 204 status code is received in response to a PUT
1404   and the response contains an ETag header field, then the value of
1405   that field is the current entity-tag for the representation that
1406   was successfully PUT.
1407</t>
1408<t>
1409   If the client is a user agent, it &SHOULD-NOT; change its document view
1410   from that which caused the request to be sent. This response is
1411   primarily intended to allow input for actions to take place without
1412   causing a change to the user agent's active document view, although
1413   any new or updated metadata &SHOULD; be applied to the document
1414   currently in the user agent's active view.
1415</t>
1416<t>
1417   The 204 response &MUST-NOT; include a message-body, and thus is always
1418   terminated by the first empty line after the header fields.
1419</t>
1420</section>
1421
1422<section title="205 Reset Content" anchor="status.205">
1423  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1424  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1425<t>
1426   The server has fulfilled the request and the user agent &SHOULD; reset
1427   the document view which caused the request to be sent. This response
1428   is primarily intended to allow input for actions to take place via
1429   user input, followed by a clearing of the form in which the input is
1430   given so that the user can easily initiate another input action.
1431</t>
1432<t>   
1433   The message-body included with the response &MUST; be empty. Note that
1434   receivers still need to parse the response according to the algorithm defined
1435   in &message-body;.
1436</t>
1437</section>
1438
1439<section title="206 Partial Content" anchor="status.206">
1440  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1441  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1442  <rdf:Description>
1443    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1444  </rdf:Description>
1445<t>
1446   The server has fulfilled the partial GET request for the resource
1447   and the enclosed payload is a partial representation as defined in &status-206;.
1448</t>
1449<t>
1450   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1451   freshness for 206 responses.
1452</t>
1453</section>
1454</section>
1455
1456<section title="Redirection 3xx" anchor="status.3xx">
1457<t>
1458   This class of status code indicates that further action needs to be
1459   taken by the user agent in order to fulfill the request.  The action
1460   required &MAY; be carried out by the user agent without interaction
1461   with the user if and only if the method used in the second request is
1462   known to be "safe", as defined in <xref target="safe.methods"/>.
1463   A client &SHOULD; detect infinite redirection loops, since such loops
1464   generate network traffic for each redirection.
1465</t>
1466<x:note>
1467  <t>
1468    <x:h>Note:</x:h> An earlier version of this specification recommended a
1469    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1470    Content developers need to be aware that some clients might
1471    implement such a fixed limitation.
1472  </t>
1473</x:note>
1474
1475<section title="300 Multiple Choices" anchor="status.300">
1476  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1477  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1478<t>
1479   The target resource has more than one
1480   representation, each with its own specific location, and agent-driven
1481   negotiation information (&content-negotiation;) is being provided so that
1482   the user (or user agent) can select a preferred representation by
1483   redirecting its request to that location.
1484</t>
1485<t>
1486   Unless it was a HEAD request, the response &SHOULD; include a representation
1487   containing a list of representation metadata and location(s) from
1488   which the user or user agent can choose the one most appropriate. The
1489   data format is specified by the media type given in the Content-Type
1490   header field. Depending upon the format and the capabilities of
1491   the user agent, selection of the most appropriate choice &MAY; be
1492   performed automatically. However, this specification does not define
1493   any standard for such automatic selection.
1494</t>
1495<t>
1496   If the server has a preferred choice of representation, it &SHOULD;
1497   include the specific URI for that representation in the Location
1498   field; user agents &MAY; use the Location field value for automatic
1499   redirection.
1500</t>
1501<t>
1502   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1503   freshness for 300 responses.
1504</t>
1505
1506</section>
1507
1508<section title="301 Moved Permanently" anchor="status.301">
1509  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1510  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1511<t>
1512   The target resource has been assigned a new permanent URI and any
1513   future references to this resource &SHOULD; use one of the returned
1514   URIs.  Clients with link editing capabilities ought to automatically
1515   re-link references to the effective request URI to one or more of the new
1516   references returned by the server, where possible.
1517</t>
1518<t>
1519   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1520   freshness for 301 responses.
1521</t>
1522<t>
1523   The new permanent URI &SHOULD; be given by the Location field in the
1524   response. Unless the request method was HEAD, the representation of the
1525   response &SHOULD; contain a short hypertext note with a hyperlink to
1526   the new URI(s).
1527</t>
1528<t>
1529   If the 301 status code is received in response to a request method
1530   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1531   then the request &MAY; be automatically redirected by the user agent without
1532   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1533   request unless it can be confirmed by the user, since this might
1534   change the conditions under which the request was issued.
1535</t>
1536<x:note>
1537  <t>
1538    <x:h>Note:</x:h> When automatically redirecting a POST request after
1539    receiving a 301 status code, some existing HTTP/1.0 user agents
1540    will erroneously change it into a GET request.
1541  </t>
1542</x:note>
1543</section>
1544
1545<section title="302 Found" anchor="status.302">
1546  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1547  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1548<t>
1549   The target resource resides temporarily under a different URI.
1550   Since the redirection might be altered on occasion, the client &SHOULD;
1551   continue to use the effective request URI for future requests.
1552</t>
1553<t>
1554   The temporary URI &SHOULD; be given by the Location field in the
1555   response. Unless the request method was HEAD, the representation of the
1556   response &SHOULD; contain a short hypertext note with a hyperlink to
1557   the new URI(s).
1558</t>
1559<t>
1560   If the 302 status code is received in response to a request method
1561   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1562   then the request &MAY; be automatically redirected by the user agent without
1563   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1564   request unless it can be confirmed by the user, since this might
1565   change the conditions under which the request was issued.
1566</t>
1567<x:note>
1568  <t>
1569    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1570    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1571    specify that the client is not allowed to change the method on the
1572    redirected request.  However, most existing user agent implementations
1573    treat 302 as if it were a 303 response, performing a GET on the Location
1574    field-value regardless of the original request method. Therefore, a
1575    previous version of this specification
1576    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1577    status codes
1578    <xref target="status.303" format="none">303</xref> and
1579    <xref target="status.307" format="none">307</xref> for servers that wish
1580    to make unambiguously clear which kind of reaction is expected of the
1581    client.
1582  </t>
1583</x:note>
1584</section>
1585
1586<section title="303 See Other" anchor="status.303">
1587  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1588  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1589<t>
1590   The server directs the user agent to a different resource, indicated
1591   by a URI in the Location header field, that provides an indirect
1592   response to the original request.  The user agent &MAY; perform a GET
1593   request on the URI in the Location field in order to obtain a
1594   representation corresponding to the response, be redirected again,
1595   or end with an error status.  The Location URI is not a substitute
1596   reference for the effective request URI.
1597</t>
1598<t>
1599   The 303 status code is generally applicable to any HTTP method.  It is
1600   primarily used to allow the output of a POST action to redirect
1601   the user agent to a selected resource, since doing so provides the
1602   information corresponding to the POST response in a form that
1603   can be separately identified, bookmarked, and cached independent
1604   of the original request.
1605</t>
1606<t>
1607   A 303 response to a GET request indicates that the requested
1608   resource does not have a representation of its own that can be
1609   transferred by the server over HTTP.  The Location URI indicates a
1610   resource that is descriptive of the target resource, such that the
1611   follow-on representation might be useful to recipients without
1612   implying that it adequately represents the target resource.
1613   Note that answers to the questions of what can be represented, what
1614   representations are adequate, and what might be a useful description
1615   are outside the scope of HTTP and thus entirely determined by the
1616   URI owner(s).
1617</t>
1618<t>
1619   Except for responses to a HEAD request, the representation of a 303
1620   response &SHOULD; contain a short hypertext note with a hyperlink
1621   to the Location URI.
1622</t>
1623</section>
1624
1625<section title="304 Not Modified" anchor="status.304">
1626  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1627  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1628  <rdf:Description>
1629    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1630  </rdf:Description>
1631<t>
1632   The response to the request has not been modified since the conditions
1633   indicated by the client's conditional GET request, as defined in &status-304;.
1634</t>
1635</section>
1636
1637<section title="305 Use Proxy" anchor="status.305">
1638  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1639  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1640<t>
1641   The 305 status code was defined in a previous version of this specification
1642   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1643</t>
1644</section>
1645
1646<section title="306 (Unused)" anchor="status.306">
1647  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1648  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1649<t>
1650   The 306 status code was used in a previous version of the
1651   specification, is no longer used, and the code is reserved.
1652</t>
1653</section>
1654
1655<section title="307 Temporary Redirect" anchor="status.307">
1656  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1657  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1658<t>
1659   The target resource resides temporarily under a different URI.
1660   Since the redirection can change over time, the client &SHOULD;
1661   continue to use the effective request URI for future requests.
1662</t>
1663<t>
1664   The temporary URI &SHOULD; be given by the Location field in the
1665   response. Unless the request method was HEAD, the representation of the
1666   response &SHOULD; contain a short hypertext note with a hyperlink to
1667   the new URI(s), since many pre-HTTP/1.1 user agents do not
1668   understand the 307 status code. Therefore, the note &SHOULD; contain the
1669   information necessary for a user to repeat the original request on
1670   the new URI.
1671</t>
1672<t>
1673   If the 307 status code is received in response to a request method
1674   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1675   then the request &MAY; be automatically redirected by the user agent without
1676   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1677   request unless it can be confirmed by the user, since this might
1678   change the conditions under which the request was issued.
1679</t>
1680</section>
1681</section>
1682
1683<section title="Client Error 4xx" anchor="status.4xx">
1684<t>
1685   The 4xx class of status code is intended for cases in which the
1686   client seems to have erred. Except when responding to a HEAD request,
1687   the server &SHOULD; include a representation containing an explanation of the
1688   error situation, and whether it is a temporary or permanent
1689   condition. These status codes are applicable to any request method.
1690   User agents &SHOULD; display any included representation to the user.
1691</t>
1692<t>
1693   If the client is sending data, a server implementation using TCP
1694   &SHOULD; be careful to ensure that the client acknowledges receipt of
1695   the packet(s) containing the response, before the server closes the
1696   input connection. If the client continues sending data to the server
1697   after the close, the server's TCP stack will send a reset packet to
1698   the client, which might erase the client's unacknowledged input buffers
1699   before they can be read and interpreted by the HTTP application.
1700</t>
1701
1702<section title="400 Bad Request" anchor="status.400">
1703  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1704  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1705<t>
1706   The request could not be understood by the server due to malformed
1707   syntax. The client &SHOULD-NOT; repeat the request without
1708   modifications.
1709</t>
1710</section>
1711
1712<section title="401 Unauthorized" anchor="status.401">
1713  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1714  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1715  <rdf:Description>
1716    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part7</redirects-to>
1717  </rdf:Description>
1718<t>
1719   The request requires user authentication (see &status-401;).
1720</t>
1721</section>
1722
1723<section title="402 Payment Required" anchor="status.402">
1724  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1725  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1726<t>
1727   This code is reserved for future use.
1728</t>
1729</section>
1730
1731<section title="403 Forbidden" anchor="status.403">
1732  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1733  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1734<t>
1735   The server understood the request, but is refusing to fulfill it.
1736   Authorization will not help and the request &SHOULD-NOT;  be repeated.
1737   If the request method was not HEAD and the server wishes to make
1738   public why the request has not been fulfilled, it &SHOULD; describe the
1739   reason for the refusal in the representation.  If the server does not wish to
1740   make this information available to the client, the status code 404
1741   (Not Found) can be used instead.
1742</t>
1743</section>
1744
1745<section title="404 Not Found" anchor="status.404">
1746  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1747  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1748<t>
1749   The server has not found anything matching the effective request URI. No
1750   indication is given of whether the condition is temporary or
1751   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1752   knows, through some internally configurable mechanism, that an old
1753   resource is permanently unavailable and has no forwarding address.
1754   This status code is commonly used when the server does not wish to
1755   reveal exactly why the request has been refused, or when no other
1756   response is applicable.
1757</t>
1758</section>
1759
1760<section title="405 Method Not Allowed" anchor="status.405">
1761  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1762  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1763<t>
1764   The method specified in the Request-Line is not allowed for the target
1765   resource. The response &MUST; include an
1766   Allow header field containing a list of valid methods for the requested
1767   resource.
1768</t>
1769</section>
1770
1771<section title="406 Not Acceptable" anchor="status.406">
1772  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1773  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1774<t>
1775   The resource identified by the request is only capable of generating
1776   response representations which have content characteristics not acceptable
1777   according to the accept header fields sent in the request.
1778</t>
1779<t>
1780   Unless it was a HEAD request, the response &SHOULD; include a representation
1781   containing a list of available representation characteristics and location(s)
1782   from which the user or user agent can choose the one most
1783   appropriate. The data format is specified by the media type given
1784   in the Content-Type header field. Depending upon the format and the
1785   capabilities of the user agent, selection of the most appropriate
1786   choice &MAY; be performed automatically. However, this specification
1787   does not define any standard for such automatic selection.
1788</t>
1789<x:note>
1790  <t>
1791    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1792    not acceptable according to the accept header fields sent in the
1793    request. In some cases, this might even be preferable to sending a
1794    406 response. User agents are encouraged to inspect the header fields of
1795    an incoming response to determine if it is acceptable.
1796  </t>
1797</x:note>
1798<t>
1799   If the response could be unacceptable, a user agent &SHOULD;
1800   temporarily stop receipt of more data and query the user for a
1801   decision on further actions.
1802</t>
1803</section>
1804
1805<section title="407 Proxy Authentication Required" anchor="status.407">
1806  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1807  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1808<t>
1809   This code is similar to 401 (Unauthorized), but indicates that the
1810   client must first authenticate itself with the proxy (see &status-407;).
1811</t>
1812</section>
1813
1814<section title="408 Request Timeout" anchor="status.408">
1815  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1816  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1817<t>
1818   The client did not produce a request within the time that the server
1819   was prepared to wait. The client &MAY; repeat the request without
1820   modifications at any later time.
1821</t>
1822</section>
1823
1824<section title="409 Conflict" anchor="status.409">
1825  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1826  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1827<t>
1828   The request could not be completed due to a conflict with the current
1829   state of the resource. This code is only allowed in situations where
1830   it is expected that the user might be able to resolve the conflict
1831   and resubmit the request. The response body &SHOULD; include enough
1832   information for the user to recognize the source of the conflict.
1833   Ideally, the response representation would include enough information for the
1834   user or user agent to fix the problem; however, that might not be
1835   possible and is not required.
1836</t>
1837<t>
1838   Conflicts are most likely to occur in response to a PUT request. For
1839   example, if versioning were being used and the representation being PUT
1840   included changes to a resource which conflict with those made by an
1841   earlier (third-party) request, the server might use the 409 response
1842   to indicate that it can't complete the request. In this case, the
1843   response representation would likely contain a list of the differences
1844   between the two versions in a format defined by the response
1845   Content-Type.
1846</t>
1847</section>
1848
1849<section title="410 Gone" anchor="status.410">
1850  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1851  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1852<t>
1853   The target resource is no longer available at the server and no
1854   forwarding address is known. This condition is expected to be
1855   considered permanent. Clients with link editing capabilities &SHOULD;
1856   delete references to the effective request URI after user approval. If the
1857   server does not know, or has no facility to determine, whether or not
1858   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1859   used instead.
1860</t>
1861<t>
1862   The 410 response is primarily intended to assist the task of web
1863   maintenance by notifying the recipient that the resource is
1864   intentionally unavailable and that the server owners desire that
1865   remote links to that resource be removed. Such an event is common for
1866   limited-time, promotional services and for resources belonging to
1867   individuals no longer working at the server's site. It is not
1868   necessary to mark all permanently unavailable resources as "gone" or
1869   to keep the mark for any length of time &mdash; that is left to the
1870   discretion of the server owner.
1871</t>
1872<t>
1873   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine freshness
1874   for 410 responses.
1875</t>
1876
1877</section>
1878
1879<section title="411 Length Required" anchor="status.411">
1880  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1881  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1882<t>
1883   The server refuses to accept the request without a defined Content-Length.
1884   The client &MAY; repeat the request if it adds a valid
1885   Content-Length header field containing the length of the message-body
1886   in the request message.
1887</t>
1888</section>
1889
1890<section title="412 Precondition Failed" anchor="status.412">
1891  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1892  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1893  <rdf:Description>
1894    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1895  </rdf:Description>
1896<t>
1897   The precondition given in one or more of the header fields
1898   evaluated to false when it was tested on the server, as defined in
1899   &status-412;.
1900</t>
1901</section>
1902
1903<section title="413 Request Entity Too Large" anchor="status.413">
1904  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1905  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1906<t>
1907   The server is refusing to process a request because the request
1908   representation is larger than the server is willing or able to process. The
1909   server &MAY; close the connection to prevent the client from continuing
1910   the request.
1911</t>
1912<t>
1913   If the condition is temporary, the server &SHOULD; include a Retry-After
1914   header field to indicate that it is temporary and after what
1915   time the client &MAY; try again.
1916</t>
1917</section>
1918
1919<section title="414 URI Too Long" anchor="status.414">
1920  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1921  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1922<t>
1923   The server is refusing to service the request because the effective request URI
1924   is longer than the server is willing to interpret. This rare
1925   condition is only likely to occur when a client has improperly
1926   converted a POST request to a GET request with long query
1927   information, when the client has descended into a URI "black hole" of
1928   redirection (e.g., a redirected URI prefix that points to a suffix of
1929   itself), or when the server is under attack by a client attempting to
1930   exploit security holes present in some servers using fixed-length
1931   buffers for reading or manipulating the effective request URI.
1932</t>
1933</section>
1934
1935<section title="415 Unsupported Media Type" anchor="status.415">
1936  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1937  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1938<t>
1939   The server is refusing to service the request because the request
1940   payload is in a format not supported by this request method on the
1941   target resource.
1942</t>
1943</section>
1944
1945<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1946  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1947  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1948  <rdf:Description>
1949    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1950  </rdf:Description>
1951<t>
1952   The request included a Range header field (&header-range;) and none of
1953   the range-specifier values in this field overlap the current extent
1954   of the selected resource. See &status-416;.
1955</t>
1956</section>
1957
1958<section title="417 Expectation Failed" anchor="status.417">
1959  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
1960  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
1961<t>
1962   The expectation given in an Expect header field (see <xref target="header.expect"/>)
1963   could not be met by this server, or, if the server is a proxy,
1964   the server has unambiguous evidence that the request could not be met
1965   by the next-hop server.
1966</t>
1967</section>
1968
1969<section title="426 Upgrade Required" anchor="status.426">
1970  <iref primary="true" item="426 Upgrade Required (status code)" x:for-anchor=""/>
1971  <iref primary="true" item="Status Codes" subitem="426 Upgrade Required" x:for-anchor=""/>
1972<t>
1973   The request can not be completed without a prior protocol upgrade. This
1974   response &MUST; include an Upgrade header field (&header-upgrade;)
1975   specifying the required protocols.
1976</t>
1977<figure>
1978<preamble>Example:</preamble>
1979<artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1980HTTP/1.1 426 Upgrade Required
1981Upgrade: HTTP/2.0
1982Connection: Upgrade
1983
1984</artwork></figure>
1985<t>
1986   The server &SHOULD; include a message body in the 426 response which
1987   indicates in human readable form the reason for the error and describes any
1988   alternative courses which may be available to the user.
1989</t>
1990</section>
1991</section>
1992
1993<section title="Server Error 5xx" anchor="status.5xx">
1994<t>
1995   Response status codes beginning with the digit "5" indicate cases in
1996   which the server is aware that it has erred or is incapable of
1997   performing the request. Except when responding to a HEAD request, the
1998   server &SHOULD; include a representation containing an explanation of the
1999   error situation, and whether it is a temporary or permanent
2000   condition. User agents &SHOULD; display any included representation to the
2001   user. These response codes are applicable to any request method.
2002</t>
2003
2004<section title="500 Internal Server Error" anchor="status.500">
2005  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
2006  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
2007<t>
2008   The server encountered an unexpected condition which prevented it
2009   from fulfilling the request.
2010</t>
2011</section>
2012
2013<section title="501 Not Implemented" anchor="status.501">
2014  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
2015  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
2016<t>
2017   The server does not support the functionality required to fulfill the
2018   request. This is the appropriate response when the server does not
2019   recognize the request method and is not capable of supporting it for
2020   any resource.
2021</t>
2022</section>
2023
2024<section title="502 Bad Gateway" anchor="status.502">
2025  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
2026  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
2027<t>
2028   The server, while acting as a gateway or proxy, received an invalid
2029   response from the upstream server it accessed in attempting to
2030   fulfill the request.
2031</t>
2032</section>
2033
2034<section title="503 Service Unavailable" anchor="status.503">
2035  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
2036  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
2037<t>
2038   The server is currently unable to handle the request due to a
2039   temporary overloading or maintenance of the server. The implication
2040   is that this is a temporary condition which will be alleviated after
2041   some delay. If known, the length of the delay &MAY; be indicated in a
2042   Retry-After header field. If no Retry-After is given, the client &SHOULD;
2043   handle the response as it would for a 500 response.
2044</t>
2045<x:note>
2046  <t>
2047    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
2048    server must use it when becoming overloaded. Some servers might wish
2049    to simply refuse the connection.
2050  </t>
2051</x:note>
2052</section>
2053
2054<section title="504 Gateway Timeout" anchor="status.504">
2055  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
2056  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
2057<t>
2058   The server, while acting as a gateway or proxy, did not receive a
2059   timely response from the upstream server specified by the URI (e.g.,
2060   HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
2061   to access in attempting to complete the request.
2062</t>
2063<x:note>
2064  <t>
2065    <x:h>Note</x:h> to implementors: some deployed proxies are known to
2066    return 400 or 500 when DNS lookups time out.
2067  </t>
2068</x:note>
2069</section>
2070
2071<section title="505 HTTP Version Not Supported" anchor="status.505">
2072  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
2073  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
2074<t>
2075   The server does not support, or refuses to support, the protocol
2076   version that was used in the request message. The server is
2077   indicating that it is unable or unwilling to complete the request
2078   using the same major version as the client, as described in &http-version;,
2079   other than with this error message. The response &SHOULD; contain
2080   a representation describing why that version is not supported and what other
2081   protocols are supported by that server.
2082</t>
2083
2084</section>
2085</section>
2086</section>
2087
2088
2089<section title="Header Field Definitions" anchor="header.fields">
2090<t>
2091   This section defines the syntax and semantics of HTTP/1.1 header fields
2092   related to request and response semantics.
2093</t>
2094
2095<section title="Allow" anchor="header.allow">
2096  <iref primary="true" item="Allow header field" x:for-anchor=""/>
2097  <iref primary="true" item="Header Fields" subitem="Allow" x:for-anchor=""/>
2098  <x:anchor-alias value="Allow"/>
2099  <x:anchor-alias value="Allow-v"/>
2100<t>
2101   The "Allow" header field lists the set of methods advertised as
2102   supported by the target resource. The purpose of this field is strictly to
2103   inform the recipient of valid request methods associated with the resource.
2104</t>
2105<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/><iref primary="true" item="Grammar" subitem="Allow-v"/>
2106  <x:ref>Allow</x:ref>   = "Allow" ":" <x:ref>OWS</x:ref> <x:ref>Allow-v</x:ref>
2107  <x:ref>Allow-v</x:ref> = #<x:ref>Method</x:ref>
2108</artwork></figure>
2109<t>
2110   Example of use:
2111</t>
2112<figure><artwork type="example">
2113  Allow: GET, HEAD, PUT
2114</artwork></figure>
2115<t>
2116   The actual set of allowed methods is defined by the origin server at the
2117   time of each request.
2118</t>
2119<t>
2120   A proxy &MUST-NOT; modify the Allow header field &mdash; it does not need to
2121   understand all the methods specified in order to handle them according to
2122   the generic message handling rules.
2123</t>
2124</section>
2125
2126<section title="Expect" anchor="header.expect">
2127  <iref primary="true" item="Expect header field" x:for-anchor=""/>
2128  <iref primary="true" item="Header Fields" subitem="Expect" x:for-anchor=""/>
2129  <x:anchor-alias value="Expect"/>
2130  <x:anchor-alias value="Expect-v"/>
2131  <x:anchor-alias value="expectation"/>
2132  <x:anchor-alias value="expectation-extension"/>
2133  <x:anchor-alias value="expect-params"/>
2134<t>
2135   The "Expect" header field is used to indicate that particular
2136   server behaviors are required by the client.
2137</t>
2138<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Expect"/><iref primary="true" item="Grammar" subitem="Expect-v"/><iref primary="true" item="Grammar" subitem="expectation"/><iref primary="true" item="Grammar" subitem="expectation-extension"/><iref primary="true" item="Grammar" subitem="expect-params"/>
2139  <x:ref>Expect</x:ref>       = "Expect" ":" <x:ref>OWS</x:ref> <x:ref>Expect-v</x:ref>
2140  <x:ref>Expect-v</x:ref>     = 1#<x:ref>expectation</x:ref>
2141 
2142  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
2143  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
2144                           *<x:ref>expect-params</x:ref> ]
2145  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
2146</artwork></figure>
2147<t>
2148   A server that does not understand or is unable to comply with any of
2149   the expectation values in the Expect field of a request &MUST; respond
2150   with appropriate error status code. The server &MUST; respond with a 417
2151   (Expectation Failed) status code if any of the expectations cannot be met
2152   or, if there are other problems with the request, some other 4xx
2153   status code.
2154</t>
2155<t>
2156   This header field is defined with extensible syntax to allow for
2157   future extensions. If a server receives a request containing an
2158   Expect field that includes an expectation-extension that it does not
2159   support, it &MUST; respond with a 417 (Expectation Failed) status code.
2160</t>
2161<t>
2162   Comparison of expectation values is case-insensitive for unquoted
2163   tokens (including the 100-continue token), and is case-sensitive for
2164   quoted-string expectation-extensions.
2165</t>
2166<t>
2167   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
2168   return a 417 (Expectation Failed) status code if it receives a request
2169   with an expectation that it cannot meet. However, the Expect
2170   header field itself is end-to-end; it &MUST; be forwarded if the
2171   request is forwarded.
2172</t>
2173<t>
2174   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
2175   Expect header field.
2176</t>
2177<t>
2178   See &use100; for the use of the 100 (Continue) status code.
2179</t>
2180</section>
2181
2182<section title="From" anchor="header.from">
2183  <iref primary="true" item="From header field" x:for-anchor=""/>
2184  <iref primary="true" item="Header Fields" subitem="From" x:for-anchor=""/>
2185  <x:anchor-alias value="From"/>
2186  <x:anchor-alias value="From-v"/>
2187  <x:anchor-alias value="mailbox"/>
2188<t>
2189   The "From" header field, if given, &SHOULD; contain an Internet
2190   e-mail address for the human user who controls the requesting user
2191   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
2192   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
2193</t>
2194<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/><iref primary="true" item="Grammar" subitem="From-v"/>
2195  <x:ref>From</x:ref>    = "From" ":" <x:ref>OWS</x:ref> <x:ref>From-v</x:ref>
2196  <x:ref>From-v</x:ref>  = <x:ref>mailbox</x:ref>
2197 
2198  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
2199</artwork></figure>
2200<t>
2201   An example is:
2202</t>
2203<figure><artwork type="example">
2204  From: webmaster@example.org
2205</artwork></figure>
2206<t>
2207   This header field &MAY; be used for logging purposes and as a means for
2208   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
2209   be used as an insecure form of access protection. The interpretation
2210   of this field is that the request is being performed on behalf of the
2211   person given, who accepts responsibility for the method performed. In
2212   particular, robot agents &SHOULD; include this header field so that the
2213   person responsible for running the robot can be contacted if problems
2214   occur on the receiving end.
2215</t>
2216<t>
2217   The Internet e-mail address in this field &MAY; be separate from the
2218   Internet host which issued the request. For example, when a request
2219   is passed through a proxy the original issuer's address &SHOULD; be
2220   used.
2221</t>
2222<t>
2223   The client &SHOULD-NOT;  send the From header field without the user's
2224   approval, as it might conflict with the user's privacy interests or
2225   their site's security policy. It is strongly recommended that the
2226   user be able to disable, enable, and modify the value of this field
2227   at any time prior to a request.
2228</t>
2229</section>
2230
2231<section title="Location" anchor="header.location">
2232  <iref primary="true" item="Location header field" x:for-anchor=""/>
2233  <iref primary="true" item="Header Fields" subitem="Location" x:for-anchor=""/>
2234  <x:anchor-alias value="Location"/>
2235  <x:anchor-alias value="Location-v"/>
2236<t>
2237   The "Location" header field is used to identify a newly created
2238   resource, or to redirect the recipient to a different location for
2239   completion of the request.
2240</t>
2241<t>
2242   For 201 (Created) responses, the Location is the URI of the new resource
2243   which was created by the request. For 3xx responses, the location &SHOULD;
2244   indicate the server's preferred URI for automatic redirection to the
2245   resource.
2246</t>
2247<t>
2248   The field value consists of a single URI-reference. When it has the form
2249   of a relative reference (<xref target="RFC3986" x:fmt="," x:sec="4.2"/>),
2250   the final value is computed by resolving it against the effective request
2251   URI (<xref target="RFC3986" x:fmt="," x:sec="5"/>).
2252</t>
2253<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/><iref primary="true" item="Grammar" subitem="Location-v"/>
2254  <x:ref>Location</x:ref>       = "Location" ":" <x:ref>OWS</x:ref> <x:ref>Location-v</x:ref>
2255  <x:ref>Location-v</x:ref>     = <x:ref>URI-reference</x:ref>
2256</artwork></figure>
2257<figure>
2258<preamble>Examples are:</preamble><!--DO NOT DARE changing the vertical WSP below, it's necessary this way for xml2rfc-->
2259<artwork type="example">
2260  Location: http://www.example.org/pub/WWW/People.html#tim
2261</artwork></figure><figure><artwork type="example">  Location: /index.html
2262</artwork></figure>
2263<t>
2264   There are circumstances in which a fragment identifier in a Location URI
2265   would not be appropriate:
2266   <list style="symbols">
2267      <t>With a 201 Created response, because in this usage the Location header
2268      field specifies the URI for the entire created resource.</t>
2269      <t>With 305 Use Proxy.</t>
2270   </list>
2271</t>
2272<x:note>
2273  <t>
2274    <x:h>Note:</x:h> This specification does not define precedence rules
2275    for the case where the original URI, as navigated to by the user
2276    agent, and the Location header field value both contain fragment
2277    identifiers. Thus be aware that including fragment identifiers might
2278    inconvenience anyone relying on the semantics of the original URI's
2279    fragment identifier.
2280  </t>
2281</x:note>
2282<x:note>
2283  <t>
2284    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2285    from Location in that the Content-Location identifies the most specific
2286    resource corresponding to the enclosed representation.
2287    It is therefore possible for a response to contain header fields for
2288    both Location and Content-Location.
2289  </t>
2290</x:note>
2291</section>
2292
2293<section title="Max-Forwards" anchor="header.max-forwards">
2294  <iref primary="true" item="Max-Forwards header field" x:for-anchor=""/>
2295  <iref primary="true" item="Header Fields" subitem="Max-Forwards" x:for-anchor=""/>
2296  <x:anchor-alias value="Max-Forwards"/>
2297  <x:anchor-alias value="Max-Forwards-v"/>
2298<t>
2299   The "Max-Forwards" header field provides a mechanism with the
2300   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>)
2301   methods to limit the number of times that the request is forwarded by
2302   proxies or gateways. This can be useful when the client is attempting to
2303   trace a request which appears to be failing or looping in mid-chain.
2304</t>
2305<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/><iref primary="true" item="Grammar" subitem="Max-Forwards-v"/>
2306  <x:ref>Max-Forwards</x:ref>   = "Max-Forwards" ":" <x:ref>OWS</x:ref> <x:ref>Max-Forwards-v</x:ref>
2307  <x:ref>Max-Forwards-v</x:ref> = 1*<x:ref>DIGIT</x:ref>
2308</artwork></figure>
2309<t>
2310   The Max-Forwards value is a decimal integer indicating the remaining
2311   number of times this request message can be forwarded.
2312</t>
2313<t>
2314   Each proxy or gateway recipient of a TRACE or OPTIONS request
2315   containing a Max-Forwards header field &MUST; check and update its
2316   value prior to forwarding the request. If the received value is zero
2317   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2318   respond as the final recipient. If the received Max-Forwards value is
2319   greater than zero, then the forwarded message &MUST; contain an updated
2320   Max-Forwards field with a value decremented by one (1).
2321</t>
2322<t>
2323   The Max-Forwards header field &MAY; be ignored for all other request
2324   methods.
2325</t>
2326</section>
2327
2328<section title="Referer" anchor="header.referer">
2329  <iref primary="true" item="Referer header field" x:for-anchor=""/>
2330  <iref primary="true" item="Header Fields" subitem="Referer" x:for-anchor=""/>
2331  <x:anchor-alias value="Referer"/>
2332  <x:anchor-alias value="Referer-v"/>
2333<t>
2334   The "Referer" [sic] header field allows the client to specify the
2335   URI of the resource from which the effective request URI was obtained (the
2336   "referrer", although the header field is misspelled.).
2337</t>
2338<t>
2339   The Referer header field allows servers to generate lists of back-links to
2340   resources for interest, logging, optimized caching, etc. It also allows
2341   obsolete or mistyped links to be traced for maintenance. Some servers use
2342   Referer as a means of controlling where they allow links from (so-called
2343   "deep linking"), but legitimate requests do not always
2344   contain a Referer header field.
2345</t>
2346<t>
2347   If the effective request URI was obtained from a source that does not have its own
2348   URI (e.g., input from the user keyboard), the Referer field &MUST; either be
2349   sent with the value "about:blank", or not be sent at all. Note that this
2350   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2351</t>
2352<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/><iref primary="true" item="Grammar" subitem="Referer-v"/>
2353  <x:ref>Referer</x:ref>        = "Referer" ":" <x:ref>OWS</x:ref> <x:ref>Referer-v</x:ref>
2354  <x:ref>Referer-v</x:ref>      = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2355</artwork></figure>
2356<t>
2357   Example:
2358</t>
2359<figure><artwork type="example">
2360  Referer: http://www.example.org/hypertext/Overview.html
2361</artwork></figure>
2362<t>
2363   If the field value is a relative URI, it &SHOULD; be interpreted
2364   relative to the effective request URI. The URI &MUST-NOT; include a fragment. See
2365   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2366</t>
2367</section>
2368
2369<section title="Retry-After" anchor="header.retry-after">
2370  <iref primary="true" item="Retry-After header field" x:for-anchor=""/>
2371  <iref primary="true" item="Header Fields" subitem="Retry-After" x:for-anchor=""/>
2372  <x:anchor-alias value="Retry-After"/>
2373  <x:anchor-alias value="Retry-After-v"/>
2374<t>
2375   The header "Retry-After" field can be used with a 503 (Service
2376   Unavailable) response to indicate how long the service is expected to
2377   be unavailable to the requesting client. This field &MAY; also be used
2378   with any 3xx (Redirection) response to indicate the minimum time the
2379   user-agent is asked wait before issuing the redirected request.
2380</t>
2381<t>
2382   The value of this field can be either an HTTP-date or an integer number
2383   of seconds (in decimal) after the time of the response.
2384</t>
2385<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/><iref primary="true" item="Grammar" subitem="Retry-After-v"/>
2386  <x:ref>Retry-After</x:ref>   = "Retry-After" ":" <x:ref>OWS</x:ref> <x:ref>Retry-After-v</x:ref>
2387  <x:ref>Retry-After-v</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2388</artwork></figure>
2389<t anchor="rule.delta-seconds">
2390  <x:anchor-alias value="delta-seconds"/>
2391   Time spans are non-negative decimal integers, representing time in
2392   seconds.
2393</t>
2394<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2395  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2396</artwork></figure>
2397<t>
2398   Two examples of its use are
2399</t>
2400<figure><artwork type="example">
2401  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2402  Retry-After: 120
2403</artwork></figure>
2404<t>
2405   In the latter example, the delay is 2 minutes.
2406</t>
2407</section>
2408
2409<section title="Server" anchor="header.server">
2410  <iref primary="true" item="Server header field" x:for-anchor=""/>
2411  <iref primary="true" item="Header Fields" subitem="Server" x:for-anchor=""/>
2412  <x:anchor-alias value="Server"/>
2413  <x:anchor-alias value="Server-v"/>
2414<t>
2415   The "Server" header field contains information about the
2416   software used by the origin server to handle the request.
2417</t>
2418<t>
2419   The field can contain multiple product tokens (&product-tokens;) and
2420   comments (&header-fields;) identifying the server and any significant
2421   subproducts. The product tokens are listed in order of their significance
2422   for identifying the application.
2423</t>
2424<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/><iref primary="true" item="Grammar" subitem="Server-v"/>
2425  <x:ref>Server</x:ref>         = "Server" ":" <x:ref>OWS</x:ref> <x:ref>Server-v</x:ref>
2426  <x:ref>Server-v</x:ref>       = <x:ref>product</x:ref>
2427                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2428</artwork></figure>
2429<t>
2430   Example:
2431</t>
2432<figure><artwork type="example">
2433  Server: CERN/3.0 libwww/2.17
2434</artwork></figure>
2435<t>
2436   If the response is being forwarded through a proxy, the proxy
2437   application &MUST-NOT; modify the Server header field. Instead, it
2438   &MUST; include a Via field (as described in &header-via;).
2439</t>
2440<x:note>
2441  <t>
2442    <x:h>Note:</x:h> Revealing the specific software version of the server might
2443    allow the server machine to become more vulnerable to attacks
2444    against software that is known to contain security holes. Server
2445    implementors are encouraged to make this field a configurable
2446    option.
2447  </t>
2448</x:note>
2449</section>
2450
2451<section title="User-Agent" anchor="header.user-agent">
2452  <iref primary="true" item="User-Agent header field" x:for-anchor=""/>
2453  <iref primary="true" item="Header Fields" subitem="User-Agent" x:for-anchor=""/>
2454  <x:anchor-alias value="User-Agent"/>
2455  <x:anchor-alias value="User-Agent-v"/>
2456<t>
2457   The "User-Agent" header field contains information about the user
2458   agent originating the request. User agents &SHOULD; include this field with
2459   requests.
2460</t>
2461<t>
2462   Typically, it is used for statistical purposes, the tracing of protocol
2463   violations, and tailoring responses to avoid particular user agent
2464   limitations.
2465</t>
2466<t>
2467   The field can contain multiple product tokens (&product-tokens;)
2468   and comments (&header-fields;) identifying the agent and its
2469   significant subproducts. By convention, the product tokens are listed in
2470   order of their significance for identifying the application.
2471</t>
2472<t>
2473   Because this field is usually sent on every request a user agent makes,
2474   implementations are encouraged not to include needlessly fine-grained
2475   detail, and to limit (or even prohibit) the addition of subproducts by third
2476   parties. Overly long and detailed User-Agent field values make requests
2477   larger and can also be used to identify ("fingerprint") the user against
2478   their wishes.
2479</t>
2480<t>
2481   Likewise, implementations are encouraged not to use the product tokens of
2482   other implementations in order to declare compatibility with them, as this
2483   circumvents the purpose of the field. Finally, they are encouraged not to
2484   use comments to identify products; doing so makes the field value more
2485   difficult to parse.
2486</t>
2487<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/><iref primary="true" item="Grammar" subitem="User-Agent-v"/>
2488  <x:ref>User-Agent</x:ref>     = "User-Agent" ":" <x:ref>OWS</x:ref> <x:ref>User-Agent-v</x:ref>
2489  <x:ref>User-Agent-v</x:ref>   = <x:ref>product</x:ref> *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2490</artwork></figure>
2491<t>
2492   Example:
2493</t>
2494<figure><artwork type="example">
2495  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2496</artwork></figure>
2497</section>
2498
2499</section>
2500
2501<section title="IANA Considerations" anchor="IANA.considerations">
2502
2503<section title="Method Registry" anchor="method.registration">
2504<t>
2505  The registration procedure for HTTP request methods is defined by
2506  <xref target="method.registry"/> of this document.
2507</t>
2508<t>
2509   The HTTP Method Registry shall be created at <eref target="http://www.iana.org/assignments/http-methods"/>
2510   and be populated with the registrations below:
2511</t>
2512<?BEGININC p2-semantics.iana-methods ?>
2513<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2514<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2515   <ttcol>Method</ttcol>
2516   <ttcol>Safe</ttcol>
2517   <ttcol>Reference</ttcol>
2518   <c>CONNECT</c>
2519   <c>no</c>
2520   <c>
2521      <xref target="CONNECT"/>
2522   </c>
2523   <c>DELETE</c>
2524   <c>no</c>
2525   <c>
2526      <xref target="DELETE"/>
2527   </c>
2528   <c>GET</c>
2529   <c>yes</c>
2530   <c>
2531      <xref target="GET"/>
2532   </c>
2533   <c>HEAD</c>
2534   <c>yes</c>
2535   <c>
2536      <xref target="HEAD"/>
2537   </c>
2538   <c>OPTIONS</c>
2539   <c>yes</c>
2540   <c>
2541      <xref target="OPTIONS"/>
2542   </c>
2543   <c>POST</c>
2544   <c>no</c>
2545   <c>
2546      <xref target="POST"/>
2547   </c>
2548   <c>PUT</c>
2549   <c>no</c>
2550   <c>
2551      <xref target="PUT"/>
2552   </c>
2553   <c>TRACE</c>
2554   <c>yes</c>
2555   <c>
2556      <xref target="TRACE"/>
2557   </c>
2558</texttable>
2559<!--(END)-->
2560<?ENDINC p2-semantics.iana-methods ?>
2561</section>
2562
2563<section title="Status Code Registry" anchor="status.code.registration">
2564<t>
2565   The registration procedure for HTTP Status Codes &mdash; previously defined
2566   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> &mdash; is now defined
2567   by <xref target="status.code.registry"/> of this document.
2568</t>
2569<t>
2570   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2571   shall be updated with the registrations below:
2572</t>
2573<?BEGININC p2-semantics.iana-status-codes ?>
2574<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2575<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2576   <ttcol>Value</ttcol>
2577   <ttcol>Description</ttcol>
2578   <ttcol>Reference</ttcol>
2579   <c>100</c>
2580   <c>Continue</c>
2581   <c>
2582      <xref target="status.100"/>
2583   </c>
2584   <c>101</c>
2585   <c>Switching Protocols</c>
2586   <c>
2587      <xref target="status.101"/>
2588   </c>
2589   <c>200</c>
2590   <c>OK</c>
2591   <c>
2592      <xref target="status.200"/>
2593   </c>
2594   <c>201</c>
2595   <c>Created</c>
2596   <c>
2597      <xref target="status.201"/>
2598   </c>
2599   <c>202</c>
2600   <c>Accepted</c>
2601   <c>
2602      <xref target="status.202"/>
2603   </c>
2604   <c>203</c>
2605   <c>Non-Authoritative Information</c>
2606   <c>
2607      <xref target="status.203"/>
2608   </c>
2609   <c>204</c>
2610   <c>No Content</c>
2611   <c>
2612      <xref target="status.204"/>
2613   </c>
2614   <c>205</c>
2615   <c>Reset Content</c>
2616   <c>
2617      <xref target="status.205"/>
2618   </c>
2619   <c>300</c>
2620   <c>Multiple Choices</c>
2621   <c>
2622      <xref target="status.300"/>
2623   </c>
2624   <c>301</c>
2625   <c>Moved Permanently</c>
2626   <c>
2627      <xref target="status.301"/>
2628   </c>
2629   <c>302</c>
2630   <c>Found</c>
2631   <c>
2632      <xref target="status.302"/>
2633   </c>
2634   <c>303</c>
2635   <c>See Other</c>
2636   <c>
2637      <xref target="status.303"/>
2638   </c>
2639   <c>305</c>
2640   <c>Use Proxy</c>
2641   <c>
2642      <xref target="status.305"/>
2643   </c>
2644   <c>306</c>
2645   <c>(Unused)</c>
2646   <c>
2647      <xref target="status.306"/>
2648   </c>
2649   <c>307</c>
2650   <c>Temporary Redirect</c>
2651   <c>
2652      <xref target="status.307"/>
2653   </c>
2654   <c>400</c>
2655   <c>Bad Request</c>
2656   <c>
2657      <xref target="status.400"/>
2658   </c>
2659   <c>402</c>
2660   <c>Payment Required</c>
2661   <c>
2662      <xref target="status.402"/>
2663   </c>
2664   <c>403</c>
2665   <c>Forbidden</c>
2666   <c>
2667      <xref target="status.403"/>
2668   </c>
2669   <c>404</c>
2670   <c>Not Found</c>
2671   <c>
2672      <xref target="status.404"/>
2673   </c>
2674   <c>405</c>
2675   <c>Method Not Allowed</c>
2676   <c>
2677      <xref target="status.405"/>
2678   </c>
2679   <c>406</c>
2680   <c>Not Acceptable</c>
2681   <c>
2682      <xref target="status.406"/>
2683   </c>
2684   <c>407</c>
2685   <c>Proxy Authentication Required</c>
2686   <c>
2687      <xref target="status.407"/>
2688   </c>
2689   <c>408</c>
2690   <c>Request Timeout</c>
2691   <c>
2692      <xref target="status.408"/>
2693   </c>
2694   <c>409</c>
2695   <c>Conflict</c>
2696   <c>
2697      <xref target="status.409"/>
2698   </c>
2699   <c>410</c>
2700   <c>Gone</c>
2701   <c>
2702      <xref target="status.410"/>
2703   </c>
2704   <c>411</c>
2705   <c>Length Required</c>
2706   <c>
2707      <xref target="status.411"/>
2708   </c>
2709   <c>413</c>
2710   <c>Request Entity Too Large</c>
2711   <c>
2712      <xref target="status.413"/>
2713   </c>
2714   <c>414</c>
2715   <c>URI Too Long</c>
2716   <c>
2717      <xref target="status.414"/>
2718   </c>
2719   <c>415</c>
2720   <c>Unsupported Media Type</c>
2721   <c>
2722      <xref target="status.415"/>
2723   </c>
2724   <c>417</c>
2725   <c>Expectation Failed</c>
2726   <c>
2727      <xref target="status.417"/>
2728   </c>
2729   <c>426</c>
2730   <c>Upgrade Required</c>
2731   <c>
2732      <xref target="status.426"/>
2733   </c>
2734   <c>500</c>
2735   <c>Internal Server Error</c>
2736   <c>
2737      <xref target="status.500"/>
2738   </c>
2739   <c>501</c>
2740   <c>Not Implemented</c>
2741   <c>
2742      <xref target="status.501"/>
2743   </c>
2744   <c>502</c>
2745   <c>Bad Gateway</c>
2746   <c>
2747      <xref target="status.502"/>
2748   </c>
2749   <c>503</c>
2750   <c>Service Unavailable</c>
2751   <c>
2752      <xref target="status.503"/>
2753   </c>
2754   <c>504</c>
2755   <c>Gateway Timeout</c>
2756   <c>
2757      <xref target="status.504"/>
2758   </c>
2759   <c>505</c>
2760   <c>HTTP Version Not Supported</c>
2761   <c>
2762      <xref target="status.505"/>
2763   </c>
2764</texttable>
2765<!--(END)-->
2766<?ENDINC p2-semantics.iana-status-codes ?>
2767</section>
2768<section title="Header Field Registration" anchor="header.field.registration">
2769<t>
2770   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
2771   with the permanent registrations below (see <xref target="RFC3864"/>):
2772</t>
2773<?BEGININC p2-semantics.iana-headers ?>
2774<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2775<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2776   <ttcol>Header Field Name</ttcol>
2777   <ttcol>Protocol</ttcol>
2778   <ttcol>Status</ttcol>
2779   <ttcol>Reference</ttcol>
2780
2781   <c>Allow</c>
2782   <c>http</c>
2783   <c>standard</c>
2784   <c>
2785      <xref target="header.allow"/>
2786   </c>
2787   <c>Expect</c>
2788   <c>http</c>
2789   <c>standard</c>
2790   <c>
2791      <xref target="header.expect"/>
2792   </c>
2793   <c>From</c>
2794   <c>http</c>
2795   <c>standard</c>
2796   <c>
2797      <xref target="header.from"/>
2798   </c>
2799   <c>Location</c>
2800   <c>http</c>
2801   <c>standard</c>
2802   <c>
2803      <xref target="header.location"/>
2804   </c>
2805   <c>Max-Forwards</c>
2806   <c>http</c>
2807   <c>standard</c>
2808   <c>
2809      <xref target="header.max-forwards"/>
2810   </c>
2811   <c>Referer</c>
2812   <c>http</c>
2813   <c>standard</c>
2814   <c>
2815      <xref target="header.referer"/>
2816   </c>
2817   <c>Retry-After</c>
2818   <c>http</c>
2819   <c>standard</c>
2820   <c>
2821      <xref target="header.retry-after"/>
2822   </c>
2823   <c>Server</c>
2824   <c>http</c>
2825   <c>standard</c>
2826   <c>
2827      <xref target="header.server"/>
2828   </c>
2829   <c>User-Agent</c>
2830   <c>http</c>
2831   <c>standard</c>
2832   <c>
2833      <xref target="header.user-agent"/>
2834   </c>
2835</texttable>
2836<!--(END)-->
2837<?ENDINC p2-semantics.iana-headers ?>
2838<t>
2839   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2840</t>
2841</section>
2842</section>
2843
2844<section title="Security Considerations" anchor="security.considerations">
2845<t>
2846   This section is meant to inform application developers, information
2847   providers, and users of the security limitations in HTTP/1.1 as
2848   described by this document. The discussion does not include
2849   definitive solutions to the problems revealed, though it does make
2850   some suggestions for reducing security risks.
2851</t>
2852
2853<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2854<t>
2855   Like any generic data transfer protocol, HTTP cannot regulate the
2856   content of the data that is transferred, nor is there any a priori
2857   method of determining the sensitivity of any particular piece of
2858   information within the context of any given request. Therefore,
2859   applications &SHOULD; supply as much control over this information as
2860   possible to the provider of that information. Four header fields are
2861   worth special mention in this context: Server, Via, Referer and From.
2862</t>
2863<t>
2864   Revealing the specific software version of the server might allow the
2865   server machine to become more vulnerable to attacks against software
2866   that is known to contain security holes. Implementors &SHOULD; make the
2867   Server header field a configurable option.
2868</t>
2869<t>
2870   Proxies which serve as a portal through a network firewall &SHOULD;
2871   take special precautions regarding the transfer of header information
2872   that identifies the hosts behind the firewall. In particular, they
2873   &SHOULD; remove, or replace with sanitized versions, any Via fields
2874   generated behind the firewall.
2875</t>
2876<t>
2877   The Referer header field allows reading patterns to be studied and reverse
2878   links drawn. Although it can be very useful, its power can be abused
2879   if user details are not separated from the information contained in
2880   the Referer. Even when the personal information has been removed, the
2881   Referer header field might indicate a private document's URI whose
2882   publication would be inappropriate.
2883</t>
2884<t>
2885   The information sent in the From field might conflict with the user's
2886   privacy interests or their site's security policy, and hence it
2887   &SHOULD-NOT;  be transmitted without the user being able to disable,
2888   enable, and modify the contents of the field. The user &MUST; be able
2889   to set the contents of this field within a user preference or
2890   application defaults configuration.
2891</t>
2892<t>
2893   We suggest, though do not require, that a convenient toggle interface
2894   be provided for the user to enable or disable the sending of From and
2895   Referer information.
2896</t>
2897<t>
2898   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref
2899   target="header.server"/>) header fields can sometimes be used to determine
2900   that a specific client or server have a particular security hole which might
2901   be exploited. Unfortunately, this same information is often used for other
2902   valuable purposes for which HTTP currently has no better mechanism.
2903</t>
2904<t>
2905   Furthermore, the User-Agent header field may contain enough entropy to be
2906   used, possibly in conjunction with other material, to uniquely identify the
2907   user.
2908</t>
2909<t>
2910   Some request methods, like TRACE (<xref target="TRACE"/>), expose information
2911   that was sent in request header fields within the body of their response.
2912   Clients &SHOULD; be careful with sensitive information, like Cookies,
2913   Authorization credentials, and other header fields that might be used to
2914   collect data from the client.
2915</t> 
2916</section>
2917
2918<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2919<t>
2920   Because the source of a link might be private information or might
2921   reveal an otherwise private information source, it is strongly
2922   recommended that the user be able to select whether or not the
2923   Referer field is sent. For example, a browser client could have a
2924   toggle switch for browsing openly/anonymously, which would
2925   respectively enable/disable the sending of Referer and From
2926   information.
2927</t>
2928<t>
2929   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2930   HTTP request if the referring page was transferred with a secure
2931   protocol.
2932</t>
2933<t>
2934   Authors of services &SHOULD-NOT; use GET-based forms for the submission of
2935   sensitive data because that data will be placed in the request-target. Many
2936   existing servers, proxies, and user agents log or display the request-target
2937   in places where it might be visible to third parties. Such services can
2938   use POST-based form submission instead.
2939</t>
2940</section>
2941
2942<section title="Location Headers and Spoofing" anchor="location.spoofing">
2943<t>
2944   If a single server supports multiple organizations that do not trust
2945   one another, then it &MUST; check the values of Location and Content-Location
2946   header fields in responses that are generated under control of
2947   said organizations to make sure that they do not attempt to
2948   invalidate resources over which they have no authority.
2949</t>
2950</section>
2951
2952<section title="Security Considerations for CONNECT">
2953<t>
2954   Since tunneled data is opaque to the proxy, there are additional
2955   risks to tunneling to other well-known or reserved ports.
2956   A HTTP client CONNECTing to port 25 could relay spam
2957   via SMTP, for example. As such, proxies &SHOULD; restrict CONNECT
2958   access to a small number of known ports.
2959</t>
2960</section>
2961
2962</section>
2963
2964<section title="Acknowledgments" anchor="ack">
2965</section>
2966</middle>
2967<back>
2968
2969<references title="Normative References">
2970
2971<reference anchor="Part1">
2972  <front>
2973    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2974    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2975      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
2976      <address><email>fielding@gbiv.com</email></address>
2977    </author>
2978    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2979      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2980      <address><email>jg@freedesktop.org</email></address>
2981    </author>
2982    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2983      <organization abbrev="HP">Hewlett-Packard Company</organization>
2984      <address><email>JeffMogul@acm.org</email></address>
2985    </author>
2986    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2987      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2988      <address><email>henrikn@microsoft.com</email></address>
2989    </author>
2990    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2991      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
2992      <address><email>LMM@acm.org</email></address>
2993    </author>
2994    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2995      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2996      <address><email>paulle@microsoft.com</email></address>
2997    </author>
2998    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2999      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3000      <address><email>timbl@w3.org</email></address>
3001    </author>
3002    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3003      <organization abbrev="W3C">World Wide Web Consortium</organization>
3004      <address><email>ylafon@w3.org</email></address>
3005    </author>
3006    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3007      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3008      <address><email>julian.reschke@greenbytes.de</email></address>
3009    </author>
3010    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3011  </front>
3012  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
3013  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
3014</reference>
3015
3016<reference anchor="Part3">
3017  <front>
3018    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
3019    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3020      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3021      <address><email>fielding@gbiv.com</email></address>
3022    </author>
3023    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3024      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3025      <address><email>jg@freedesktop.org</email></address>
3026    </author>
3027    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3028      <organization abbrev="HP">Hewlett-Packard Company</organization>
3029      <address><email>JeffMogul@acm.org</email></address>
3030    </author>
3031    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3032      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3033      <address><email>henrikn@microsoft.com</email></address>
3034    </author>
3035    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3036      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3037      <address><email>LMM@acm.org</email></address>
3038    </author>
3039    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3040      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3041      <address><email>paulle@microsoft.com</email></address>
3042    </author>
3043    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3044      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3045      <address><email>timbl@w3.org</email></address>
3046    </author>
3047    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3048      <organization abbrev="W3C">World Wide Web Consortium</organization>
3049      <address><email>ylafon@w3.org</email></address>
3050    </author>
3051    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3052      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3053      <address><email>julian.reschke@greenbytes.de</email></address>
3054    </author>
3055    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3056  </front>
3057  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
3058  <x:source href="p3-payload.xml" basename="p3-payload"/>
3059</reference>
3060
3061<reference anchor="Part4">
3062  <front>
3063    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
3064    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3065      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3066      <address><email>fielding@gbiv.com</email></address>
3067    </author>
3068    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3069      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3070      <address><email>jg@freedesktop.org</email></address>
3071    </author>
3072    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3073      <organization abbrev="HP">Hewlett-Packard Company</organization>
3074      <address><email>JeffMogul@acm.org</email></address>
3075    </author>
3076    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3077      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3078      <address><email>henrikn@microsoft.com</email></address>
3079    </author>
3080    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3081      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3082      <address><email>LMM@acm.org</email></address>
3083    </author>
3084    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3085      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3086      <address><email>paulle@microsoft.com</email></address>
3087    </author>
3088    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3089      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3090      <address><email>timbl@w3.org</email></address>
3091    </author>
3092    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3093      <organization abbrev="W3C">World Wide Web Consortium</organization>
3094      <address><email>ylafon@w3.org</email></address>
3095    </author>
3096    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3097      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3098      <address><email>julian.reschke@greenbytes.de</email></address>
3099    </author>
3100    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3101  </front>
3102  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
3103  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
3104</reference>
3105
3106<reference anchor="Part5">
3107  <front>
3108    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
3109    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3110      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3111      <address><email>fielding@gbiv.com</email></address>
3112    </author>
3113    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3114      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3115      <address><email>jg@freedesktop.org</email></address>
3116    </author>
3117    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3118      <organization abbrev="HP">Hewlett-Packard Company</organization>
3119      <address><email>JeffMogul@acm.org</email></address>
3120    </author>
3121    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3122      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3123      <address><email>henrikn@microsoft.com</email></address>
3124    </author>
3125    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3126      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3127      <address><email>LMM@acm.org</email></address>
3128    </author>
3129    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3130      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3131      <address><email>paulle@microsoft.com</email></address>
3132    </author>
3133    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3134      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3135      <address><email>timbl@w3.org</email></address>
3136    </author>
3137    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3138      <organization abbrev="W3C">World Wide Web Consortium</organization>
3139      <address><email>ylafon@w3.org</email></address>
3140    </author>
3141    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3142      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3143      <address><email>julian.reschke@greenbytes.de</email></address>
3144    </author>
3145    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3146  </front>
3147  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
3148  <x:source href="p5-range.xml" basename="p5-range"/>
3149</reference>
3150
3151<reference anchor="Part6">
3152  <front>
3153    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
3154    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3155      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3156      <address><email>fielding@gbiv.com</email></address>
3157    </author>
3158    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3159      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3160      <address><email>jg@freedesktop.org</email></address>
3161    </author>
3162    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3163      <organization abbrev="HP">Hewlett-Packard Company</organization>
3164      <address><email>JeffMogul@acm.org</email></address>
3165    </author>
3166    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3167      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3168      <address><email>henrikn@microsoft.com</email></address>
3169    </author>
3170    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3171      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3172      <address><email>LMM@acm.org</email></address>
3173    </author>
3174    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3175      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3176      <address><email>paulle@microsoft.com</email></address>
3177    </author>
3178    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3179      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3180      <address><email>timbl@w3.org</email></address>
3181    </author>
3182    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3183      <organization abbrev="W3C">World Wide Web Consortium</organization>
3184      <address><email>ylafon@w3.org</email></address>
3185    </author>
3186    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
3187      <address><email>mnot@mnot.net</email></address>
3188    </author>
3189    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3190      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3191      <address><email>julian.reschke@greenbytes.de</email></address>
3192    </author>
3193    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3194  </front>
3195  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
3196  <x:source href="p6-cache.xml" basename="p6-cache"/>
3197</reference>
3198
3199<reference anchor="Part7">
3200  <front>
3201    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
3202    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3203      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3204      <address><email>fielding@gbiv.com</email></address>
3205    </author>
3206    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3207      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3208      <address><email>jg@freedesktop.org</email></address>
3209    </author>
3210    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3211      <organization abbrev="HP">Hewlett-Packard Company</organization>
3212      <address><email>JeffMogul@acm.org</email></address>
3213    </author>
3214    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3215      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3216      <address><email>henrikn@microsoft.com</email></address>
3217    </author>
3218    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3219      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3220      <address><email>LMM@acm.org</email></address>
3221    </author>
3222    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3223      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3224      <address><email>paulle@microsoft.com</email></address>
3225    </author>
3226    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3227      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3228      <address><email>timbl@w3.org</email></address>
3229    </author>
3230    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3231      <organization abbrev="W3C">World Wide Web Consortium</organization>
3232      <address><email>ylafon@w3.org</email></address>
3233    </author>
3234    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3235      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3236      <address><email>julian.reschke@greenbytes.de</email></address>
3237    </author>
3238    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3239  </front>
3240  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
3241  <x:source href="p7-auth.xml" basename="p7-auth"/>
3242</reference>
3243
3244<reference anchor="RFC2119">
3245  <front>
3246    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
3247    <author initials="S." surname="Bradner" fullname="Scott Bradner">
3248      <organization>Harvard University</organization>
3249      <address><email>sob@harvard.edu</email></address>
3250    </author>
3251    <date month="March" year="1997"/>
3252  </front>
3253  <seriesInfo name="BCP" value="14"/>
3254  <seriesInfo name="RFC" value="2119"/>
3255</reference>
3256
3257<reference anchor="RFC3986">
3258 <front>
3259  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
3260  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
3261    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3262    <address>
3263       <email>timbl@w3.org</email>
3264       <uri>http://www.w3.org/People/Berners-Lee/</uri>
3265    </address>
3266  </author>
3267  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
3268    <organization abbrev="Day Software">Day Software</organization>
3269    <address>
3270      <email>fielding@gbiv.com</email>
3271      <uri>http://roy.gbiv.com/</uri>
3272    </address>
3273  </author>
3274  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
3275    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
3276    <address>
3277      <email>LMM@acm.org</email>
3278      <uri>http://larry.masinter.net/</uri>
3279    </address>
3280  </author>
3281  <date month='January' year='2005'></date>
3282 </front>
3283 <seriesInfo name="STD" value="66"/>
3284 <seriesInfo name="RFC" value="3986"/>
3285</reference>
3286
3287<reference anchor="RFC5234">
3288  <front>
3289    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
3290    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3291      <organization>Brandenburg InternetWorking</organization>
3292      <address>
3293        <email>dcrocker@bbiw.net</email>
3294      </address> 
3295    </author>
3296    <author initials="P." surname="Overell" fullname="Paul Overell">
3297      <organization>THUS plc.</organization>
3298      <address>
3299        <email>paul.overell@thus.net</email>
3300      </address>
3301    </author>
3302    <date month="January" year="2008"/>
3303  </front>
3304  <seriesInfo name="STD" value="68"/>
3305  <seriesInfo name="RFC" value="5234"/>
3306</reference>
3307
3308</references>
3309
3310<references title="Informative References">
3311
3312<reference anchor="RFC1945">
3313  <front>
3314    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3315    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3316      <organization>MIT, Laboratory for Computer Science</organization>
3317      <address><email>timbl@w3.org</email></address>
3318    </author>
3319    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3320      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3321      <address><email>fielding@ics.uci.edu</email></address>
3322    </author>
3323    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3324      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3325      <address><email>frystyk@w3.org</email></address>
3326    </author>
3327    <date month="May" year="1996"/>
3328  </front>
3329  <seriesInfo name="RFC" value="1945"/>
3330</reference>
3331
3332<reference anchor="RFC2068">
3333  <front>
3334    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3335    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3336      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3337      <address><email>fielding@ics.uci.edu</email></address>
3338    </author>
3339    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3340      <organization>MIT Laboratory for Computer Science</organization>
3341      <address><email>jg@w3.org</email></address>
3342    </author>
3343    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3344      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3345      <address><email>mogul@wrl.dec.com</email></address>
3346    </author>
3347    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3348      <organization>MIT Laboratory for Computer Science</organization>
3349      <address><email>frystyk@w3.org</email></address>
3350    </author>
3351    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3352      <organization>MIT Laboratory for Computer Science</organization>
3353      <address><email>timbl@w3.org</email></address>
3354    </author>
3355    <date month="January" year="1997"/>
3356  </front>
3357  <seriesInfo name="RFC" value="2068"/>
3358</reference>
3359
3360<reference anchor="RFC2616">
3361  <front>
3362    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3363    <author initials="R." surname="Fielding" fullname="R. Fielding">
3364      <organization>University of California, Irvine</organization>
3365      <address><email>fielding@ics.uci.edu</email></address>
3366    </author>
3367    <author initials="J." surname="Gettys" fullname="J. Gettys">
3368      <organization>W3C</organization>
3369      <address><email>jg@w3.org</email></address>
3370    </author>
3371    <author initials="J." surname="Mogul" fullname="J. Mogul">
3372      <organization>Compaq Computer Corporation</organization>
3373      <address><email>mogul@wrl.dec.com</email></address>
3374    </author>
3375    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3376      <organization>MIT Laboratory for Computer Science</organization>
3377      <address><email>frystyk@w3.org</email></address>
3378    </author>
3379    <author initials="L." surname="Masinter" fullname="L. Masinter">
3380      <organization>Xerox Corporation</organization>
3381      <address><email>masinter@parc.xerox.com</email></address>
3382    </author>
3383    <author initials="P." surname="Leach" fullname="P. Leach">
3384      <organization>Microsoft Corporation</organization>
3385      <address><email>paulle@microsoft.com</email></address>
3386    </author>
3387    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3388      <organization>W3C</organization>
3389      <address><email>timbl@w3.org</email></address>
3390    </author>
3391    <date month="June" year="1999"/>
3392  </front>
3393  <seriesInfo name="RFC" value="2616"/>
3394</reference>
3395
3396<reference anchor='RFC2817'>
3397  <front>
3398    <title>Upgrading to TLS Within HTTP/1.1</title>
3399    <author initials='R.' surname='Khare' fullname='R. Khare'>
3400      <organization>4K Associates / UC Irvine</organization>
3401      <address><email>rohit@4K-associates.com</email></address>
3402    </author>
3403    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3404      <organization>Agranat Systems, Inc.</organization>
3405      <address><email>lawrence@agranat.com</email></address>
3406    </author>
3407    <date year='2000' month='May' />
3408  </front>
3409  <seriesInfo name='RFC' value='2817' />
3410</reference>
3411
3412<reference anchor='RFC3864'>
3413  <front>
3414    <title>Registration Procedures for Message Header Fields</title>
3415    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3416      <organization>Nine by Nine</organization>
3417      <address><email>GK-IETF@ninebynine.org</email></address>
3418    </author>
3419    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3420      <organization>BEA Systems</organization>
3421      <address><email>mnot@pobox.com</email></address>
3422    </author>
3423    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3424      <organization>HP Labs</organization>
3425      <address><email>JeffMogul@acm.org</email></address>
3426    </author>
3427    <date year='2004' month='September' />
3428  </front>
3429  <seriesInfo name='BCP' value='90' />
3430  <seriesInfo name='RFC' value='3864' />
3431</reference>
3432
3433<reference anchor='RFC5226'>
3434  <front>
3435    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3436    <author initials='T.' surname='Narten' fullname='T. Narten'>
3437      <organization>IBM</organization>
3438      <address><email>narten@us.ibm.com</email></address>
3439    </author>
3440    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3441      <organization>Google</organization>
3442      <address><email>Harald@Alvestrand.no</email></address>
3443    </author>
3444    <date year='2008' month='May' />
3445  </front>
3446  <seriesInfo name='BCP' value='26' />
3447  <seriesInfo name='RFC' value='5226' />
3448</reference>
3449
3450<reference anchor="RFC5322">
3451  <front>
3452    <title>Internet Message Format</title>
3453    <author initials="P." surname="Resnick" fullname="P. Resnick">
3454      <organization>Qualcomm Incorporated</organization>
3455    </author>
3456    <date year="2008" month="October"/>
3457  </front> 
3458  <seriesInfo name="RFC" value="5322"/>
3459</reference>
3460
3461<reference anchor='RFC5789'>
3462  <front>
3463    <title>PATCH Method for HTTP</title>
3464    <author initials='L.' surname='Dusseault' fullname='L. Dusseault'>
3465      <organization>Linden Lab</organization>
3466    </author>
3467    <author initials='J.' surname='Snell' fullname='J. Snell' />
3468    <date year='2010' month='March' />
3469  </front>
3470  <seriesInfo name='RFC' value='5789' />
3471</reference>
3472
3473</references>
3474
3475<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3476<t>
3477  This document takes over the Status Code Registry, previously defined
3478  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3479  (<xref target="status.code.registry"/>)
3480</t>
3481<t>
3482  Clarify definition of POST.
3483  (<xref target="POST"/>)
3484</t>
3485<t>
3486  Remove requirement to handle all Content-* header fields; ban use of
3487  Content-Range with PUT.
3488  (<xref target="PUT"/>)
3489</t>
3490<t>
3491  Take over definition of CONNECT method from <xref target="RFC2817"/>.
3492  (<xref target="CONNECT"/>)
3493</t>
3494<t>
3495  Failed to consider that there are
3496  many other request methods that are safe to automatically redirect,
3497  and further that the user agent is able to make that determination
3498  based on the request method semantics.
3499  (Sections <xref format="counter" target="status.301"/>,
3500  <xref format="counter" target="status.302"/> and
3501  <xref format="counter" target="status.307"/>)
3502</t>
3503<t>
3504  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3505  It used to indicate that the target resource must be accessed through the
3506  proxy given by the Location field. The Location field gave the URI of the
3507  proxy. The recipient was expected to repeat this single request via the proxy.
3508  (<xref target="status.305"/>)
3509</t>
3510<t>
3511  Define status 426 (Upgrade Required) (this was incorporated from
3512  <xref target="RFC2817"/>).
3513  (<xref target="status.426"/>)
3514</t>
3515<t>
3516  Reclassify "Allow" as response header field, removing the option to
3517  specify it in a PUT request.
3518  Relax the server requirement on the contents of the Allow header field and
3519  remove requirement on clients to always trust the header field value.
3520  (<xref target="header.allow"/>)
3521</t>
3522<t>
3523  Correct syntax of Location header field to allow URI references (including
3524  relative references and fragments), as referred symbol "absoluteURI" wasn't
3525  what was expected, and add some clarifications as to when use of fragments
3526  would not be appropriate.
3527  (<xref target="header.location"/>)
3528</t>
3529<t>
3530  Restrict Max-Forwards header field to OPTIONS and TRACE (previously,
3531  extension methods could have used it as well).
3532  (<xref target="header.max-forwards"/>)
3533</t>
3534<t>
3535  Allow Referer field value of "about:blank" as alternative to not specifying it.
3536  (<xref target="header.referer"/>)
3537</t>
3538<t>
3539  In the description of the Server header field, the Via field
3540  was described as a SHOULD. The requirement was and is stated
3541  correctly in the description of the Via header field in &header-via;.
3542  (<xref target="header.server"/>)
3543</t>
3544</section>
3545
3546<?BEGININC p2-semantics.abnf-appendix ?>
3547<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3548<figure>
3549<artwork type="abnf" name="p2-semantics.parsed-abnf">
3550<x:ref>Allow</x:ref> = "Allow:" OWS Allow-v
3551<x:ref>Allow-v</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3552
3553<x:ref>Expect</x:ref> = "Expect:" OWS Expect-v
3554<x:ref>Expect-v</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3555
3556<x:ref>From</x:ref> = "From:" OWS From-v
3557<x:ref>From-v</x:ref> = mailbox
3558
3559<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3560
3561<x:ref>Location</x:ref> = "Location:" OWS Location-v
3562<x:ref>Location-v</x:ref> = URI-reference
3563
3564<x:ref>Max-Forwards</x:ref> = "Max-Forwards:" OWS Max-Forwards-v
3565<x:ref>Max-Forwards-v</x:ref> = 1*DIGIT
3566<x:ref>Method</x:ref> = token
3567
3568<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3569
3570<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3571<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3572<x:ref>Referer</x:ref> = "Referer:" OWS Referer-v
3573<x:ref>Referer-v</x:ref> = absolute-URI / partial-URI
3574<x:ref>Retry-After</x:ref> = "Retry-After:" OWS Retry-After-v
3575<x:ref>Retry-After-v</x:ref> = HTTP-date / delta-seconds
3576
3577<x:ref>Server</x:ref> = "Server:" OWS Server-v
3578<x:ref>Server-v</x:ref> = product *( RWS ( product / comment ) )
3579<x:ref>Status-Code</x:ref> = 3DIGIT
3580
3581<x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in [Part1], Section 2.6&gt;
3582<x:ref>User-Agent</x:ref> = "User-Agent:" OWS User-Agent-v
3583<x:ref>User-Agent-v</x:ref> = product *( RWS ( product / comment ) )
3584
3585<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
3586
3587<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3588
3589<x:ref>delta-seconds</x:ref> = 1*DIGIT
3590
3591<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3592<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3593<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3594 *expect-params ]
3595
3596<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3597
3598<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3599
3600<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
3601<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3602
3603<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3604
3605<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3606</artwork>
3607</figure>
3608<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3609; Allow defined but not used
3610; Expect defined but not used
3611; From defined but not used
3612; Location defined but not used
3613; Max-Forwards defined but not used
3614; Reason-Phrase defined but not used
3615; Referer defined but not used
3616; Retry-After defined but not used
3617; Server defined but not used
3618; Status-Code defined but not used
3619; User-Agent defined but not used
3620</artwork></figure></section>
3621<?ENDINC p2-semantics.abnf-appendix ?>
3622
3623<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3624
3625<section title="Since RFC 2616">
3626<t>
3627  Extracted relevant partitions from <xref target="RFC2616"/>.
3628</t>
3629</section>
3630
3631<section title="Since draft-ietf-httpbis-p2-semantics-00">
3632<t>
3633  Closed issues:
3634  <list style="symbols"> 
3635    <t>
3636      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3637      "Via is a MUST"
3638      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3639    </t>
3640    <t>
3641      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3642      "Fragments allowed in Location"
3643      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3644    </t>
3645    <t>
3646      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3647      "Safe Methods vs Redirection"
3648      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3649    </t>
3650    <t>
3651      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3652      "Revise description of the POST method"
3653      (<eref target="http://purl.org/NET/http-errata#post"/>)
3654    </t>
3655    <t>
3656      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3657      "Normative and Informative references"
3658    </t>
3659    <t>
3660      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3661      "RFC2606 Compliance"
3662    </t>
3663    <t>
3664      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3665      "Informative references"
3666    </t>
3667    <t>
3668      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3669      "Redundant cross-references"
3670    </t>
3671  </list>
3672</t>
3673<t>
3674  Other changes:
3675  <list style="symbols"> 
3676    <t>
3677      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3678    </t>
3679  </list>
3680</t>
3681</section>
3682
3683<section title="Since draft-ietf-httpbis-p2-semantics-01">
3684<t>
3685  Closed issues:
3686  <list style="symbols"> 
3687    <t>
3688      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3689      "PUT side effects"
3690    </t>
3691    <t>
3692      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3693      "Duplicate Host header requirements"
3694    </t>
3695  </list>
3696</t>
3697<t>
3698  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3699  <list style="symbols"> 
3700    <t>
3701      Move "Product Tokens" section (back) into Part 1, as "token" is used
3702      in the definition of the Upgrade header field.
3703    </t>
3704    <t>
3705      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3706    </t>
3707    <t>
3708      Copy definition of delta-seconds from Part6 instead of referencing it.
3709    </t>
3710  </list>
3711</t>
3712</section>
3713
3714<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3715<t>
3716  Closed issues:
3717  <list style="symbols"> 
3718    <t>
3719      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3720      "Requiring Allow in 405 responses"
3721    </t>
3722    <t>
3723      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3724      "Status Code Registry"
3725    </t>
3726    <t>
3727      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3728      "Redirection vs. Location"
3729    </t>
3730    <t>
3731      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3732      "Cacheability of 303 response"
3733    </t>
3734    <t>
3735      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3736      "305 Use Proxy"
3737    </t>
3738    <t>
3739      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3740      "Classification for Allow header"
3741    </t>
3742    <t>
3743      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3744      "PUT - 'store under' vs 'store at'"
3745    </t>
3746  </list>
3747</t>
3748<t>
3749  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3750  <list style="symbols"> 
3751    <t>
3752      Reference RFC 3984, and update header field registrations for headers defined
3753      in this document.
3754    </t>
3755  </list>
3756</t>
3757<t>
3758  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3759  <list style="symbols"> 
3760    <t>
3761      Replace string literals when the string really is case-sensitive (method).
3762    </t>
3763  </list>
3764</t>
3765</section>
3766
3767<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3768<t>
3769  Closed issues:
3770  <list style="symbols"> 
3771    <t>
3772      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3773      "OPTIONS request bodies"
3774    </t>
3775    <t>
3776      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3777      "Description of CONNECT should refer to RFC2817"
3778    </t>
3779    <t>
3780      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3781      "Location Content-Location reference request/response mixup"
3782    </t>
3783  </list>
3784</t>
3785<t>
3786  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3787  <list style="symbols"> 
3788    <t>
3789      Added initial proposal for registration process, plus initial
3790      content (non-HTTP/1.1 methods to be added by a separate specification).
3791    </t>
3792  </list>
3793</t>
3794</section>
3795
3796<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3797<t>
3798  Closed issues:
3799  <list style="symbols"> 
3800    <t>
3801      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3802      "Content-*"
3803    </t>
3804    <t>
3805      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3806      "RFC 2822 is updated by RFC 5322"
3807    </t>
3808  </list>
3809</t>
3810<t>
3811  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3812  <list style="symbols"> 
3813    <t>
3814      Use "/" instead of "|" for alternatives.
3815    </t>
3816    <t>
3817      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3818      whitespace ("OWS") and required whitespace ("RWS").
3819    </t>
3820    <t>
3821      Rewrite ABNFs to spell out whitespace rules, factor out
3822      header field value format definitions.
3823    </t>
3824  </list>
3825</t>
3826</section>
3827
3828<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3829<t>
3830  Closed issues:
3831  <list style="symbols"> 
3832    <t>
3833      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3834      "Reason-Phrase BNF"
3835    </t>
3836  </list>
3837</t>
3838<t>
3839  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3840  <list style="symbols"> 
3841    <t>
3842      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3843    </t>
3844  </list>
3845</t>
3846</section>
3847
3848<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3849<t>
3850  Closed issues:
3851  <list style="symbols"> 
3852    <t>
3853      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3854      "Clarify when Referer is sent"
3855    </t>
3856    <t>
3857      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3858      "status codes vs methods"
3859    </t>
3860    <t>
3861      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3862      "Do not require "updates" relation for specs that register status codes or method names"
3863    </t>
3864  </list>
3865</t>
3866</section>
3867
3868<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3869<t>
3870  Closed issues:
3871  <list style="symbols"> 
3872    <t>
3873      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3874      "Idempotency"
3875    </t>
3876    <t>
3877      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3878      "TRACE security considerations"
3879    </t>
3880    <t>
3881      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3882      "Clarify rules for determining what entities a response carries"
3883    </t>
3884    <t>
3885      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3886      "update note citing RFC 1945 and 2068"
3887    </t>
3888    <t>
3889      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3890      "update note about redirect limit"
3891    </t>
3892    <t>
3893      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3894      "Location header ABNF should use 'URI'"
3895    </t>
3896    <t>
3897      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3898      "fragments in Location vs status 303"
3899    </t>
3900    <t>
3901      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
3902      "move IANA registrations for optional status codes"
3903    </t>
3904  </list>
3905</t>
3906<t>
3907  Partly resolved issues:
3908  <list style="symbols"> 
3909    <t>
3910      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/171"/>:
3911      "Are OPTIONS and TRACE safe?"
3912    </t>
3913  </list>
3914</t>
3915</section>
3916
3917<section title="Since draft-ietf-httpbis-p2-semantics-08" anchor="changes.since.08">
3918<t>
3919  Closed issues:
3920  <list style="symbols"> 
3921    <t>
3922      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3923      "Safe Methods vs Redirection" (we missed the introduction to the 3xx
3924      status codes when fixing this previously)
3925    </t>
3926  </list>
3927</t>
3928</section>
3929
3930<section title="Since draft-ietf-httpbis-p2-semantics-09" anchor="changes.since.09">
3931<t>
3932  Closed issues:
3933  <list style="symbols"> 
3934    <t>
3935      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
3936      "Fragment combination / precedence during redirects"
3937    </t>
3938  </list>
3939</t>
3940<t>
3941  Partly resolved issues:
3942  <list style="symbols"> 
3943    <t>
3944      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/185"/>:
3945      "Location header payload handling"
3946    </t>
3947    <t>
3948      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
3949      "Term for the requested resource's URI"
3950    </t>
3951  </list>
3952</t>
3953</section>
3954
3955<section title="Since draft-ietf-httpbis-p2-semantics-10" anchor="changes.since.10">
3956<t>
3957  Closed issues:
3958  <list style="symbols"> 
3959    <t>
3960      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
3961      "Clarify 'Requested Variant'"
3962    </t>
3963    <t>
3964      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
3965      "Clarify entity / representation / variant terminology"
3966    </t>
3967    <t>
3968      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/139"/>:
3969      "Methods and Caching"
3970    </t>
3971    <t>
3972      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/190"/>:
3973      "OPTIONS vs Max-Forwards"
3974    </t>
3975    <t>
3976      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/199"/>:
3977      "Status codes and caching"
3978    </t>
3979    <t>
3980      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
3981      "consider removing the 'changes from 2068' sections"
3982    </t>
3983  </list>
3984</t>
3985</section>
3986
3987<section title="Since draft-ietf-httpbis-p2-semantics-11" anchor="changes.since.11">
3988<t>
3989  Closed issues:
3990  <list style="symbols"> 
3991    <t>
3992      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/229"/>:
3993      "Considerations for new status codes"
3994    </t>
3995    <t>
3996      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/230"/>:
3997      "Considerations for new methods"
3998    </t>
3999    <t>
4000      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/232"/>:
4001      "User-Agent guidelines" (relating to the 'User-Agent' header field)
4002    </t>
4003  </list>
4004</t>
4005</section>
4006
4007<section title="Since draft-ietf-httpbis-p2-semantics-12" anchor="changes.since.12">
4008<t>
4009  Closed issues:
4010  <list style="symbols"> 
4011    <t>
4012      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
4013      "Fragment combination / precedence during redirects" (added warning
4014      about having a fragid on the redirect may cause inconvenience in
4015      some cases)
4016    </t>
4017    <t>
4018      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/79"/>:
4019      "Content-* vs. PUT"
4020    </t>
4021    <t>
4022      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/88"/>:
4023      "205 Bodies"
4024    </t>
4025    <t>
4026      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/102"/>:
4027      "Understanding Content-* on non-PUT requests"
4028    </t>
4029    <t>
4030      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
4031      "Content-*"
4032    </t>
4033    <t>
4034      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/104"/>:
4035      "Header type defaulting"
4036    </t>
4037    <t>
4038      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
4039      "PUT - 'store under' vs 'store at'"
4040    </t>
4041    <t>
4042      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/137"/>:
4043      "duplicate ABNF for Reason-Phrase"
4044    </t>
4045    <t>
4046      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/180"/>:
4047      "Note special status of Content-* prefix in header registration procedures"
4048    </t>
4049    <t>
4050      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/203"/>:
4051      "Max-Forwards vs extension methods"
4052    </t>
4053    <t>
4054      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/213"/>:
4055      "What is the value space of HTTP status codes?" (actually fixed in
4056      draft-ietf-httpbis-p2-semantics-11)
4057    </t>
4058    <t>
4059      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/224"/>:
4060      "Header Classification"
4061    </t>
4062    <t>
4063      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/225"/>:
4064      "PUT side effect: invalidation or just stale?"
4065    </t>
4066    <t>
4067      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/226"/>:
4068      "proxies not supporting certain methods"
4069    </t>
4070    <t>
4071      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/239"/>:
4072      "Migrate CONNECT from RFC2817 to p2"
4073    </t>
4074    <t>
4075      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/240"/>:
4076      "Migrate Upgrade details from RFC2817"
4077    </t>
4078    <t>
4079      <eref target="http://trac.tools.ietf.org/wg/httpbis/trac/ticket/267"/>:
4080      "clarify PUT semantics'"
4081    </t>
4082    <t>
4083      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/275"/>:
4084      "duplicate ABNF for 'Method'"
4085    </t>
4086    <t>
4087      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>:
4088      "untangle ABNFs for header fields"
4089    </t>
4090  </list>
4091</t>
4092</section>
4093
4094</section>
4095
4096</back>
4097</rfc>
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