source: draft-ietf-httpbis/latest/p2-semantics.xml @ 695

Last change on this file since 695 was 695, checked in by julian.reschke@…, 10 years ago

Clarify rules for determining what entities a response carries (see #110 #196)

  • Property svn:eol-style set to native
File size: 156.5 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 "September">
16  <!ENTITY ID-YEAR "2009">
17  <!ENTITY notation                   "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
18  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY payload                    "<xref target='Part3' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY conditional                "<xref target='Part4' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY range                      "<xref target='Part5' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY caching                    "<xref target='Part6' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY auth                       "<xref target='Part7' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY caching-combining-headers  "<xref target='Part6' x:rel='#combining.headers' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY content-negotiation        "<xref target='Part3' x:rel='#content.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY notation-abnf              "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY basic-rules                "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY uri                        "<xref target='Part1' x:rel='#uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY full-date                  "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY http-url                   "<xref target='Part1' x:rel='#http-url' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY http-version               "<xref target='Part1' x:rel='#http.version' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY use100                     "<xref target='Part1' x:rel='#use.of.the.100.status' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY qvalue                     "<xref target='Part3' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY header-accept              "<xref target='Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35  <!ENTITY header-accept-charset      "<xref target='Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY header-accept-encoding     "<xref target='Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY header-accept-language     "<xref target='Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY header-accept-ranges       "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY header-age                 "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY header-authorization       "<xref target='Part7' x:rel='#header.authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41  <!ENTITY header-cache-control       "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
42  <!ENTITY header-content-location    "<xref target='Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
43  <!ENTITY header-content-range       "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
44  <!ENTITY header-etag                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
45  <!ENTITY header-expires             "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
46  <!ENTITY header-fields              "<xref target='Part1' x:rel='#header.fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
47  <!ENTITY header-host                "<xref target='Part1' x:rel='#header.host' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
48  <!ENTITY header-if-match            "<xref target='Part4' x:rel='#header.if-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
49  <!ENTITY header-if-modified-since   "<xref target='Part4' x:rel='#header.if-modified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
50  <!ENTITY header-if-none-match       "<xref target='Part4' x:rel='#header.if-none-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
51  <!ENTITY header-if-range            "<xref target='Part5' x:rel='#header.if-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
52  <!ENTITY header-if-unmodified-since "<xref target='Part4' x:rel='#header.if-unmodified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
53  <!ENTITY header-pragma              "<xref target='Part6' x:rel='#header.pragma' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
54  <!ENTITY header-proxy-authenticate  "<xref target='Part7' x:rel='#header.proxy-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
55  <!ENTITY header-proxy-authorization "<xref target='Part7' x:rel='#header.proxy-authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
56  <!ENTITY header-range               "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
57  <!ENTITY header-upgrade             "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
58  <!ENTITY header-te                  "<xref target='Part1' x:rel='#header.upgrade' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
59  <!ENTITY header-vary                "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
60  <!ENTITY header-via                 "<xref target='Part1' x:rel='#header.via' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
61  <!ENTITY header-warning             "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
62  <!ENTITY header-www-authenticate    "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
63  <!ENTITY message-body               "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
64  <!ENTITY product-tokens             "<xref target='Part1' x:rel='#product.tokens' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
65  <!ENTITY media-type-message-http    "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
66]>
67<?rfc toc="yes" ?>
68<?rfc symrefs="yes" ?>
69<?rfc sortrefs="yes" ?>
70<?rfc compact="yes"?>
71<?rfc subcompact="no" ?>
72<?rfc linkmailto="no" ?>
73<?rfc editing="no" ?>
74<?rfc comments="yes"?>
75<?rfc inline="yes"?>
76<?rfc-ext allow-markup-in-artwork="yes" ?>
77<?rfc-ext include-references-in-index="yes" ?>
78<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
79     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
80     xmlns:x='http://purl.org/net/xml2rfc/ext'
81     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
82<front>
83
84  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
85
86  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
87    <organization abbrev="Day Software">Day Software</organization>
88    <address>
89      <postal>
90        <street>23 Corporate Plaza DR, Suite 280</street>
91        <city>Newport Beach</city>
92        <region>CA</region>
93        <code>92660</code>
94        <country>USA</country>
95      </postal>
96      <phone>+1-949-706-5300</phone>
97      <facsimile>+1-949-706-5305</facsimile>
98      <email>fielding@gbiv.com</email>
99      <uri>http://roy.gbiv.com/</uri>
100    </address>
101  </author>
102
103  <author initials="J." surname="Gettys" fullname="Jim Gettys">
104    <organization>One Laptop per Child</organization>
105    <address>
106      <postal>
107        <street>21 Oak Knoll Road</street>
108        <city>Carlisle</city>
109        <region>MA</region>
110        <code>01741</code>
111        <country>USA</country>
112      </postal>
113      <email>jg@laptop.org</email>
114      <uri>http://www.laptop.org/</uri>
115    </address>
116  </author>
117 
118  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
119    <organization abbrev="HP">Hewlett-Packard Company</organization>
120    <address>
121      <postal>
122        <street>HP Labs, Large Scale Systems Group</street>
123        <street>1501 Page Mill Road, MS 1177</street>
124        <city>Palo Alto</city>
125        <region>CA</region>
126        <code>94304</code>
127        <country>USA</country>
128      </postal>
129      <email>JeffMogul@acm.org</email>
130    </address>
131  </author>
132
133  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
134    <organization abbrev="Microsoft">Microsoft Corporation</organization>
135    <address>
136      <postal>
137        <street>1 Microsoft Way</street>
138        <city>Redmond</city>
139        <region>WA</region>
140        <code>98052</code>
141        <country>USA</country>
142      </postal>
143      <email>henrikn@microsoft.com</email>
144    </address>
145  </author>
146
147  <author initials="L." surname="Masinter" fullname="Larry Masinter">
148    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
149    <address>
150      <postal>
151        <street>345 Park Ave</street>
152        <city>San Jose</city>
153        <region>CA</region>
154        <code>95110</code>
155        <country>USA</country>
156      </postal>
157      <email>LMM@acm.org</email>
158      <uri>http://larry.masinter.net/</uri>
159    </address>
160  </author>
161 
162  <author initials="P." surname="Leach" fullname="Paul J. Leach">
163    <organization abbrev="Microsoft">Microsoft Corporation</organization>
164    <address>
165      <postal>
166        <street>1 Microsoft Way</street>
167        <city>Redmond</city>
168        <region>WA</region>
169        <code>98052</code>
170      </postal>
171      <email>paulle@microsoft.com</email>
172    </address>
173  </author>
174   
175  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
176    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
177    <address>
178      <postal>
179        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
180        <street>The Stata Center, Building 32</street>
181        <street>32 Vassar Street</street>
182        <city>Cambridge</city>
183        <region>MA</region>
184        <code>02139</code>
185        <country>USA</country>
186      </postal>
187      <email>timbl@w3.org</email>
188      <uri>http://www.w3.org/People/Berners-Lee/</uri>
189    </address>
190  </author>
191
192  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
193    <organization abbrev="W3C">World Wide Web Consortium</organization>
194    <address>
195      <postal>
196        <street>W3C / ERCIM</street>
197        <street>2004, rte des Lucioles</street>
198        <city>Sophia-Antipolis</city>
199        <region>AM</region>
200        <code>06902</code>
201        <country>France</country>
202      </postal>
203      <email>ylafon@w3.org</email>
204      <uri>http://www.raubacapeu.net/people/yves/</uri>
205    </address>
206  </author>
207
208  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
209    <organization abbrev="greenbytes">greenbytes GmbH</organization>
210    <address>
211      <postal>
212        <street>Hafenweg 16</street>
213        <city>Muenster</city><region>NW</region><code>48155</code>
214        <country>Germany</country>
215      </postal>
216      <phone>+49 251 2807760</phone>
217      <facsimile>+49 251 2807761</facsimile>
218      <email>julian.reschke@greenbytes.de</email>
219      <uri>http://greenbytes.de/tech/webdav/</uri>
220    </address>
221  </author>
222
223  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
224  <workgroup>HTTPbis Working Group</workgroup>
225
226<abstract>
227<t>
228   The Hypertext Transfer Protocol (HTTP) is an application-level
229   protocol for distributed, collaborative, hypermedia information
230   systems. HTTP has been in use by the World Wide Web global information
231   initiative since 1990. This document is Part 2 of the seven-part specification
232   that defines the protocol referred to as "HTTP/1.1" and, taken together,
233   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
234   as expressed by request methods, request-header fields, response status codes,
235   and response-header fields.
236</t>
237</abstract>
238
239<note title="Editorial Note (To be removed by RFC Editor)">
240  <t>
241    Discussion of this draft should take place on the HTTPBIS working group
242    mailing list (ietf-http-wg@w3.org). The current issues list is
243    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/11"/>
244    and related documents (including fancy diffs) can be found at
245    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
246  </t>
247  <t>
248    The changes in this draft are summarized in <xref target="changes.since.07"/>.
249  </t>
250</note>
251</front>
252<middle>
253<section title="Introduction" anchor="introduction">
254<t>
255   This document defines HTTP/1.1 request and response semantics.  Each HTTP
256   message, as defined in &messaging;, is in the form of either a request or
257   a response.  An HTTP server listens on a connection for HTTP requests and
258   responds to each request, in the order received on that connection, with
259   one or more HTTP response messages.  This document defines the commonly
260   agreed upon semantics of the HTTP uniform interface, the intentions defined
261   by each request method, and the various response messages that might be
262   expected as a result of applying that method for the requested resource.
263</t>
264<t>
265   This document is currently disorganized in order to minimize the changes
266   between drafts and enable reviewers to see the smaller errata changes.
267   The next draft will reorganize the sections to better reflect the content.
268   In particular, the sections will be ordered according to the typical
269   processing of an HTTP request message (after message parsing): resource
270   mapping, general header fields, methods, request modifiers, response
271   status, and resource metadata.  The current mess reflects how widely
272   dispersed these topics and associated requirements had become in
273   <xref target="RFC2616"/>.
274</t>
275
276<section title="Requirements" anchor="intro.requirements">
277<t>
278   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
279   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
280   document are to be interpreted as described in <xref target="RFC2119"/>.
281</t>
282<t>
283   An implementation is not compliant if it fails to satisfy one or more
284   of the &MUST; or &REQUIRED; level requirements for the protocols it
285   implements. An implementation that satisfies all the &MUST; or &REQUIRED;
286   level and all the &SHOULD; level requirements for its protocols is said
287   to be "unconditionally compliant"; one that satisfies all the &MUST;
288   level requirements but not all the &SHOULD; level requirements for its
289   protocols is said to be "conditionally compliant."
290</t>
291</section>
292
293<section title="Syntax Notation" anchor="notation">
294  <x:anchor-alias value="CR"/>
295  <x:anchor-alias value="DIGIT"/>
296  <x:anchor-alias value="LF"/>
297  <x:anchor-alias value="VCHAR"/>
298  <x:anchor-alias value="WSP"/>
299<t>
300  This specification uses the ABNF syntax defined in &notation; (which
301  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
302  <xref target="collected.abnf"/> shows the collected ABNF, with the list
303  rule expanded.
304</t>
305<t>
306  The following core rules are included by
307  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
308  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
309  DIGIT (decimal 0-9), DQUOTE (double quote),
310  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
311  OCTET (any 8-bit sequence of data), SP (space),
312  VCHAR (any visible USASCII character),
313  and WSP (whitespace).
314</t>
315
316<section title="Core Rules" anchor="core.rules">
317  <x:anchor-alias value="obs-text"/>
318  <x:anchor-alias value="quoted-string"/>
319  <x:anchor-alias value="token"/>
320  <x:anchor-alias value="OWS"/>
321  <x:anchor-alias value="RWS"/>
322<t>
323  The core rules below are defined in &basic-rules;:
324</t>
325<figure><artwork type="abnf2616">
326  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
327  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
328  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
329  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
330  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
331</artwork></figure>
332</section>
333
334<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
335  <x:anchor-alias value="absolute-URI"/>
336  <x:anchor-alias value="Accept"/>
337  <x:anchor-alias value="Accept-Charset"/>
338  <x:anchor-alias value="Accept-Encoding"/>
339  <x:anchor-alias value="Accept-Language"/>
340  <x:anchor-alias value="Accept-Ranges"/>
341  <x:anchor-alias value="Age"/>
342  <x:anchor-alias value="Authorization"/>
343  <x:anchor-alias value="comment"/>
344  <x:anchor-alias value="ETag"/>
345  <x:anchor-alias value="Host"/>
346  <x:anchor-alias value="HTTP-date"/>
347  <x:anchor-alias value="If-Match"/>
348  <x:anchor-alias value="If-Modified-Since"/>
349  <x:anchor-alias value="If-None-Match"/>
350  <x:anchor-alias value="If-Range"/>
351  <x:anchor-alias value="If-Unmodified-Since"/>
352  <x:anchor-alias value="partial-URI"/>
353  <x:anchor-alias value="product"/>
354  <x:anchor-alias value="Proxy-Authenticate"/>
355  <x:anchor-alias value="Proxy-Authorization"/>
356  <x:anchor-alias value="Range"/>
357  <x:anchor-alias value="TE"/>
358  <x:anchor-alias value="URI"/>
359  <x:anchor-alias value="Vary"/>
360  <x:anchor-alias value="WWW-Authenticate"/>
361<t>
362  The ABNF rules below are defined in other parts:
363</t>
364<figure><!--Part1--><artwork type="abnf2616">
365  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
366  <x:ref>comment</x:ref>       = &lt;comment, defined in &header-fields;&gt;
367  <x:ref>Host</x:ref>          = &lt;Host, defined in &uri;&gt;
368  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
369  <x:ref>partial-URI</x:ref>   = &lt;partial-URI, defined in &uri;&gt;
370  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
371  <x:ref>TE</x:ref>            = &lt;TE, defined in &header-te;&gt;
372  <x:ref>URI</x:ref>           = &lt;URI, defined in &uri;&gt;
373</artwork></figure>
374<figure><!--Part3--><artwork type="abnf2616">
375  <x:ref>Accept</x:ref>        = &lt;Accept, defined in &header-accept;&gt;
376  <x:ref>Accept-Charset</x:ref> =
377             &lt;Accept-Charset, defined in &header-accept-charset;&gt;
378  <x:ref>Accept-Encoding</x:ref> =
379             &lt;Accept-Encoding, defined in &header-accept-encoding;&gt;
380  <x:ref>Accept-Language</x:ref> =
381             &lt;Accept-Language, defined in &header-accept-language;&gt;
382</artwork></figure>
383<figure><!--Part4--><artwork type="abnf2616">
384  <x:ref>ETag</x:ref>          = &lt;ETag, defined in &header-etag;&gt;
385  <x:ref>If-Match</x:ref>      = &lt;If-Match, defined in &header-if-match;&gt;
386  <x:ref>If-Modified-Since</x:ref> =
387             &lt;If-Modified-Since, defined in &header-if-modified-since;&gt;
388  <x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in &header-if-none-match;&gt;
389  <x:ref>If-Unmodified-Since</x:ref> =
390             &lt;If-Unmodified-Since, defined in &header-if-unmodified-since;&gt;
391</artwork></figure>
392<figure><!--Part5--><artwork type="abnf2616">
393  <x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in &header-accept-ranges;&gt;
394  <x:ref>If-Range</x:ref>      = &lt;If-Range, defined in &header-if-range;&gt;
395  <x:ref>Range</x:ref>         = &lt;Range, defined in &header-range;&gt;
396</artwork></figure>
397<figure><!--Part6--><artwork type="abnf2616">
398  <x:ref>Age</x:ref>           = &lt;Age, defined in &header-age;&gt;
399  <x:ref>Vary</x:ref>          = &lt;Vary, defined in &header-vary;&gt;
400</artwork><!--Part7--></figure>
401<figure><artwork type="abnf2616">
402  <x:ref>Authorization</x:ref> = &lt;Authorization, defined in &header-authorization;&gt;
403  <x:ref>Proxy-Authenticate</x:ref> =
404             &lt;Proxy-Authenticate, defined in &header-proxy-authenticate;&gt;
405  <x:ref>Proxy-Authorization</x:ref> =
406             &lt;Proxy-Authorization, defined in &header-proxy-authorization;&gt;
407  <x:ref>WWW-Authenticate</x:ref> =
408             &lt;WWW-Authenticate, defined in &header-www-authenticate;&gt;
409</artwork></figure>
410</section>
411</section>
412</section>
413
414<section title="Method" anchor="method">
415  <x:anchor-alias value="Method"/>
416  <x:anchor-alias value="extension-method"/>
417<t>
418   The Method  token indicates the method to be performed on the
419   resource identified by the request-target. The method is case-sensitive.
420</t>
421<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/><iref primary="true" item="Grammar" subitem="extension-method"/>
422  <x:ref>Method</x:ref>         = <x:abnf-char-sequence>"OPTIONS"</x:abnf-char-sequence>   ; "OPTIONS", <xref target="OPTIONS"/>
423                 / <x:abnf-char-sequence>"GET"</x:abnf-char-sequence>               ; "GET", <xref target="GET"/>
424                 / <x:abnf-char-sequence>"HEAD"</x:abnf-char-sequence>            ; "HEAD", <xref target="HEAD"/>
425                 / <x:abnf-char-sequence>"POST"</x:abnf-char-sequence>            ; "POST", <xref target="POST"/>
426                 / <x:abnf-char-sequence>"PUT"</x:abnf-char-sequence>               ; "PUT", <xref target="PUT"/>
427                 / <x:abnf-char-sequence>"DELETE"</x:abnf-char-sequence>      ; "DELETE", <xref target="DELETE"/>
428                 / <x:abnf-char-sequence>"TRACE"</x:abnf-char-sequence>         ; "TRACE", <xref target="TRACE"/>
429                 / <x:abnf-char-sequence>"CONNECT"</x:abnf-char-sequence>   ; "CONNECT", <xref target="CONNECT"/>
430                 / <x:ref>extension-method</x:ref>
431  <x:ref>extension-method</x:ref> = <x:ref>token</x:ref>
432</artwork></figure>
433<t>
434   The list of methods allowed by a resource can be specified in an
435   Allow header field (<xref target="header.allow"/>). The return code of the response
436   always notifies the client whether a method is currently allowed on a
437   resource, since the set of allowed methods can change dynamically. An
438   origin server &SHOULD; return the status code 405 (Method Not Allowed)
439   if the method is known by the origin server but not allowed for the
440   requested resource, and 501 (Not Implemented) if the method is
441   unrecognized or not implemented by the origin server. The methods GET
442   and HEAD &MUST; be supported by all general-purpose servers. All other
443   methods are &OPTIONAL;; however, if the above methods are implemented,
444   they &MUST; be implemented with the same semantics as those specified
445   in <xref target="method.definitions"/>.
446</t>
447
448<section title="Method Registry" anchor="method.registry">
449<t>
450  The HTTP Method Registry defines the name space for the Method token in the
451  Request line of an HTTP request.
452</t>
453<t>
454  Registrations &MUST; include the following fields:
455  <list style="symbols">
456    <t>Method Name (see <xref target="method"/>)</t>
457    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
458    <t>Pointer to specification text</t>
459  </list>
460</t>
461<t>
462  Values to be added to this name space are subject to IETF review
463  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
464</t>
465<t>
466  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
467</t>
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<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="request-header"/>
481  <x:ref>request-header</x:ref> = <x:ref>Accept</x:ref>                   ; &header-accept;
482                 / <x:ref>Accept-Charset</x:ref>           ; &header-accept-charset;
483                 / <x:ref>Accept-Encoding</x:ref>          ; &header-accept-encoding;
484                 / <x:ref>Accept-Language</x:ref>          ; &header-accept-language;
485                 / <x:ref>Authorization</x:ref>            ; &header-authorization;
486                 / <x:ref>Expect</x:ref>                   ; <xref target="header.expect"/>
487                 / <x:ref>From</x:ref>                     ; <xref target="header.from"/>
488                 / <x:ref>Host</x:ref>                     ; &header-host;
489                 / <x:ref>If-Match</x:ref>                 ; &header-if-match;
490                 / <x:ref>If-Modified-Since</x:ref>        ; &header-if-modified-since;
491                 / <x:ref>If-None-Match</x:ref>            ; &header-if-none-match;
492                 / <x:ref>If-Range</x:ref>                 ; &header-if-range;
493                 / <x:ref>If-Unmodified-Since</x:ref>      ; &header-if-unmodified-since;
494                 / <x:ref>Max-Forwards</x:ref>             ; <xref target="header.max-forwards"/>
495                 / <x:ref>Proxy-Authorization</x:ref>      ; &header-proxy-authorization;
496                 / <x:ref>Range</x:ref>                    ; &header-range;
497                 / <x:ref>Referer</x:ref>                  ; <xref target="header.referer"/>
498                 / <x:ref>TE</x:ref>                       ; &header-te;
499                 / <x:ref>User-Agent</x:ref>               ; <xref target="header.user-agent"/>
500</artwork></figure>
501<t>
502   Request-header field names can be extended reliably only in
503   combination with a change in the protocol version. However, new or
504   experimental header fields &MAY; be given the semantics of request-header
505   fields if all parties in the communication recognize them to
506   be request-header fields. Unrecognized header fields are treated as
507   entity-header fields.
508</t>
509</section>
510
511<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
512  <x:anchor-alias value="Reason-Phrase"/>
513  <x:anchor-alias value="Status-Code"/>
514  <x:anchor-alias value="extension-code"/>
515<t>
516   The Status-Code element is a 3-digit integer result code of the
517   attempt to understand and satisfy the request. The status codes listed
518   below are defined in <xref target="status.codes"/>.
519   The Reason-Phrase is intended to give a short
520   textual description of the Status-Code. The Status-Code is intended
521   for use by automata and the Reason-Phrase is intended for the human
522   user. The client is not required to examine or display the Reason-Phrase.
523</t>
524<t> 
525   The individual values of the numeric status codes defined for
526   HTTP/1.1, and an example set of corresponding Reason-Phrase's, are
527   presented below. The reason phrases listed here are only
528   recommendations -- they &MAY; be replaced by local equivalents without
529   affecting the protocol.
530</t>
531<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"/>
532  <x:ref>Status-Code</x:ref>    =
533         "100"  ; <xref target="status.100"/>: Continue
534       / "101"  ; <xref target="status.101"/>: Switching Protocols
535       / "200"  ; <xref target="status.200"/>: OK
536       / "201"  ; <xref target="status.201"/>: Created
537       / "202"  ; <xref target="status.202"/>: Accepted
538       / "203"  ; <xref target="status.203"/>: Non-Authoritative Information
539       / "204"  ; <xref target="status.204"/>: No Content
540       / "205"  ; <xref target="status.205"/>: Reset Content
541       / "206"  ; <xref target="status.206"/>: Partial Content
542       / "300"  ; <xref target="status.300"/>: Multiple Choices
543       / "301"  ; <xref target="status.301"/>: Moved Permanently
544       / "302"  ; <xref target="status.302"/>: Found
545       / "303"  ; <xref target="status.303"/>: See Other
546       / "304"  ; <xref target="status.304"/>: Not Modified
547       / "305"  ; <xref target="status.305"/>: Use Proxy
548       / "307"  ; <xref target="status.307"/>: Temporary Redirect
549       / "400"  ; <xref target="status.400"/>: Bad Request
550       / "401"  ; <xref target="status.401"/>: Unauthorized
551       / "402"  ; <xref target="status.402"/>: Payment Required
552       / "403"  ; <xref target="status.403"/>: Forbidden
553       / "404"  ; <xref target="status.404"/>: Not Found
554       / "405"  ; <xref target="status.405"/>: Method Not Allowed
555       / "406"  ; <xref target="status.406"/>: Not Acceptable
556       / "407"  ; <xref target="status.407"/>: Proxy Authentication Required
557       / "408"  ; <xref target="status.408"/>: Request Time-out
558       / "409"  ; <xref target="status.409"/>: Conflict
559       / "410"  ; <xref target="status.410"/>: Gone
560       / "411"  ; <xref target="status.411"/>: Length Required
561       / "412"  ; <xref target="status.412"/>: Precondition Failed
562       / "413"  ; <xref target="status.413"/>: Request Entity Too Large
563       / "414"  ; <xref target="status.414"/>: URI Too Long
564       / "415"  ; <xref target="status.415"/>: Unsupported Media Type
565       / "416"  ; <xref target="status.416"/>: Requested range not satisfiable
566       / "417"  ; <xref target="status.417"/>: Expectation Failed
567       / "500"  ; <xref target="status.500"/>: Internal Server Error
568       / "501"  ; <xref target="status.501"/>: Not Implemented
569       / "502"  ; <xref target="status.502"/>: Bad Gateway
570       / "503"  ; <xref target="status.503"/>: Service Unavailable
571       / "504"  ; <xref target="status.504"/>: Gateway Time-out
572       / "505"  ; <xref target="status.505"/>: HTTP Version not supported
573       / <x:ref>extension-code</x:ref>
574
575  <x:ref>extension-code</x:ref> = 3<x:ref>DIGIT</x:ref>
576  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
577</artwork></figure>
578<t>
579   HTTP status codes are extensible. HTTP applications are not required
580   to understand the meaning of all registered status codes, though such
581   understanding is obviously desirable. However, applications &MUST;
582   understand the class of any status code, as indicated by the first
583   digit, and treat any unrecognized response as being equivalent to the
584   x00 status code of that class, with the exception that an
585   unrecognized response &MUST-NOT; be cached. For example, if an
586   unrecognized status code of 431 is received by the client, it can
587   safely assume that there was something wrong with its request and
588   treat the response as if it had received a 400 status code. In such
589   cases, user agents &SHOULD; present to the user the entity returned
590   with the response, since that entity is likely to include human-readable
591   information which will explain the unusual status.
592</t>
593
594<section title="Status Code Registry" anchor="status.code.registry">
595<t>
596  The HTTP Status Code Registry defines the name space for the Status-Code
597  token in the Status line of an HTTP response.
598</t>
599<t>
600  Values to be added to this name space are subject to IETF review
601  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
602</t>
603<t>
604  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
605</t>
606</section>
607
608</section>
609
610<section title="Response Header Fields" anchor="response.header.fields">
611  <x:anchor-alias value="response-header"/>
612<t>
613   The response-header fields allow the server to pass additional
614   information about the response which cannot be placed in the Status-Line.
615   These header fields give information about the server and about
616   further access to the resource identified by the request-target.
617</t>
618<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="response-header"/>
619  <x:ref>response-header</x:ref> = <x:ref>Accept-Ranges</x:ref>           ; &header-accept-ranges;
620                  / <x:ref>Age</x:ref>                     ; &header-age;
621                  / <x:ref>Allow</x:ref>                   ; <xref target="header.allow"/>
622                  / <x:ref>ETag</x:ref>                    ; &header-etag;
623                  / <x:ref>Location</x:ref>                ; <xref target="header.location"/>
624                  / <x:ref>Proxy-Authenticate</x:ref>      ; &header-proxy-authenticate;
625                  / <x:ref>Retry-After</x:ref>             ; <xref target="header.retry-after"/>
626                  / <x:ref>Server</x:ref>                  ; <xref target="header.server"/>
627                  / <x:ref>Vary</x:ref>                    ; &header-vary;
628                  / <x:ref>WWW-Authenticate</x:ref>        ; &header-www-authenticate;
629</artwork></figure>
630<t>
631   Response-header field names can be extended reliably only in
632   combination with a change in the protocol version. However, new or
633   experimental header fields &MAY; be given the semantics of response-header
634   fields if all parties in the communication recognize them to
635   be response-header fields. Unrecognized header fields are treated as
636   entity-header fields.
637</t>
638</section>
639
640<section title="Entity" anchor="entity">
641<t>
642   Request and Response messages &MAY; transfer an entity if not otherwise
643   restricted by the request method or response status code. An entity
644   consists of entity-header fields and an entity-body, although some
645   responses will only include the entity-headers. HTTP entity-body and
646   entity-header fields are defined in &payload;.
647</t>
648<t>
649   An entity-body is only present in a message when a message-body is
650   present, as described in &message-body;. The entity-body is obtained
651   from the message-body by decoding any Transfer-Encoding that might
652   have been applied to ensure safe and proper transfer of the message.
653</t>
654
655<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
656<t>
657   It is sometimes necessary to determine the identity of the resource
658   associated with a representation.
659</t>
660<t>
661   An HTTP request representation, when present, is always associated with an
662   anonymous (i.e., unidentified) resource.
663</t>
664<t>
665   In the common case, an HTTP response is a representation of the resource
666   located at the request-URI. However, this is not always the case. To
667   determine the URI of the resource a response is associated with, the
668   following rules are used (first match winning):
669</t>
670<t><list style="numbers">
671   <t>If the response status code is 200 or 203 and the request method was GET,
672   the response is a representation of the resource at the request-URI.</t>
673   <t>If the response status is 204, 206, or 304 and the request method was GET
674   or HEAD, the response is a partial representation of the resource at the
675   request-URI (see &caching-combining-headers;).</t>
676   <t>If the response has a Content-Location header, and that URI is the same
677   as the request-URI <cref>(see [ref])</cref>, the response is a representation of the
678   resource at the request-URI.</t>
679   <t>If the response has a Content-Location header, and that URI is not the
680   same as the request-URI, the response asserts that it is a representation of
681   the resource at the Content-Location URI (but it may not be).</t>
682   <t>Otherwise, the response is a representation of an anonymous (i.e.,
683   unidentified) resource.</t>
684</list></t>
685<t>
686  <cref anchor="TODO-req-uri">
687   Note that 'request-URI' is used here; however, we need to come up with a
688   term to denote "the URI that can be inferred from examining the
689   request-target and the Host header." (see <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196" />).
690   Also, the comparison function is going to have to be defined somewhere,
691   because we already need to compare URIs for things like cache invalidation.</cref>
692</t>
693</section>
694
695</section>
696
697
698<section title="Method Definitions" anchor="method.definitions">
699<t>
700   The set of common methods for HTTP/1.1 is defined below. Although
701   this set can be expanded, additional methods cannot be assumed to
702   share the same semantics for separately extended clients and servers.
703</t>
704
705<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
706
707<section title="Safe Methods" anchor="safe.methods">
708<iref item="Safe Methods" primary="true"/>
709<t>
710   Implementors should be aware that the software represents the user in
711   their interactions over the Internet, and should be careful to allow
712   the user to be aware of any actions they might take which may have an
713   unexpected significance to themselves or others.
714</t>
715<t>
716   In particular, the convention has been established that the GET and
717   HEAD methods &SHOULD-NOT;  have the significance of taking an action
718   other than retrieval. These methods ought to be considered "<x:dfn anchor="safe">safe</x:dfn>".
719   This allows user agents to represent other methods, such as POST, PUT
720   and DELETE, in a special way, so that the user is made aware of the
721   fact that a possibly unsafe action is being requested.
722</t>
723<t>
724   Naturally, it is not possible to ensure that the server does not
725   generate side-effects as a result of performing a GET request; in
726   fact, some dynamic resources consider that a feature. The important
727   distinction here is that the user did not request the side-effects,
728   so therefore cannot be held accountable for them.
729</t>
730</section>
731
732<section title="Idempotent Methods" anchor="idempotent.methods">
733<iref item="Idempotent Methods" primary="true"/>
734<t>
735   Methods can also have the property of "idempotence" in that, aside
736   from error or expiration issues, the intended effect of multiple
737   identical requests is the same as for a single request.
738   The methods PUT, DELETE, and all safe methods are idempotent.
739   It is important to note that idempotence refers only to changes
740   requested by the client: a server is free to change its state due
741   to multiple requests for the purpose of tracking those requests,
742   versioning of results, etc.
743</t>
744</section>
745</section>
746
747<section title="OPTIONS" anchor="OPTIONS">
748  <rdf:Description>
749    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
750  </rdf:Description>
751  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
752  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
753<t>
754   The OPTIONS method represents a request for information about the
755   communication options available on the request/response chain
756   identified by the request-target. This method allows the client to
757   determine the options and/or requirements associated with a resource,
758   or the capabilities of a server, without implying a resource action
759   or initiating a resource retrieval.
760</t>
761<t>
762   Responses to this method are not cacheable.
763</t>
764<t>
765   If the OPTIONS request includes an entity-body (as indicated by the
766   presence of Content-Length or Transfer-Encoding), then the media type
767   &MUST; be indicated by a Content-Type field. Although this
768   specification does not define any use for such a body, future
769   extensions to HTTP might use the OPTIONS body to make more detailed
770   queries on the server.
771</t>
772<t>
773   If the request-target is an asterisk ("*"), the OPTIONS request is
774   intended to apply to the server in general rather than to a specific
775   resource. Since a server's communication options typically depend on
776   the resource, the "*" request is only useful as a "ping" or "no-op"
777   type of method; it does nothing beyond allowing the client to test
778   the capabilities of the server. For example, this can be used to test
779   a proxy for HTTP/1.1 compliance (or lack thereof).
780</t>
781<t>
782   If the request-target is not an asterisk, the OPTIONS request applies
783   only to the options that are available when communicating with that
784   resource.
785</t>
786<t>
787   A 200 response &SHOULD; include any header fields that indicate
788   optional features implemented by the server and applicable to that
789   resource (e.g., Allow), possibly including extensions not defined by
790   this specification. The response body, if any, &SHOULD; also include
791   information about the communication options. The format for such a
792   body is not defined by this specification, but might be defined by
793   future extensions to HTTP. Content negotiation &MAY; be used to select
794   the appropriate response format. If no response body is included, the
795   response &MUST; include a Content-Length field with a field-value of
796   "0".
797</t>
798<t>
799   The Max-Forwards request-header field &MAY; be used to target a
800   specific proxy in the request chain. When a proxy receives an OPTIONS
801   request on an absolute-URI for which request forwarding is permitted,
802   the proxy &MUST; check for a Max-Forwards field. If the Max-Forwards
803   field-value is zero ("0"), the proxy &MUST-NOT; forward the message;
804   instead, the proxy &SHOULD; respond with its own communication options.
805   If the Max-Forwards field-value is an integer greater than zero, the
806   proxy &MUST; decrement the field-value when it forwards the request. If
807   no Max-Forwards field is present in the request, then the forwarded
808   request &MUST-NOT; include a Max-Forwards field.
809</t>
810</section>
811
812<section title="GET" anchor="GET">
813  <rdf:Description>
814    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
815  </rdf:Description>
816  <iref primary="true" item="GET method" x:for-anchor=""/>
817  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
818<t>
819   The GET method means retrieve whatever information (in the form of an
820   entity) is identified by the request-target. If the request-target refers
821   to a data-producing process, it is the produced data which shall be
822   returned as the entity in the response and not the source text of the
823   process, unless that text happens to be the output of the process.
824</t>
825<t>
826   The semantics of the GET method change to a "conditional GET" if the
827   request message includes an If-Modified-Since, If-Unmodified-Since,
828   If-Match, If-None-Match, or If-Range header field. A conditional GET
829   method requests that the entity be transferred only under the
830   circumstances described by the conditional header field(s). The
831   conditional GET method is intended to reduce unnecessary network
832   usage by allowing cached entities to be refreshed without requiring
833   multiple requests or transferring data already held by the client.
834</t>
835<t>
836   The semantics of the GET method change to a "partial GET" if the
837   request message includes a Range header field. A partial GET requests
838   that only part of the entity be transferred, as described in &header-range;.
839   The partial GET method is intended to reduce unnecessary
840   network usage by allowing partially-retrieved entities to be
841   completed without transferring data already held by the client.
842</t>
843<t>
844   The response to a GET request is cacheable if and only if it meets
845   the requirements for HTTP caching described in &caching;.
846</t>
847<t>
848   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
849</t>
850</section>
851
852<section title="HEAD" anchor="HEAD">
853  <rdf:Description>
854    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
855  </rdf:Description>
856  <iref primary="true" item="HEAD method" x:for-anchor=""/>
857  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
858<t>
859   The HEAD method is identical to GET except that the server &MUST-NOT;
860   return a message-body in the response. The metainformation contained
861   in the HTTP headers in response to a HEAD request &SHOULD; be identical
862   to the information sent in response to a GET request. This method can
863   be used for obtaining metainformation about the entity implied by the
864   request without transferring the entity-body itself. This method is
865   often used for testing hypertext links for validity, accessibility,
866   and recent modification.
867</t>
868<t>
869   The response to a HEAD request &MAY; be cacheable in the sense that the
870   information contained in the response &MAY; be used to update a
871   previously cached entity from that resource. If the new field values
872   indicate that the cached entity differs from the current entity (as
873   would be indicated by a change in Content-Length, Content-MD5, ETag
874   or Last-Modified), then the cache &MUST; treat the cache entry as
875   stale.
876</t>
877</section>
878
879<section title="POST" anchor="POST">
880  <iref primary="true" item="POST method" x:for-anchor=""/>
881  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
882<t>
883   The POST method is used to request that the origin server accept the
884   entity enclosed in the request as data to be processed by the resource
885   identified by the request-target in the Request-Line. POST is designed
886   to allow a uniform method to cover the following functions:
887  <list style="symbols">
888    <t>
889      Annotation of existing resources;
890    </t>
891    <t>
892        Posting a message to a bulletin board, newsgroup, mailing list,
893        or similar group of articles;
894    </t>
895    <t>
896        Providing a block of data, such as the result of submitting a
897        form, to a data-handling process;
898    </t>
899    <t>
900        Extending a database through an append operation.
901    </t>
902  </list>
903</t>
904<t>
905   The actual function performed by the POST method is determined by the
906   server and is usually dependent on the request-target.
907</t>
908<t>
909   The action performed by the POST method might not result in a
910   resource that can be identified by a URI. In this case, either 200
911   (OK) or 204 (No Content) is the appropriate response status,
912   depending on whether or not the response includes an entity that
913   describes the result.
914</t>
915<t>
916   If a resource has been created on the origin server, the response
917   &SHOULD; be 201 (Created) and contain an entity which describes the
918   status of the request and refers to the new resource, and a Location
919   header (see <xref target="header.location"/>).
920</t>
921<t>
922   Responses to this method are not cacheable, unless the response
923   includes appropriate Cache-Control or Expires header fields. However,
924   the 303 (See Other) response can be used to direct the user agent to
925   retrieve a cacheable resource.
926</t>
927</section>
928
929<section title="PUT" anchor="PUT">
930  <iref primary="true" item="PUT method" x:for-anchor=""/>
931  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
932<t>
933   The PUT method requests that the enclosed entity be stored at the
934   supplied request-target. If the request-target refers to an already
935   existing resource, the enclosed entity &SHOULD; be considered as a
936   modified version of the one residing on the origin server. If the
937   request-target does not point to an existing resource, and that URI is
938   capable of being defined as a new resource by the requesting user
939   agent, the origin server can create the resource with that URI. If a
940   new resource is created at the request-target, the origin server &MUST;
941   inform the user agent
942   via the 201 (Created) response. If an existing resource is modified,
943   either the 200 (OK) or 204 (No Content) response codes &SHOULD; be sent
944   to indicate successful completion of the request. If the resource
945   could not be created or modified with the request-target, an appropriate
946   error response &SHOULD; be given that reflects the nature of the
947   problem. The recipient of the entity &MUST-NOT; ignore any Content-*
948   headers (headers starting with the prefix 'Content-') that it does
949   not understand or implement
950   and &MUST; return a 501 (Not Implemented) response in such cases.
951</t>
952<t>
953   If the request passes through a cache and the request-target identifies
954   one or more currently cached entities, those entries &SHOULD; be
955   treated as stale. Responses to this method are not cacheable.
956</t>
957<t>
958   The fundamental difference between the POST and PUT requests is
959   reflected in the different meaning of the request-target. The URI in a
960   POST request identifies the resource that will handle the enclosed
961   entity. That resource might be a data-accepting process, a gateway to
962   some other protocol, or a separate entity that accepts annotations.
963   In contrast, the URI in a PUT request identifies the entity enclosed
964   with the request -- the user agent knows what URI is intended and the
965   server &MUST-NOT; attempt to apply the request to some other resource.
966   If the server desires that the request be applied to a different URI,
967   it &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
968   then make its own decision regarding whether or not to redirect the
969   request.
970</t>
971<t>
972   A single resource &MAY; be identified by many different URIs. For
973   example, an article might have a URI for identifying "the current
974   version" which is separate from the URI identifying each particular
975   version. In this case, a PUT request on a general URI might result in
976   several other URIs being defined by the origin server.
977</t>
978<t>
979   HTTP/1.1 does not define how a PUT method affects the state of an
980   origin server.
981</t>
982<t>
983   Unless otherwise specified for a particular entity-header, the
984   entity-headers in the PUT request &SHOULD; be applied to the resource
985   created or modified by the PUT.
986</t>
987</section>
988
989<section title="DELETE" anchor="DELETE">
990  <iref primary="true" item="DELETE method" x:for-anchor=""/>
991  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
992<t>
993   The DELETE method requests that the origin server delete the resource
994   identified by the request-target. This method &MAY; be overridden by human
995   intervention (or other means) on the origin server. The client cannot
996   be guaranteed that the operation has been carried out, even if the
997   status code returned from the origin server indicates that the action
998   has been completed successfully. However, the server &SHOULD-NOT; 
999   indicate success unless, at the time the response is given, it
1000   intends to delete the resource or move it to an inaccessible
1001   location.
1002</t>
1003<t>
1004   A successful response &SHOULD; be 200 (OK) if the response includes an
1005   entity describing the status, 202 (Accepted) if the action has not
1006   yet been enacted, or 204 (No Content) if the action has been enacted
1007   but the response does not include an entity.
1008</t>
1009<t>
1010   If the request passes through a cache and the request-target identifies
1011   one or more currently cached entities, those entries &SHOULD; be
1012   treated as stale. Responses to this method are not cacheable.
1013</t>
1014</section>
1015
1016<section title="TRACE" anchor="TRACE">
1017  <rdf:Description>
1018    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1019  </rdf:Description>
1020  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1021  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1022<t>
1023   The TRACE method is used to invoke a remote, application-layer loop-back
1024   of the request message. The final recipient of the request
1025   &SHOULD; reflect the message received back to the client as the
1026   entity-body of a 200 (OK) response. The final recipient is either the
1027   origin server or the first proxy or gateway to receive a Max-Forwards
1028   value of zero (0) in the request (see <xref target="header.max-forwards"/>). A TRACE request
1029   &MUST-NOT; include an entity.
1030</t>
1031<t>
1032   TRACE allows the client to see what is being received at the other
1033   end of the request chain and use that data for testing or diagnostic
1034   information. The value of the Via header field (&header-via;) is of
1035   particular interest, since it acts as a trace of the request chain.
1036   Use of the Max-Forwards header field allows the client to limit the
1037   length of the request chain, which is useful for testing a chain of
1038   proxies forwarding messages in an infinite loop.
1039</t>
1040<t>
1041   If the request is valid, the response &SHOULD; contain the entire
1042   request message in the entity-body, with a Content-Type of
1043   "message/http" (see &media-type-message-http;). Responses to this method
1044   &MUST-NOT; be cached.
1045</t>
1046</section>
1047
1048<section title="CONNECT" anchor="CONNECT">
1049  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1050  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1051<t>
1052   This specification reserves the method name CONNECT for use with a
1053   proxy that can dynamically switch to being a tunnel (e.g. SSL
1054   tunneling <xref target="RFC2817"/>).
1055</t>
1056</section>
1057</section>
1058
1059
1060<section title="Status Code Definitions" anchor="status.codes">
1061<t>
1062   Each Status-Code is described below, including any metainformation required
1063   in the response.
1064</t>
1065
1066<section title="Informational 1xx" anchor="status.1xx">
1067<t>
1068   This class of status code indicates a provisional response,
1069   consisting only of the Status-Line and optional headers, and is
1070   terminated by an empty line. There are no required headers for this
1071   class of status code. Since HTTP/1.0 did not define any 1xx status
1072   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1073   except under experimental conditions.
1074</t>
1075<t>
1076   A client &MUST; be prepared to accept one or more 1xx status responses
1077   prior to a regular response, even if the client does not expect a 100
1078   (Continue) status message. Unexpected 1xx status responses &MAY; be
1079   ignored by a user agent.
1080</t>
1081<t>
1082   Proxies &MUST; forward 1xx responses, unless the connection between the
1083   proxy and its client has been closed, or unless the proxy itself
1084   requested the generation of the 1xx response. (For example, if a
1085   proxy adds a "Expect: 100-continue" field when it forwards a request,
1086   then it need not forward the corresponding 100 (Continue)
1087   response(s).)
1088</t>
1089
1090<section title="100 Continue" anchor="status.100">
1091  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1092  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1093<t>
1094   The client &SHOULD; continue with its request. This interim response is
1095   used to inform the client that the initial part of the request has
1096   been received and has not yet been rejected by the server. The client
1097   &SHOULD; continue by sending the remainder of the request or, if the
1098   request has already been completed, ignore this response. The server
1099   &MUST; send a final response after the request has been completed. See
1100   &use100; for detailed discussion of the use and handling of this
1101   status code.
1102</t>
1103</section>
1104
1105<section title="101 Switching Protocols" anchor="status.101">
1106  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1107  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1108<t>
1109   The server understands and is willing to comply with the client's
1110   request, via the Upgrade message header field (&header-upgrade;), for a
1111   change in the application protocol being used on this connection. The
1112   server will switch protocols to those defined by the response's
1113   Upgrade header field immediately after the empty line which
1114   terminates the 101 response.
1115</t>
1116<t>
1117   The protocol &SHOULD; be switched only when it is advantageous to do
1118   so. For example, switching to a newer version of HTTP is advantageous
1119   over older versions, and switching to a real-time, synchronous
1120   protocol might be advantageous when delivering resources that use
1121   such features.
1122</t>
1123</section>
1124</section>
1125
1126<section title="Successful 2xx" anchor="status.2xx">
1127<t>
1128   This class of status code indicates that the client's request was
1129   successfully received, understood, and accepted.
1130</t>
1131
1132<section title="200 OK" anchor="status.200">
1133  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1134  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1135<t>
1136   The request has succeeded. The information returned with the response
1137   is dependent on the method used in the request, for example:
1138  <list style="hanging">
1139    <t hangText="GET">
1140          an entity corresponding to the requested resource is sent in
1141          the response;
1142    </t>
1143    <t hangText="HEAD">
1144          the entity-header fields corresponding to the requested
1145          resource are sent in the response without any message-body;
1146    </t>
1147    <t hangText="POST">
1148      an entity describing or containing the result of the action;
1149    </t>
1150    <t hangText="TRACE">
1151      an entity containing the request message as received by the
1152      end server.
1153    </t>
1154  </list>
1155</t>
1156</section>
1157
1158<section title="201 Created" anchor="status.201">
1159  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1160  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1161<t>
1162   The request has been fulfilled and resulted in a new resource being
1163   created. The newly created resource can be referenced by the URI(s)
1164   returned in the entity of the response, with the most specific URI
1165   for the resource given by a Location header field. The response
1166   &SHOULD; include an entity containing a list of resource
1167   characteristics and location(s) from which the user or user agent can
1168   choose the one most appropriate. The entity format is specified by
1169   the media type given in the Content-Type header field. The origin
1170   server &MUST; create the resource before returning the 201 status code.
1171   If the action cannot be carried out immediately, the server &SHOULD;
1172   respond with 202 (Accepted) response instead.
1173</t>
1174<t>
1175   A 201 response &MAY; contain an ETag response header field indicating
1176   the current value of the entity tag for the requested variant just
1177   created, see &header-etag;.
1178</t>
1179</section>
1180
1181<section title="202 Accepted" anchor="status.202">
1182  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1183  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1184<t>
1185   The request has been accepted for processing, but the processing has
1186   not been completed.  The request might or might not eventually be
1187   acted upon, as it might be disallowed when processing actually takes
1188   place. There is no facility for re-sending a status code from an
1189   asynchronous operation such as this.
1190</t>
1191<t>
1192   The 202 response is intentionally non-committal. Its purpose is to
1193   allow a server to accept a request for some other process (perhaps a
1194   batch-oriented process that is only run once per day) without
1195   requiring that the user agent's connection to the server persist
1196   until the process is completed. The entity returned with this
1197   response &SHOULD; include an indication of the request's current status
1198   and either a pointer to a status monitor or some estimate of when the
1199   user can expect the request to be fulfilled.
1200</t>
1201</section>
1202
1203<section title="203 Non-Authoritative Information" anchor="status.203">
1204  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1205  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1206<t>
1207   The returned metainformation in the entity-header is not the
1208   definitive set as available from the origin server, but is gathered
1209   from a local or a third-party copy. The set presented &MAY; be a subset
1210   or superset of the original version. For example, including local
1211   annotation information about the resource might result in a superset
1212   of the metainformation known by the origin server. Use of this
1213   response code is not required and is only appropriate when the
1214   response would otherwise be 200 (OK).
1215</t>
1216</section>
1217
1218<section title="204 No Content" anchor="status.204">
1219  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1220  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1221<t>
1222   The server has fulfilled the request but does not need to return an
1223   entity-body, and might want to return updated metainformation. The
1224   response &MAY; include new or updated metainformation in the form of
1225   entity-headers, which if present &SHOULD; be associated with the
1226   requested variant.
1227</t>
1228<t>
1229   If the client is a user agent, it &SHOULD-NOT;  change its document view
1230   from that which caused the request to be sent. This response is
1231   primarily intended to allow input for actions to take place without
1232   causing a change to the user agent's active document view, although
1233   any new or updated metainformation &SHOULD; be applied to the document
1234   currently in the user agent's active view.
1235</t>
1236<t>
1237   The 204 response &MUST-NOT; include a message-body, and thus is always
1238   terminated by the first empty line after the header fields.
1239</t>
1240</section>
1241
1242<section title="205 Reset Content" anchor="status.205">
1243  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1244  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1245<t>
1246   The server has fulfilled the request and the user agent &SHOULD; reset
1247   the document view which caused the request to be sent. This response
1248   is primarily intended to allow input for actions to take place via
1249   user input, followed by a clearing of the form in which the input is
1250   given so that the user can easily initiate another input action. The
1251   response &MUST-NOT; include an entity.
1252</t>
1253</section>
1254
1255<section title="206 Partial Content" anchor="status.206">
1256  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1257  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1258<t>
1259   The server has fulfilled the partial GET request for the resource
1260   and the enclosed entity is a partial representation as defined in &range;.
1261</t>
1262</section>
1263</section>
1264
1265<section title="Redirection 3xx" anchor="status.3xx">
1266<t>
1267   This class of status code indicates that further action needs to be
1268   taken by the user agent in order to fulfill the request.  The action
1269   required &MAY; be carried out by the user agent without interaction
1270   with the user if and only if the method used in the second request is
1271   GET or HEAD. A client &SHOULD; detect infinite redirection loops, since
1272   such loops generate network traffic for each redirection.
1273</t>
1274<x:note>
1275  <t>
1276    <x:h>Note:</x:h> an earlier version of this specification recommended a
1277    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1278    Content developers should be aware that there might be clients that
1279    implement such a fixed limitation.
1280  </t>
1281</x:note>
1282
1283<section title="300 Multiple Choices" anchor="status.300">
1284  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1285  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1286<t>
1287   The requested resource corresponds to any one of a set of
1288   representations, each with its own specific location, and agent-driven
1289   negotiation information (&content-negotiation;) is being provided so that
1290   the user (or user agent) can select a preferred representation and
1291   redirect its request to that location.
1292</t>
1293<t>
1294   Unless it was a HEAD request, the response &SHOULD; include an entity
1295   containing a list of resource characteristics and location(s) from
1296   which the user or user agent can choose the one most appropriate. The
1297   entity format is specified by the media type given in the Content-Type
1298   header field. Depending upon the format and the capabilities of
1299   the user agent, selection of the most appropriate choice &MAY; be
1300   performed automatically. However, this specification does not define
1301   any standard for such automatic selection.
1302</t>
1303<t>
1304   If the server has a preferred choice of representation, it &SHOULD;
1305   include the specific URI for that representation in the Location
1306   field; user agents &MAY; use the Location field value for automatic
1307   redirection. This response is cacheable unless indicated otherwise.
1308</t>
1309</section>
1310
1311<section title="301 Moved Permanently" anchor="status.301">
1312  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1313  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1314<t>
1315   The requested resource has been assigned a new permanent URI and any
1316   future references to this resource &SHOULD; use one of the returned
1317   URIs.  Clients with link editing capabilities ought to automatically
1318   re-link references to the request-target to one or more of the new
1319   references returned by the server, where possible. This response is
1320   cacheable unless indicated otherwise.
1321</t>
1322<t>
1323   The new permanent URI &SHOULD; be given by the Location field in the
1324   response. Unless the request method was HEAD, the entity of the
1325   response &SHOULD; contain a short hypertext note with a hyperlink to
1326   the new URI(s).
1327</t>
1328<t>
1329   If the 301 status code is received in response to a request method
1330   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1331   then the request &MAY; be automatically redirected by the user agent without
1332   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1333   request unless it can be confirmed by the user, since this might
1334   change the conditions under which the request was issued.
1335</t>
1336<x:note>
1337  <t>
1338    <x:h>Note:</x:h> When automatically redirecting a POST request after
1339    receiving a 301 status code, some existing HTTP/1.0 user agents
1340    will erroneously change it into a GET request.
1341  </t>
1342</x:note>
1343</section>
1344
1345<section title="302 Found" anchor="status.302">
1346  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1347  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1348<t>
1349   The requested resource resides temporarily under a different URI.
1350   Since the redirection might be altered on occasion, the client &SHOULD;
1351   continue to use the request-target for future requests.  This response
1352   is only cacheable if indicated by a Cache-Control or Expires header
1353   field.
1354</t>
1355<t>
1356   The temporary URI &SHOULD; be given by the Location field in the
1357   response. Unless the request method was HEAD, the entity of the
1358   response &SHOULD; contain a short hypertext note with a hyperlink to
1359   the new URI(s).
1360</t>
1361<t>
1362   If the 302 status code is received in response to a request method
1363   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1364   then the request &MAY; be automatically redirected by the user agent without
1365   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1366   request unless it can be confirmed by the user, since this might
1367   change the conditions under which the request was issued.
1368</t>
1369<x:note>
1370  <t>
1371    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1372    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1373    specify that the client is not allowed to change the method on the
1374    redirected request.  However, most existing user agent implementations
1375    treat 302 as if it were a 303 response, performing a GET on the Location
1376    field-value regardless of the original request method. Therefore, a
1377    previous version of this specification
1378    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1379    status codes
1380    <xref target="status.303" format="none">303</xref> and
1381    <xref target="status.307" format="none">307</xref> for servers that wish
1382    to make unambiguously clear which kind of reaction is expected of the
1383    client.
1384  </t>
1385</x:note>
1386</section>
1387
1388<section title="303 See Other" anchor="status.303">
1389  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1390  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1391<t>
1392   The server directs the user agent to a different resource, indicated
1393   by a URI in the Location header field, that provides an indirect
1394   response to the original request.  The user agent &MAY; perform a GET
1395   request on the URI in the Location field in order to obtain a
1396   representation corresponding to the response, be redirected again,
1397   or end with an error status.  The Location URI is not a substitute
1398   reference for the originally requested resource.
1399</t>
1400<t>
1401   The 303 status is generally applicable to any HTTP method.  It is
1402   primarily used to allow the output of a POST action to redirect
1403   the user agent to a selected resource, since doing so provides the
1404   information corresponding to the POST response in a form that
1405   can be separately identified, bookmarked, and cached independent
1406   of the original request.
1407</t>
1408<t>
1409   A 303 response to a GET request indicates that the requested
1410   resource does not have a representation of its own that can be
1411   transferred by the server over HTTP.  The Location URI indicates a
1412   resource that is descriptive of the requested resource such that
1413   the follow-on representation may be useful without implying that
1414   it adequately represents the previously requested resource.
1415   Note that answers to the questions of what can be represented, what
1416   representations are adequate, and what might be a useful description
1417   are outside the scope of HTTP and thus entirely determined by the
1418   URI owner(s).
1419</t>
1420<t>
1421   A 303 response &SHOULD-NOT; be cached unless it is indicated as
1422   cacheable by Cache-Control or Expires header fields.  Except for
1423   responses to a HEAD request, the entity of a 303 response &SHOULD;
1424   contain a short hypertext note with a hyperlink to the Location URI.
1425</t>
1426</section>
1427
1428<section title="304 Not Modified" anchor="status.304">
1429  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1430  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1431<t>
1432   The response to the request has not been modified since the conditions
1433   indicated by the client's conditional GET request, as defined in &conditional;.
1434</t>
1435</section>
1436
1437<section title="305 Use Proxy" anchor="status.305">
1438  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1439  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1440<t>
1441   The 305 status was defined in a previous version of this specification
1442   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1443</t>
1444</section>
1445
1446<section title="306 (Unused)" anchor="status.306">
1447  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1448  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1449<t>
1450   The 306 status code was used in a previous version of the
1451   specification, is no longer used, and the code is reserved.
1452</t>
1453</section>
1454
1455<section title="307 Temporary Redirect" anchor="status.307">
1456  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1457  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1458<t>
1459   The requested resource resides temporarily under a different URI.
1460   Since the redirection &MAY; be altered on occasion, the client &SHOULD;
1461   continue to use the request-target for future requests.  This response
1462   is only cacheable if indicated by a Cache-Control or Expires header
1463   field.
1464</t>
1465<t>
1466   The temporary URI &SHOULD; be given by the Location field in the
1467   response. Unless the request method was HEAD, the entity of the
1468   response &SHOULD; contain a short hypertext note with a hyperlink to
1469   the new URI(s) , since many pre-HTTP/1.1 user agents do not
1470   understand the 307 status. Therefore, the note &SHOULD; contain the
1471   information necessary for a user to repeat the original request on
1472   the new URI.
1473</t>
1474<t>
1475   If the 307 status code is received in response to a request method
1476   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1477   then the request &MAY; be automatically redirected by the user agent without
1478   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1479   request unless it can be confirmed by the user, since this might
1480   change the conditions under which the request was issued.
1481</t>
1482</section>
1483</section>
1484
1485<section title="Client Error 4xx" anchor="status.4xx">
1486<t>
1487   The 4xx class of status code is intended for cases in which the
1488   client seems to have erred. Except when responding to a HEAD request,
1489   the server &SHOULD; include an entity containing an explanation of the
1490   error situation, and whether it is a temporary or permanent
1491   condition. These status codes are applicable to any request method.
1492   User agents &SHOULD; display any included entity to the user.
1493</t>
1494<t>
1495   If the client is sending data, a server implementation using TCP
1496   &SHOULD; be careful to ensure that the client acknowledges receipt of
1497   the packet(s) containing the response, before the server closes the
1498   input connection. If the client continues sending data to the server
1499   after the close, the server's TCP stack will send a reset packet to
1500   the client, which may erase the client's unacknowledged input buffers
1501   before they can be read and interpreted by the HTTP application.
1502</t>
1503
1504<section title="400 Bad Request" anchor="status.400">
1505  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1506  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1507<t>
1508   The request could not be understood by the server due to malformed
1509   syntax. The client &SHOULD-NOT;  repeat the request without
1510   modifications.
1511</t>
1512</section>
1513
1514<section title="401 Unauthorized" anchor="status.401">
1515  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1516  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1517<t>
1518   The request requires user authentication (see &auth;).
1519</t>
1520</section>
1521
1522<section title="402 Payment Required" anchor="status.402">
1523  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1524  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1525<t>
1526   This code is reserved for future use.
1527</t>
1528</section>
1529
1530<section title="403 Forbidden" anchor="status.403">
1531  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1532  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1533<t>
1534   The server understood the request, but is refusing to fulfill it.
1535   Authorization will not help and the request &SHOULD-NOT;  be repeated.
1536   If the request method was not HEAD and the server wishes to make
1537   public why the request has not been fulfilled, it &SHOULD; describe the
1538   reason for the refusal in the entity.  If the server does not wish to
1539   make this information available to the client, the status code 404
1540   (Not Found) can be used instead.
1541</t>
1542</section>
1543
1544<section title="404 Not Found" anchor="status.404">
1545  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1546  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1547<t>
1548   The server has not found anything matching the request-target. No
1549   indication is given of whether the condition is temporary or
1550   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1551   knows, through some internally configurable mechanism, that an old
1552   resource is permanently unavailable and has no forwarding address.
1553   This status code is commonly used when the server does not wish to
1554   reveal exactly why the request has been refused, or when no other
1555   response is applicable.
1556</t>
1557</section>
1558
1559<section title="405 Method Not Allowed" anchor="status.405">
1560  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1561  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1562<t>
1563   The method specified in the Request-Line is not allowed for the
1564   resource identified by the request-target. The response &MUST; include an
1565   Allow header containing a list of valid methods for the requested
1566   resource.
1567</t>
1568</section>
1569
1570<section title="406 Not Acceptable" anchor="status.406">
1571  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1572  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1573<t>
1574   The resource identified by the request is only capable of generating
1575   response entities which have content characteristics not acceptable
1576   according to the accept headers sent in the request.
1577</t>
1578<t>
1579   Unless it was a HEAD request, the response &SHOULD; include an entity
1580   containing a list of available entity characteristics and location(s)
1581   from which the user or user agent can choose the one most
1582   appropriate. The entity format is specified by the media type given
1583   in the Content-Type header field. Depending upon the format and the
1584   capabilities of the user agent, selection of the most appropriate
1585   choice &MAY; be performed automatically. However, this specification
1586   does not define any standard for such automatic selection.
1587</t>
1588<x:note>
1589  <t>
1590    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1591    not acceptable according to the accept headers sent in the
1592    request. In some cases, this may even be preferable to sending a
1593    406 response. User agents are encouraged to inspect the headers of
1594    an incoming response to determine if it is acceptable.
1595  </t>
1596</x:note>
1597<t>
1598   If the response could be unacceptable, a user agent &SHOULD;
1599   temporarily stop receipt of more data and query the user for a
1600   decision on further actions.
1601</t>
1602</section>
1603
1604<section title="407 Proxy Authentication Required" anchor="status.407">
1605  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1606  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1607<t>
1608   This code is similar to 401 (Unauthorized), but indicates that the
1609   client must first authenticate itself with the proxy (see &auth;).
1610</t>
1611</section>
1612
1613<section title="408 Request Timeout" anchor="status.408">
1614  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1615  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1616<t>
1617   The client did not produce a request within the time that the server
1618   was prepared to wait. The client &MAY; repeat the request without
1619   modifications at any later time.
1620</t>
1621</section>
1622
1623<section title="409 Conflict" anchor="status.409">
1624  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1625  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1626<t>
1627   The request could not be completed due to a conflict with the current
1628   state of the resource. This code is only allowed in situations where
1629   it is expected that the user might be able to resolve the conflict
1630   and resubmit the request. The response body &SHOULD; include enough
1631   information for the user to recognize the source of the conflict.
1632   Ideally, the response entity would include enough information for the
1633   user or user agent to fix the problem; however, that might not be
1634   possible and is not required.
1635</t>
1636<t>
1637   Conflicts are most likely to occur in response to a PUT request. For
1638   example, if versioning were being used and the entity being PUT
1639   included changes to a resource which conflict with those made by an
1640   earlier (third-party) request, the server might use the 409 response
1641   to indicate that it can't complete the request. In this case, the
1642   response entity would likely contain a list of the differences
1643   between the two versions in a format defined by the response
1644   Content-Type.
1645</t>
1646</section>
1647
1648<section title="410 Gone" anchor="status.410">
1649  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1650  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1651<t>
1652   The requested resource is no longer available at the server and no
1653   forwarding address is known. This condition is expected to be
1654   considered permanent. Clients with link editing capabilities &SHOULD;
1655   delete references to the request-target after user approval. If the
1656   server does not know, or has no facility to determine, whether or not
1657   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1658   used instead. This response is cacheable unless indicated otherwise.
1659</t>
1660<t>
1661   The 410 response is primarily intended to assist the task of web
1662   maintenance by notifying the recipient that the resource is
1663   intentionally unavailable and that the server owners desire that
1664   remote links to that resource be removed. Such an event is common for
1665   limited-time, promotional services and for resources belonging to
1666   individuals no longer working at the server's site. It is not
1667   necessary to mark all permanently unavailable resources as "gone" or
1668   to keep the mark for any length of time -- that is left to the
1669   discretion of the server owner.
1670</t>
1671</section>
1672
1673<section title="411 Length Required" anchor="status.411">
1674  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1675  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1676<t>
1677   The server refuses to accept the request without a defined Content-Length.
1678   The client &MAY; repeat the request if it adds a valid
1679   Content-Length header field containing the length of the message-body
1680   in the request message.
1681</t>
1682</section>
1683
1684<section title="412 Precondition Failed" anchor="status.412">
1685  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1686  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1687<t>
1688   The precondition given in one or more of the request-header fields
1689   evaluated to false when it was tested on the server, as defined in
1690   &conditional;.
1691</t>
1692</section>
1693
1694<section title="413 Request Entity Too Large" anchor="status.413">
1695  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1696  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1697<t>
1698   The server is refusing to process a request because the request
1699   entity is larger than the server is willing or able to process. The
1700   server &MAY; close the connection to prevent the client from continuing
1701   the request.
1702</t>
1703<t>
1704   If the condition is temporary, the server &SHOULD; include a Retry-After
1705   header field to indicate that it is temporary and after what
1706   time the client &MAY; try again.
1707</t>
1708</section>
1709
1710<section title="414 URI Too Long" anchor="status.414">
1711  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1712  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1713<t>
1714   The server is refusing to service the request because the request-target
1715   is longer than the server is willing to interpret. This rare
1716   condition is only likely to occur when a client has improperly
1717   converted a POST request to a GET request with long query
1718   information, when the client has descended into a URI "black hole" of
1719   redirection (e.g., a redirected URI prefix that points to a suffix of
1720   itself), or when the server is under attack by a client attempting to
1721   exploit security holes present in some servers using fixed-length
1722   buffers for reading or manipulating the request-target.
1723</t>
1724</section>
1725
1726<section title="415 Unsupported Media Type" anchor="status.415">
1727  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1728  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1729<t>
1730   The server is refusing to service the request because the entity of
1731   the request is in a format not supported by the requested resource
1732   for the requested method.
1733</t>
1734</section>
1735
1736<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1737  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1738  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1739<t>
1740   The request included a Range request-header field (&header-range;) and none of
1741   the range-specifier values in this field overlap the current extent
1742   of the selected resource.
1743</t>
1744</section>
1745
1746<section title="417 Expectation Failed" anchor="status.417">
1747  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
1748  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
1749<t>
1750   The expectation given in an Expect request-header field (see <xref target="header.expect"/>)
1751   could not be met by this server, or, if the server is a proxy,
1752   the server has unambiguous evidence that the request could not be met
1753   by the next-hop server.
1754</t>
1755</section>
1756</section>
1757
1758<section title="Server Error 5xx" anchor="status.5xx">
1759<t>
1760   Response status codes beginning with the digit "5" indicate cases in
1761   which the server is aware that it has erred or is incapable of
1762   performing the request. Except when responding to a HEAD request, the
1763   server &SHOULD; include an entity containing an explanation of the
1764   error situation, and whether it is a temporary or permanent
1765   condition. User agents &SHOULD; display any included entity to the
1766   user. These response codes are applicable to any request method.
1767</t>
1768
1769<section title="500 Internal Server Error" anchor="status.500">
1770  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
1771  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
1772<t>
1773   The server encountered an unexpected condition which prevented it
1774   from fulfilling the request.
1775</t>
1776</section>
1777
1778<section title="501 Not Implemented" anchor="status.501">
1779  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
1780  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
1781<t>
1782   The server does not support the functionality required to fulfill the
1783   request. This is the appropriate response when the server does not
1784   recognize the request method and is not capable of supporting it for
1785   any resource.
1786</t>
1787</section>
1788
1789<section title="502 Bad Gateway" anchor="status.502">
1790  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
1791  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
1792<t>
1793   The server, while acting as a gateway or proxy, received an invalid
1794   response from the upstream server it accessed in attempting to
1795   fulfill the request.
1796</t>
1797</section>
1798
1799<section title="503 Service Unavailable" anchor="status.503">
1800  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
1801  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
1802<t>
1803   The server is currently unable to handle the request due to a
1804   temporary overloading or maintenance of the server. The implication
1805   is that this is a temporary condition which will be alleviated after
1806   some delay. If known, the length of the delay &MAY; be indicated in a
1807   Retry-After header. If no Retry-After is given, the client &SHOULD;
1808   handle the response as it would for a 500 response.
1809</t>
1810<x:note>
1811  <t>
1812    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
1813    server must use it when becoming overloaded. Some servers may wish
1814    to simply refuse the connection.
1815  </t>
1816</x:note>
1817</section>
1818
1819<section title="504 Gateway Timeout" anchor="status.504">
1820  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
1821  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
1822<t>
1823   The server, while acting as a gateway or proxy, did not receive a
1824   timely response from the upstream server specified by the URI (e.g.
1825   HTTP, FTP, LDAP) or some other auxiliary server (e.g. DNS) it needed
1826   to access in attempting to complete the request.
1827</t>
1828<x:note>
1829  <t>
1830    <x:h>Note:</x:h> Note to implementors: some deployed proxies are known to
1831    return 400 or 500 when DNS lookups time out.
1832  </t>
1833</x:note>
1834</section>
1835
1836<section title="505 HTTP Version Not Supported" anchor="status.505">
1837  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
1838  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
1839<t>
1840   The server does not support, or refuses to support, the protocol
1841   version that was used in the request message. The server is
1842   indicating that it is unable or unwilling to complete the request
1843   using the same major version as the client, as described in &http-version;,
1844   other than with this error message. The response &SHOULD; contain
1845   an entity describing why that version is not supported and what other
1846   protocols are supported by that server.
1847</t>
1848
1849</section>
1850</section>
1851</section>
1852
1853
1854<section title="Header Field Definitions" anchor="header.fields">
1855<t>
1856   This section defines the syntax and semantics of HTTP/1.1 header fields
1857   related to request and response semantics.
1858</t>
1859<t>
1860   For entity-header fields, both sender and recipient refer to either the
1861   client or the server, depending on who sends and who receives the entity.
1862</t>
1863
1864<section title="Allow" anchor="header.allow">
1865  <iref primary="true" item="Allow header" x:for-anchor=""/>
1866  <iref primary="true" item="Headers" subitem="Allow" x:for-anchor=""/>
1867  <x:anchor-alias value="Allow"/>
1868  <x:anchor-alias value="Allow-v"/>
1869<t>
1870      The response-header field "Allow" lists the set of methods advertised as
1871      supported by the resource identified by the request-target. The purpose of
1872      this field is strictly to inform the recipient of valid methods
1873      associated with the resource. An Allow header field &MUST; be
1874      present in a 405 (Method Not Allowed) response.
1875</t>
1876<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/><iref primary="true" item="Grammar" subitem="Allow-v"/>
1877  <x:ref>Allow</x:ref>   = "Allow" ":" <x:ref>OWS</x:ref> <x:ref>Allow-v</x:ref>
1878  <x:ref>Allow-v</x:ref> = #<x:ref>Method</x:ref>
1879</artwork></figure>
1880<t>
1881      Example of use:
1882</t>
1883<figure><artwork type="example">
1884  Allow: GET, HEAD, PUT
1885</artwork></figure>
1886<t>
1887      The actual set of allowed methods is defined
1888      by the origin server at the time of each request.
1889</t>
1890<t>
1891      A proxy &MUST-NOT; modify the Allow header field even if it does not
1892      understand all the methods specified, since the user agent might
1893      have other means of communicating with the origin server.
1894</t>
1895</section>
1896
1897<section title="Expect" anchor="header.expect">
1898  <iref primary="true" item="Expect header" x:for-anchor=""/>
1899  <iref primary="true" item="Headers" subitem="Expect" x:for-anchor=""/>
1900  <x:anchor-alias value="Expect"/>
1901  <x:anchor-alias value="Expect-v"/>
1902  <x:anchor-alias value="expectation"/>
1903  <x:anchor-alias value="expectation-extension"/>
1904  <x:anchor-alias value="expect-params"/>
1905<t>
1906   The request-header field "Expect" is used to indicate that particular
1907   server behaviors are required by the client.
1908</t>
1909<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"/>
1910  <x:ref>Expect</x:ref>       = "Expect" ":" <x:ref>OWS</x:ref> <x:ref>Expect-v</x:ref>
1911  <x:ref>Expect-v</x:ref>     = 1#<x:ref>expectation</x:ref>
1912 
1913  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
1914  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
1915                           *<x:ref>expect-params</x:ref> ]
1916  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
1917</artwork></figure>
1918<t>
1919   A server that does not understand or is unable to comply with any of
1920   the expectation values in the Expect field of a request &MUST; respond
1921   with appropriate error status. The server &MUST; respond with a 417
1922   (Expectation Failed) status if any of the expectations cannot be met
1923   or, if there are other problems with the request, some other 4xx
1924   status.
1925</t>
1926<t>
1927   This header field is defined with extensible syntax to allow for
1928   future extensions. If a server receives a request containing an
1929   Expect field that includes an expectation-extension that it does not
1930   support, it &MUST; respond with a 417 (Expectation Failed) status.
1931</t>
1932<t>
1933   Comparison of expectation values is case-insensitive for unquoted
1934   tokens (including the 100-continue token), and is case-sensitive for
1935   quoted-string expectation-extensions.
1936</t>
1937<t>
1938   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
1939   return a 417 (Expectation Failed) status if it receives a request
1940   with an expectation that it cannot meet. However, the Expect
1941   request-header itself is end-to-end; it &MUST; be forwarded if the
1942   request is forwarded.
1943</t>
1944<t>
1945   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
1946   Expect header.
1947</t>
1948<t>
1949   See &use100; for the use of the 100 (Continue) status.
1950</t>
1951</section>
1952
1953<section title="From" anchor="header.from">
1954  <iref primary="true" item="From header" x:for-anchor=""/>
1955  <iref primary="true" item="Headers" subitem="From" x:for-anchor=""/>
1956  <x:anchor-alias value="From"/>
1957  <x:anchor-alias value="From-v"/>
1958  <x:anchor-alias value="mailbox"/>
1959<t>
1960   The request-header field "From", if given, &SHOULD; contain an Internet
1961   e-mail address for the human user who controls the requesting user
1962   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
1963   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
1964</t>
1965<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/><iref primary="true" item="Grammar" subitem="From-v"/>
1966  <x:ref>From</x:ref>    = "From" ":" <x:ref>OWS</x:ref> <x:ref>From-v</x:ref>
1967  <x:ref>From-v</x:ref>  = <x:ref>mailbox</x:ref>
1968 
1969  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
1970</artwork></figure>
1971<t>
1972   An example is:
1973</t>
1974<figure><artwork type="example">
1975  From: webmaster@example.org
1976</artwork></figure>
1977<t>
1978   This header field &MAY; be used for logging purposes and as a means for
1979   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
1980   be used as an insecure form of access protection. The interpretation
1981   of this field is that the request is being performed on behalf of the
1982   person given, who accepts responsibility for the method performed. In
1983   particular, robot agents &SHOULD; include this header so that the
1984   person responsible for running the robot can be contacted if problems
1985   occur on the receiving end.
1986</t>
1987<t>
1988   The Internet e-mail address in this field &MAY; be separate from the
1989   Internet host which issued the request. For example, when a request
1990   is passed through a proxy the original issuer's address &SHOULD; be
1991   used.
1992</t>
1993<t>
1994   The client &SHOULD-NOT;  send the From header field without the user's
1995   approval, as it might conflict with the user's privacy interests or
1996   their site's security policy. It is strongly recommended that the
1997   user be able to disable, enable, and modify the value of this field
1998   at any time prior to a request.
1999</t>
2000</section>
2001
2002<section title="Location" anchor="header.location">
2003  <iref primary="true" item="Location header" x:for-anchor=""/>
2004  <iref primary="true" item="Headers" subitem="Location" x:for-anchor=""/>
2005  <x:anchor-alias value="Location"/>
2006  <x:anchor-alias value="Location-v"/>
2007<t>
2008   The response-header field "Location" is used for the identification of a
2009   new resource or to redirect the recipient to a location other than the
2010   request-target for completion of the request.  For 201 (Created)
2011   responses, the Location is that of the new resource which was created
2012   by the request. For 3xx responses, the location &SHOULD; indicate the
2013   server's preferred URI for automatic redirection to the resource. The
2014   field value consists of a single URI.
2015</t>
2016<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/><iref primary="true" item="Grammar" subitem="Location-v"/>
2017  <x:ref>Location</x:ref>       = "Location" ":" <x:ref>OWS</x:ref> <x:ref>Location-v</x:ref>
2018  <x:ref>Location-v</x:ref>     = <x:ref>URI</x:ref>
2019</artwork></figure>
2020<t>
2021   An example is:
2022</t>
2023<figure><artwork type="example">
2024  Location: http://www.example.org/pub/WWW/People.html
2025</artwork></figure>
2026<t>
2027   There are circumstances in which a fragment identifier in a Location URI would not be appropriate:
2028   <list style="symbols">
2029      <t>With a 201 Created response, because in this usage the Location header specifies the URI for the entire created resource.</t>
2030      <t>With 305 Use Proxy.</t>
2031   </list>
2032</t>
2033<x:note>
2034  <t>
2035    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2036    from Location in that the Content-Location identifies the original
2037    location of the entity enclosed in the response. It is therefore
2038    possible for a response to contain header fields for both Location
2039    and Content-Location.
2040  </t>
2041</x:note>
2042</section>
2043
2044<section title="Max-Forwards" anchor="header.max-forwards">
2045  <iref primary="true" item="Max-Forwards header" x:for-anchor=""/>
2046  <iref primary="true" item="Headers" subitem="Max-Forwards" x:for-anchor=""/>
2047  <x:anchor-alias value="Max-Forwards"/>
2048  <x:anchor-alias value="Max-Forwards-v"/>
2049<t>
2050   The request-header "Max-Forwards" field provides a mechanism with the
2051   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>) methods to limit the
2052   number of proxies or gateways that can forward the request to the
2053   next inbound server. This can be useful when the client is attempting
2054   to trace a request chain which appears to be failing or looping in
2055   mid-chain.
2056</t>
2057<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/><iref primary="true" item="Grammar" subitem="Max-Forwards-v"/>
2058  <x:ref>Max-Forwards</x:ref>   = "Max-Forwards" ":" <x:ref>OWS</x:ref> <x:ref>Max-Forwards-v</x:ref>
2059  <x:ref>Max-Forwards-v</x:ref> = 1*<x:ref>DIGIT</x:ref>
2060</artwork></figure>
2061<t>
2062   The Max-Forwards value is a decimal integer indicating the remaining
2063   number of times this request message may be forwarded.
2064</t>
2065<t>
2066   Each proxy or gateway recipient of a TRACE or OPTIONS request
2067   containing a Max-Forwards header field &MUST; check and update its
2068   value prior to forwarding the request. If the received value is zero
2069   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2070   respond as the final recipient. If the received Max-Forwards value is
2071   greater than zero, then the forwarded message &MUST; contain an updated
2072   Max-Forwards field with a value decremented by one (1).
2073</t>
2074<t>
2075   The Max-Forwards header field &MAY; be ignored for all other methods
2076   defined by this specification and for any extension methods for which
2077   it is not explicitly referred to as part of that method definition.
2078</t>
2079</section>
2080
2081<section title="Referer" anchor="header.referer">
2082  <iref primary="true" item="Referer header" x:for-anchor=""/>
2083  <iref primary="true" item="Headers" subitem="Referer" x:for-anchor=""/>
2084  <x:anchor-alias value="Referer"/>
2085  <x:anchor-alias value="Referer-v"/>
2086<t>
2087   The request-header field "Referer" [sic] allows the client to specify, for
2088   the server's benefit, the address (URI) of the resource from which the
2089   request-target was obtained (the "referrer", although the header field is
2090   misspelled.).
2091</t>
2092<t>
2093   The Referer header allows servers to generate lists of back-links to
2094   resources for interest, logging, optimized caching, etc. It also allows
2095   obsolete or mistyped links to be traced for maintenance. Some servers use
2096   Referer as a means of controlling where they allow links from (so-called
2097   "deep linking"), but it should be noted that legitimate requests are not
2098   required to contain a Referer header field.
2099</t>
2100<t>
2101   If the request-target was obtained from a source that does not have its own
2102   URI (e.g., input from the user keyboard), the Referer field MUST either be
2103   sent with the value "about:blank", or not be sent at all. Note that this
2104   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2105</t>
2106<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/><iref primary="true" item="Grammar" subitem="Referer-v"/>
2107  <x:ref>Referer</x:ref>        = "Referer" ":" <x:ref>OWS</x:ref> <x:ref>Referer-v</x:ref>
2108  <x:ref>Referer-v</x:ref>      = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2109</artwork></figure>
2110<t>
2111   Example:
2112</t>
2113<figure><artwork type="example">
2114  Referer: http://www.example.org/hypertext/Overview.html
2115</artwork></figure>
2116<t>
2117   If the field value is a relative URI, it &SHOULD; be interpreted
2118   relative to the request-target. The URI &MUST-NOT; include a fragment. See
2119   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2120</t>
2121</section>
2122
2123<section title="Retry-After" anchor="header.retry-after">
2124  <iref primary="true" item="Retry-After header" x:for-anchor=""/>
2125  <iref primary="true" item="Headers" subitem="Retry-After" x:for-anchor=""/>
2126  <x:anchor-alias value="Retry-After"/>
2127  <x:anchor-alias value="Retry-After-v"/>
2128<t>
2129   The response-header "Retry-After" field can be used with a 503 (Service
2130   Unavailable) response to indicate how long the service is expected to
2131   be unavailable to the requesting client. This field &MAY; also be used
2132   with any 3xx (Redirection) response to indicate the minimum time the
2133   user-agent is asked wait before issuing the redirected request. The
2134   value of this field can be either an HTTP-date or an integer number
2135   of seconds (in decimal) after the time of the response.
2136</t>
2137<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/><iref primary="true" item="Grammar" subitem="Retry-After-v"/>
2138  <x:ref>Retry-After</x:ref>   = "Retry-After" ":" <x:ref>OWS</x:ref> <x:ref>Retry-After-v</x:ref>
2139  <x:ref>Retry-After-v</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2140</artwork></figure>
2141<t anchor="rule.delta-seconds">
2142  <x:anchor-alias value="delta-seconds"/>
2143   Time spans are non-negative decimal integers, representing time in
2144   seconds.
2145</t>
2146<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2147  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2148</artwork></figure>
2149<t>
2150   Two examples of its use are
2151</t>
2152<figure><artwork type="example">
2153  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2154  Retry-After: 120
2155</artwork></figure>
2156<t>
2157   In the latter example, the delay is 2 minutes.
2158</t>
2159</section>
2160
2161<section title="Server" anchor="header.server">
2162  <iref primary="true" item="Server header" x:for-anchor=""/>
2163  <iref primary="true" item="Headers" subitem="Server" x:for-anchor=""/>
2164  <x:anchor-alias value="Server"/>
2165  <x:anchor-alias value="Server-v"/>
2166<t>
2167   The response-header field "Server" contains information about the
2168   software used by the origin server to handle the request. The field
2169   can contain multiple product tokens (&product-tokens;) and comments
2170   identifying the server and any significant subproducts. The product
2171   tokens are listed in order of their significance for identifying the
2172   application.
2173</t>
2174<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/><iref primary="true" item="Grammar" subitem="Server-v"/>
2175  <x:ref>Server</x:ref>         = "Server" ":" <x:ref>OWS</x:ref> <x:ref>Server-v</x:ref>
2176  <x:ref>Server-v</x:ref>       = <x:ref>product</x:ref>
2177                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2178</artwork></figure>
2179<t>
2180   Example:
2181</t>
2182<figure><artwork type="example">
2183  Server: CERN/3.0 libwww/2.17
2184</artwork></figure>
2185<t>
2186   If the response is being forwarded through a proxy, the proxy
2187   application &MUST-NOT; modify the Server response-header. Instead, it
2188   &MUST; include a Via field (as described in &header-via;).
2189</t>
2190<x:note>
2191  <t>
2192    <x:h>Note:</x:h> Revealing the specific software version of the server might
2193    allow the server machine to become more vulnerable to attacks
2194    against software that is known to contain security holes. Server
2195    implementors are encouraged to make this field a configurable
2196    option.
2197  </t>
2198</x:note>
2199</section>
2200
2201<section title="User-Agent" anchor="header.user-agent">
2202  <iref primary="true" item="User-Agent header" x:for-anchor=""/>
2203  <iref primary="true" item="Headers" subitem="User-Agent" x:for-anchor=""/>
2204  <x:anchor-alias value="User-Agent"/>
2205  <x:anchor-alias value="User-Agent-v"/>
2206<t>
2207   The request-header field "User-Agent" contains information about the
2208   user agent originating the request. This is for statistical purposes,
2209   the tracing of protocol violations, and automated recognition of user
2210   agents for the sake of tailoring responses to avoid particular user
2211   agent limitations. User agents &SHOULD; include this field with
2212   requests. The field can contain multiple product tokens (&product-tokens;)
2213   and comments identifying the agent and any subproducts which form a
2214   significant part of the user agent. By convention, the product tokens
2215   are listed in order of their significance for identifying the
2216   application.
2217</t>
2218<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/><iref primary="true" item="Grammar" subitem="User-Agent-v"/>
2219  <x:ref>User-Agent</x:ref>     = "User-Agent" ":" <x:ref>OWS</x:ref> <x:ref>User-Agent-v</x:ref>
2220  <x:ref>User-Agent-v</x:ref>   = <x:ref>product</x:ref>
2221                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2222</artwork></figure>
2223<t>
2224   Example:
2225</t>
2226<figure><artwork type="example">
2227  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2228</artwork></figure>
2229</section>
2230
2231</section>
2232
2233<section title="IANA Considerations" anchor="IANA.considerations">
2234
2235<section title="Method Registry" anchor="method.registration">
2236<t>
2237  The registration procedure for HTTP Methods is defined by
2238  <xref target="method.registry"/> of this document.
2239</t>
2240<t>
2241   The HTTP Method Registry located at <eref target="http://www.iana.org/assignments/http-methods"/>
2242   should be populated with the registrations below:
2243</t>
2244<?BEGININC p2-semantics.iana-methods ?>
2245<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2246<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2247   <ttcol>Method</ttcol>
2248   <ttcol>Safe</ttcol>
2249   <ttcol>Reference</ttcol>
2250   <c>CONNECT</c>
2251   <c>no</c>
2252   <c>
2253      <xref target="CONNECT"/>
2254   </c>
2255   <c>DELETE</c>
2256   <c>no</c>
2257   <c>
2258      <xref target="DELETE"/>
2259   </c>
2260   <c>GET</c>
2261   <c>yes</c>
2262   <c>
2263      <xref target="GET"/>
2264   </c>
2265   <c>HEAD</c>
2266   <c>yes</c>
2267   <c>
2268      <xref target="HEAD"/>
2269   </c>
2270   <c>OPTIONS</c>
2271   <c>yes</c>
2272   <c>
2273      <xref target="OPTIONS"/>
2274   </c>
2275   <c>POST</c>
2276   <c>no</c>
2277   <c>
2278      <xref target="POST"/>
2279   </c>
2280   <c>PUT</c>
2281   <c>no</c>
2282   <c>
2283      <xref target="PUT"/>
2284   </c>
2285   <c>TRACE</c>
2286   <c>yes</c>
2287   <c>
2288      <xref target="TRACE"/>
2289   </c>
2290</texttable>
2291<!--(END)-->
2292<?ENDINC p2-semantics.iana-methods ?>
2293</section>
2294
2295<section title="Status Code Registry" anchor="status.code.registration">
2296<t>
2297   The registration procedure for HTTP Status Codes -- previously defined
2298   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> -- is now defined
2299   by <xref target="status.code.registry"/> of this document.
2300</t>
2301<t>
2302   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2303   should be updated with the registrations below:
2304</t>
2305<?BEGININC p2-semantics.iana-status-codes ?>
2306<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2307<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2308   <ttcol>Value</ttcol>
2309   <ttcol>Description</ttcol>
2310   <ttcol>Reference</ttcol>
2311   <c>100</c>
2312   <c>Continue</c>
2313   <c>
2314      <xref target="status.100"/>
2315   </c>
2316   <c>101</c>
2317   <c>Switching Protocols</c>
2318   <c>
2319      <xref target="status.101"/>
2320   </c>
2321   <c>200</c>
2322   <c>OK</c>
2323   <c>
2324      <xref target="status.200"/>
2325   </c>
2326   <c>201</c>
2327   <c>Created</c>
2328   <c>
2329      <xref target="status.201"/>
2330   </c>
2331   <c>202</c>
2332   <c>Accepted</c>
2333   <c>
2334      <xref target="status.202"/>
2335   </c>
2336   <c>203</c>
2337   <c>Non-Authoritative Information</c>
2338   <c>
2339      <xref target="status.203"/>
2340   </c>
2341   <c>204</c>
2342   <c>No Content</c>
2343   <c>
2344      <xref target="status.204"/>
2345   </c>
2346   <c>205</c>
2347   <c>Reset Content</c>
2348   <c>
2349      <xref target="status.205"/>
2350   </c>
2351   <c>206</c>
2352   <c>Partial Content</c>
2353   <c>
2354      <xref target="status.206"/>
2355   </c>
2356   <c>300</c>
2357   <c>Multiple Choices</c>
2358   <c>
2359      <xref target="status.300"/>
2360   </c>
2361   <c>301</c>
2362   <c>Moved Permanently</c>
2363   <c>
2364      <xref target="status.301"/>
2365   </c>
2366   <c>302</c>
2367   <c>Found</c>
2368   <c>
2369      <xref target="status.302"/>
2370   </c>
2371   <c>303</c>
2372   <c>See Other</c>
2373   <c>
2374      <xref target="status.303"/>
2375   </c>
2376   <c>304</c>
2377   <c>Not Modified</c>
2378   <c>
2379      <xref target="status.304"/>
2380   </c>
2381   <c>305</c>
2382   <c>Use Proxy</c>
2383   <c>
2384      <xref target="status.305"/>
2385   </c>
2386   <c>306</c>
2387   <c>(Unused)</c>
2388   <c>
2389      <xref target="status.306"/>
2390   </c>
2391   <c>307</c>
2392   <c>Temporary Redirect</c>
2393   <c>
2394      <xref target="status.307"/>
2395   </c>
2396   <c>400</c>
2397   <c>Bad Request</c>
2398   <c>
2399      <xref target="status.400"/>
2400   </c>
2401   <c>401</c>
2402   <c>Unauthorized</c>
2403   <c>
2404      <xref target="status.401"/>
2405   </c>
2406   <c>402</c>
2407   <c>Payment Required</c>
2408   <c>
2409      <xref target="status.402"/>
2410   </c>
2411   <c>403</c>
2412   <c>Forbidden</c>
2413   <c>
2414      <xref target="status.403"/>
2415   </c>
2416   <c>404</c>
2417   <c>Not Found</c>
2418   <c>
2419      <xref target="status.404"/>
2420   </c>
2421   <c>405</c>
2422   <c>Method Not Allowed</c>
2423   <c>
2424      <xref target="status.405"/>
2425   </c>
2426   <c>406</c>
2427   <c>Not Acceptable</c>
2428   <c>
2429      <xref target="status.406"/>
2430   </c>
2431   <c>407</c>
2432   <c>Proxy Authentication Required</c>
2433   <c>
2434      <xref target="status.407"/>
2435   </c>
2436   <c>408</c>
2437   <c>Request Timeout</c>
2438   <c>
2439      <xref target="status.408"/>
2440   </c>
2441   <c>409</c>
2442   <c>Conflict</c>
2443   <c>
2444      <xref target="status.409"/>
2445   </c>
2446   <c>410</c>
2447   <c>Gone</c>
2448   <c>
2449      <xref target="status.410"/>
2450   </c>
2451   <c>411</c>
2452   <c>Length Required</c>
2453   <c>
2454      <xref target="status.411"/>
2455   </c>
2456   <c>412</c>
2457   <c>Precondition Failed</c>
2458   <c>
2459      <xref target="status.412"/>
2460   </c>
2461   <c>413</c>
2462   <c>Request Entity Too Large</c>
2463   <c>
2464      <xref target="status.413"/>
2465   </c>
2466   <c>414</c>
2467   <c>URI Too Long</c>
2468   <c>
2469      <xref target="status.414"/>
2470   </c>
2471   <c>415</c>
2472   <c>Unsupported Media Type</c>
2473   <c>
2474      <xref target="status.415"/>
2475   </c>
2476   <c>416</c>
2477   <c>Requested Range Not Satisfiable</c>
2478   <c>
2479      <xref target="status.416"/>
2480   </c>
2481   <c>417</c>
2482   <c>Expectation Failed</c>
2483   <c>
2484      <xref target="status.417"/>
2485   </c>
2486   <c>500</c>
2487   <c>Internal Server Error</c>
2488   <c>
2489      <xref target="status.500"/>
2490   </c>
2491   <c>501</c>
2492   <c>Not Implemented</c>
2493   <c>
2494      <xref target="status.501"/>
2495   </c>
2496   <c>502</c>
2497   <c>Bad Gateway</c>
2498   <c>
2499      <xref target="status.502"/>
2500   </c>
2501   <c>503</c>
2502   <c>Service Unavailable</c>
2503   <c>
2504      <xref target="status.503"/>
2505   </c>
2506   <c>504</c>
2507   <c>Gateway Timeout</c>
2508   <c>
2509      <xref target="status.504"/>
2510   </c>
2511   <c>505</c>
2512   <c>HTTP Version Not Supported</c>
2513   <c>
2514      <xref target="status.505"/>
2515   </c>
2516</texttable>
2517<!--(END)-->
2518<?ENDINC p2-semantics.iana-status-codes ?>
2519</section>
2520<section title="Message Header Registration" anchor="message.header.registration">
2521<t>
2522   The Message Header Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> should be updated
2523   with the permanent registrations below (see <xref target="RFC3864"/>):
2524</t>
2525<?BEGININC p2-semantics.iana-headers ?>
2526<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2527<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2528   <ttcol>Header Field Name</ttcol>
2529   <ttcol>Protocol</ttcol>
2530   <ttcol>Status</ttcol>
2531   <ttcol>Reference</ttcol>
2532
2533   <c>Allow</c>
2534   <c>http</c>
2535   <c>standard</c>
2536   <c>
2537      <xref target="header.allow"/>
2538   </c>
2539   <c>Expect</c>
2540   <c>http</c>
2541   <c>standard</c>
2542   <c>
2543      <xref target="header.expect"/>
2544   </c>
2545   <c>From</c>
2546   <c>http</c>
2547   <c>standard</c>
2548   <c>
2549      <xref target="header.from"/>
2550   </c>
2551   <c>Location</c>
2552   <c>http</c>
2553   <c>standard</c>
2554   <c>
2555      <xref target="header.location"/>
2556   </c>
2557   <c>Max-Forwards</c>
2558   <c>http</c>
2559   <c>standard</c>
2560   <c>
2561      <xref target="header.max-forwards"/>
2562   </c>
2563   <c>Referer</c>
2564   <c>http</c>
2565   <c>standard</c>
2566   <c>
2567      <xref target="header.referer"/>
2568   </c>
2569   <c>Retry-After</c>
2570   <c>http</c>
2571   <c>standard</c>
2572   <c>
2573      <xref target="header.retry-after"/>
2574   </c>
2575   <c>Server</c>
2576   <c>http</c>
2577   <c>standard</c>
2578   <c>
2579      <xref target="header.server"/>
2580   </c>
2581   <c>User-Agent</c>
2582   <c>http</c>
2583   <c>standard</c>
2584   <c>
2585      <xref target="header.user-agent"/>
2586   </c>
2587</texttable>
2588<!--(END)-->
2589<?ENDINC p2-semantics.iana-headers ?>
2590<t>
2591   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2592</t>
2593</section>
2594</section>
2595
2596<section title="Security Considerations" anchor="security.considerations">
2597<t>
2598   This section is meant to inform application developers, information
2599   providers, and users of the security limitations in HTTP/1.1 as
2600   described by this document. The discussion does not include
2601   definitive solutions to the problems revealed, though it does make
2602   some suggestions for reducing security risks.
2603</t>
2604
2605<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2606<t>
2607   Like any generic data transfer protocol, HTTP cannot regulate the
2608   content of the data that is transferred, nor is there any a priori
2609   method of determining the sensitivity of any particular piece of
2610   information within the context of any given request. Therefore,
2611   applications &SHOULD; supply as much control over this information as
2612   possible to the provider of that information. Four header fields are
2613   worth special mention in this context: Server, Via, Referer and From.
2614</t>
2615<t>
2616   Revealing the specific software version of the server might allow the
2617   server machine to become more vulnerable to attacks against software
2618   that is known to contain security holes. Implementors &SHOULD; make the
2619   Server header field a configurable option.
2620</t>
2621<t>
2622   Proxies which serve as a portal through a network firewall &SHOULD;
2623   take special precautions regarding the transfer of header information
2624   that identifies the hosts behind the firewall. In particular, they
2625   &SHOULD; remove, or replace with sanitized versions, any Via fields
2626   generated behind the firewall.
2627</t>
2628<t>
2629   The Referer header allows reading patterns to be studied and reverse
2630   links drawn. Although it can be very useful, its power can be abused
2631   if user details are not separated from the information contained in
2632   the Referer. Even when the personal information has been removed, the
2633   Referer header might indicate a private document's URI whose
2634   publication would be inappropriate.
2635</t>
2636<t>
2637   The information sent in the From field might conflict with the user's
2638   privacy interests or their site's security policy, and hence it
2639   &SHOULD-NOT;  be transmitted without the user being able to disable,
2640   enable, and modify the contents of the field. The user &MUST; be able
2641   to set the contents of this field within a user preference or
2642   application defaults configuration.
2643</t>
2644<t>
2645   We suggest, though do not require, that a convenient toggle interface
2646   be provided for the user to enable or disable the sending of From and
2647   Referer information.
2648</t>
2649<t>
2650   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref target="header.server"/>) header
2651   fields can sometimes be used to determine that a specific client or
2652   server have a particular security hole which might be exploited.
2653   Unfortunately, this same information is often used for other valuable
2654   purposes for which HTTP currently has no better mechanism.
2655</t>
2656<t>
2657   Some methods, like TRACE (<xref target="TRACE"/>) may expose
2658   information sent in request headers in the response entity.
2659   Clients &SHOULD; be careful with sensitive information, like Cookies,
2660   Authorization credentials and other headers that might be used to
2661   collect data from the client.
2662</t> 
2663</section>
2664
2665<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2666<t>
2667   Because the source of a link might be private information or might
2668   reveal an otherwise private information source, it is strongly
2669   recommended that the user be able to select whether or not the
2670   Referer field is sent. For example, a browser client could have a
2671   toggle switch for browsing openly/anonymously, which would
2672   respectively enable/disable the sending of Referer and From
2673   information.
2674</t>
2675<t>
2676   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2677   HTTP request if the referring page was transferred with a secure
2678   protocol.
2679</t>
2680<t>
2681   Authors of services should not use
2682   GET-based forms for the submission of sensitive data because that
2683   data will be encoded in the Request-target. Many existing
2684   servers, proxies, and user agents log or display the Request-target in
2685   places where it might be visible to third parties. Such services can
2686   use POST-based form submission instead.
2687</t>
2688</section>
2689
2690<section title="Location Headers and Spoofing" anchor="location.spoofing">
2691<t>
2692   If a single server supports multiple organizations that do not trust
2693   one another, then it &MUST; check the values of Location and Content-Location
2694   headers in responses that are generated under control of
2695   said organizations to make sure that they do not attempt to
2696   invalidate resources over which they have no authority.
2697</t>
2698</section>
2699
2700</section>
2701
2702<section title="Acknowledgments" anchor="ack">
2703</section>
2704</middle>
2705<back>
2706
2707<references title="Normative References">
2708
2709<reference anchor="Part1">
2710  <front>
2711    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2712    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2713      <organization abbrev="Day Software">Day Software</organization>
2714      <address><email>fielding@gbiv.com</email></address>
2715    </author>
2716    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2717      <organization>One Laptop per Child</organization>
2718      <address><email>jg@laptop.org</email></address>
2719    </author>
2720    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2721      <organization abbrev="HP">Hewlett-Packard Company</organization>
2722      <address><email>JeffMogul@acm.org</email></address>
2723    </author>
2724    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2725      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2726      <address><email>henrikn@microsoft.com</email></address>
2727    </author>
2728    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2729      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2730      <address><email>LMM@acm.org</email></address>
2731    </author>
2732    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2733      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2734      <address><email>paulle@microsoft.com</email></address>
2735    </author>
2736    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2737      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2738      <address><email>timbl@w3.org</email></address>
2739    </author>
2740    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2741      <organization abbrev="W3C">World Wide Web Consortium</organization>
2742      <address><email>ylafon@w3.org</email></address>
2743    </author>
2744    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2745      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2746      <address><email>julian.reschke@greenbytes.de</email></address>
2747    </author>
2748    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2749  </front>
2750  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
2751  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
2752</reference>
2753
2754<reference anchor="Part3">
2755  <front>
2756    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
2757    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2758      <organization abbrev="Day Software">Day Software</organization>
2759      <address><email>fielding@gbiv.com</email></address>
2760    </author>
2761    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2762      <organization>One Laptop per Child</organization>
2763      <address><email>jg@laptop.org</email></address>
2764    </author>
2765    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2766      <organization abbrev="HP">Hewlett-Packard Company</organization>
2767      <address><email>JeffMogul@acm.org</email></address>
2768    </author>
2769    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2770      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2771      <address><email>henrikn@microsoft.com</email></address>
2772    </author>
2773    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2774      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2775      <address><email>LMM@acm.org</email></address>
2776    </author>
2777    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2778      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2779      <address><email>paulle@microsoft.com</email></address>
2780    </author>
2781    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2782      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2783      <address><email>timbl@w3.org</email></address>
2784    </author>
2785    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2786      <organization abbrev="W3C">World Wide Web Consortium</organization>
2787      <address><email>ylafon@w3.org</email></address>
2788    </author>
2789    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2790      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2791      <address><email>julian.reschke@greenbytes.de</email></address>
2792    </author>
2793    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2794  </front>
2795  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
2796  <x:source href="p3-payload.xml" basename="p3-payload"/>
2797</reference>
2798
2799<reference anchor="Part4">
2800  <front>
2801    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
2802    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2803      <organization abbrev="Day Software">Day Software</organization>
2804      <address><email>fielding@gbiv.com</email></address>
2805    </author>
2806    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2807      <organization>One Laptop per Child</organization>
2808      <address><email>jg@laptop.org</email></address>
2809    </author>
2810    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2811      <organization abbrev="HP">Hewlett-Packard Company</organization>
2812      <address><email>JeffMogul@acm.org</email></address>
2813    </author>
2814    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2815      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2816      <address><email>henrikn@microsoft.com</email></address>
2817    </author>
2818    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2819      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2820      <address><email>LMM@acm.org</email></address>
2821    </author>
2822    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2823      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2824      <address><email>paulle@microsoft.com</email></address>
2825    </author>
2826    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2827      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2828      <address><email>timbl@w3.org</email></address>
2829    </author>
2830    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2831      <organization abbrev="W3C">World Wide Web Consortium</organization>
2832      <address><email>ylafon@w3.org</email></address>
2833    </author>
2834    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2835      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2836      <address><email>julian.reschke@greenbytes.de</email></address>
2837    </author>
2838    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2839  </front>
2840  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
2841  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
2842</reference>
2843
2844<reference anchor="Part5">
2845  <front>
2846    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
2847    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2848      <organization abbrev="Day Software">Day Software</organization>
2849      <address><email>fielding@gbiv.com</email></address>
2850    </author>
2851    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2852      <organization>One Laptop per Child</organization>
2853      <address><email>jg@laptop.org</email></address>
2854    </author>
2855    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2856      <organization abbrev="HP">Hewlett-Packard Company</organization>
2857      <address><email>JeffMogul@acm.org</email></address>
2858    </author>
2859    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2860      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2861      <address><email>henrikn@microsoft.com</email></address>
2862    </author>
2863    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2864      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2865      <address><email>LMM@acm.org</email></address>
2866    </author>
2867    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2868      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2869      <address><email>paulle@microsoft.com</email></address>
2870    </author>
2871    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2872      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2873      <address><email>timbl@w3.org</email></address>
2874    </author>
2875    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2876      <organization abbrev="W3C">World Wide Web Consortium</organization>
2877      <address><email>ylafon@w3.org</email></address>
2878    </author>
2879    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2880      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2881      <address><email>julian.reschke@greenbytes.de</email></address>
2882    </author>
2883    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2884  </front>
2885  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
2886  <x:source href="p5-range.xml" basename="p5-range"/>
2887</reference>
2888
2889<reference anchor="Part6">
2890  <front>
2891    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
2892    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2893      <organization abbrev="Day Software">Day Software</organization>
2894      <address><email>fielding@gbiv.com</email></address>
2895    </author>
2896    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2897      <organization>One Laptop per Child</organization>
2898      <address><email>jg@laptop.org</email></address>
2899    </author>
2900    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2901      <organization abbrev="HP">Hewlett-Packard Company</organization>
2902      <address><email>JeffMogul@acm.org</email></address>
2903    </author>
2904    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2905      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2906      <address><email>henrikn@microsoft.com</email></address>
2907    </author>
2908    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2909      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2910      <address><email>LMM@acm.org</email></address>
2911    </author>
2912    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2913      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2914      <address><email>paulle@microsoft.com</email></address>
2915    </author>
2916    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2917      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2918      <address><email>timbl@w3.org</email></address>
2919    </author>
2920    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2921      <organization abbrev="W3C">World Wide Web Consortium</organization>
2922      <address><email>ylafon@w3.org</email></address>
2923    </author>
2924    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
2925      <organization />
2926      <address><email>mnot@mnot.net</email></address>
2927    </author>
2928    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2929      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2930      <address><email>julian.reschke@greenbytes.de</email></address>
2931    </author>
2932    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2933  </front>
2934  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
2935  <x:source href="p6-cache.xml" basename="p6-cache"/>
2936</reference>
2937
2938<reference anchor="Part7">
2939  <front>
2940    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
2941    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2942      <organization abbrev="Day Software">Day Software</organization>
2943      <address><email>fielding@gbiv.com</email></address>
2944    </author>
2945    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2946      <organization>One Laptop per Child</organization>
2947      <address><email>jg@laptop.org</email></address>
2948    </author>
2949    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2950      <organization abbrev="HP">Hewlett-Packard Company</organization>
2951      <address><email>JeffMogul@acm.org</email></address>
2952    </author>
2953    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2954      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2955      <address><email>henrikn@microsoft.com</email></address>
2956    </author>
2957    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2958      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2959      <address><email>LMM@acm.org</email></address>
2960    </author>
2961    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2962      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2963      <address><email>paulle@microsoft.com</email></address>
2964    </author>
2965    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2966      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2967      <address><email>timbl@w3.org</email></address>
2968    </author>
2969    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2970      <organization abbrev="W3C">World Wide Web Consortium</organization>
2971      <address><email>ylafon@w3.org</email></address>
2972    </author>
2973    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2974      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2975      <address><email>julian.reschke@greenbytes.de</email></address>
2976    </author>
2977    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2978  </front>
2979  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
2980  <x:source href="p7-auth.xml" basename="p7-auth"/>
2981</reference>
2982
2983<reference anchor="RFC2119">
2984  <front>
2985    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
2986    <author initials="S." surname="Bradner" fullname="Scott Bradner">
2987      <organization>Harvard University</organization>
2988      <address><email>sob@harvard.edu</email></address>
2989    </author>
2990    <date month="March" year="1997"/>
2991  </front>
2992  <seriesInfo name="BCP" value="14"/>
2993  <seriesInfo name="RFC" value="2119"/>
2994</reference>
2995
2996<reference anchor="RFC5234">
2997  <front>
2998    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
2999    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3000      <organization>Brandenburg InternetWorking</organization>
3001      <address>
3002      <postal>
3003      <street>675 Spruce Dr.</street>
3004      <city>Sunnyvale</city>
3005      <region>CA</region>
3006      <code>94086</code>
3007      <country>US</country></postal>
3008      <phone>+1.408.246.8253</phone>
3009      <email>dcrocker@bbiw.net</email></address> 
3010    </author>
3011    <author initials="P." surname="Overell" fullname="Paul Overell">
3012      <organization>THUS plc.</organization>
3013      <address>
3014      <postal>
3015      <street>1/2 Berkeley Square</street>
3016      <street>99 Berkely Street</street>
3017      <city>Glasgow</city>
3018      <code>G3 7HR</code>
3019      <country>UK</country></postal>
3020      <email>paul.overell@thus.net</email></address>
3021    </author>
3022    <date month="January" year="2008"/>
3023  </front>
3024  <seriesInfo name="STD" value="68"/>
3025  <seriesInfo name="RFC" value="5234"/>
3026</reference>
3027
3028</references>
3029
3030<references title="Informative References">
3031
3032<reference anchor="RFC1945">
3033  <front>
3034    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3035    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3036      <organization>MIT, Laboratory for Computer Science</organization>
3037      <address><email>timbl@w3.org</email></address>
3038    </author>
3039    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3040      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3041      <address><email>fielding@ics.uci.edu</email></address>
3042    </author>
3043    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3044      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3045      <address><email>frystyk@w3.org</email></address>
3046    </author>
3047    <date month="May" year="1996"/>
3048  </front>
3049  <seriesInfo name="RFC" value="1945"/>
3050</reference>
3051
3052<reference anchor="RFC2068">
3053  <front>
3054    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3055    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3056      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3057      <address><email>fielding@ics.uci.edu</email></address>
3058    </author>
3059    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3060      <organization>MIT Laboratory for Computer Science</organization>
3061      <address><email>jg@w3.org</email></address>
3062    </author>
3063    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3064      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3065      <address><email>mogul@wrl.dec.com</email></address>
3066    </author>
3067    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3068      <organization>MIT Laboratory for Computer Science</organization>
3069      <address><email>frystyk@w3.org</email></address>
3070    </author>
3071    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3072      <organization>MIT Laboratory for Computer Science</organization>
3073      <address><email>timbl@w3.org</email></address>
3074    </author>
3075    <date month="January" year="1997"/>
3076  </front>
3077  <seriesInfo name="RFC" value="2068"/>
3078</reference>
3079
3080<reference anchor="RFC2616">
3081  <front>
3082    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3083    <author initials="R." surname="Fielding" fullname="R. Fielding">
3084      <organization>University of California, Irvine</organization>
3085      <address><email>fielding@ics.uci.edu</email></address>
3086    </author>
3087    <author initials="J." surname="Gettys" fullname="J. Gettys">
3088      <organization>W3C</organization>
3089      <address><email>jg@w3.org</email></address>
3090    </author>
3091    <author initials="J." surname="Mogul" fullname="J. Mogul">
3092      <organization>Compaq Computer Corporation</organization>
3093      <address><email>mogul@wrl.dec.com</email></address>
3094    </author>
3095    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3096      <organization>MIT Laboratory for Computer Science</organization>
3097      <address><email>frystyk@w3.org</email></address>
3098    </author>
3099    <author initials="L." surname="Masinter" fullname="L. Masinter">
3100      <organization>Xerox Corporation</organization>
3101      <address><email>masinter@parc.xerox.com</email></address>
3102    </author>
3103    <author initials="P." surname="Leach" fullname="P. Leach">
3104      <organization>Microsoft Corporation</organization>
3105      <address><email>paulle@microsoft.com</email></address>
3106    </author>
3107    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3108      <organization>W3C</organization>
3109      <address><email>timbl@w3.org</email></address>
3110    </author>
3111    <date month="June" year="1999"/>
3112  </front>
3113  <seriesInfo name="RFC" value="2616"/>
3114</reference>
3115
3116<reference anchor='RFC2817'>
3117  <front>
3118    <title>Upgrading to TLS Within HTTP/1.1</title>
3119    <author initials='R.' surname='Khare' fullname='R. Khare'>
3120      <organization>4K Associates / UC Irvine</organization>
3121      <address><email>rohit@4K-associates.com</email></address>
3122    </author>
3123    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3124      <organization>Agranat Systems, Inc.</organization>
3125      <address><email>lawrence@agranat.com</email></address>
3126    </author>
3127    <date year='2000' month='May' />
3128  </front>
3129  <seriesInfo name='RFC' value='2817' />
3130</reference>
3131
3132<reference anchor='RFC3864'>
3133  <front>
3134    <title>Registration Procedures for Message Header Fields</title>
3135    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3136      <organization>Nine by Nine</organization>
3137      <address><email>GK-IETF@ninebynine.org</email></address>
3138    </author>
3139    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3140      <organization>BEA Systems</organization>
3141      <address><email>mnot@pobox.com</email></address>
3142    </author>
3143    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3144      <organization>HP Labs</organization>
3145      <address><email>JeffMogul@acm.org</email></address>
3146    </author>
3147    <date year='2004' month='September' />
3148  </front>
3149  <seriesInfo name='BCP' value='90' />
3150  <seriesInfo name='RFC' value='3864' />
3151</reference>
3152
3153<reference anchor='RFC5226'>
3154  <front>
3155    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3156    <author initials='T.' surname='Narten' fullname='T. Narten'>
3157      <organization>IBM</organization>
3158      <address><email>narten@us.ibm.com</email></address>
3159    </author>
3160    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3161      <organization>Google</organization>
3162      <address><email>Harald@Alvestrand.no</email></address>
3163    </author>
3164    <date year='2008' month='May' />
3165  </front>
3166  <seriesInfo name='BCP' value='26' />
3167  <seriesInfo name='RFC' value='5226' />
3168</reference>
3169
3170<reference anchor="RFC5322">
3171  <front>
3172    <title>Internet Message Format</title>
3173    <author initials="P." surname="Resnick" fullname="P. Resnick">
3174      <organization>Qualcomm Incorporated</organization>
3175    </author>
3176    <date year="2008" month="October"/>
3177  </front> 
3178  <seriesInfo name="RFC" value="5322"/>
3179</reference>
3180
3181</references>
3182
3183<section title="Compatibility with Previous Versions" anchor="compatibility">
3184<section title="Changes from RFC 2068" anchor="changes.from.rfc.2068">
3185<t>
3186   Clarified which error code should be used for inbound server failures
3187   (e.g. DNS failures). (<xref target="status.504"/>).
3188</t>
3189<t>
3190   201 (Created) had a race that required an Etag be sent when a resource is
3191   first created. (<xref target="status.201"/>).
3192</t>
3193<t>
3194   303 (See Also) and 307 (Temporary Redirect) added to address user agent
3195   failure to implement status code 302 properly.
3196   (Section <xref target="status.303" format="counter"/> and <xref target="status.307" format="counter"/>)
3197</t>
3198<t>
3199   Rewrite of message transmission requirements to make it much harder
3200   for implementors to get it wrong, as the consequences of errors here
3201   can have significant impact on the Internet, and to deal with the
3202   following problems:
3203  <list style="numbers">
3204      <t>Changing "HTTP/1.1 or later" to "HTTP/1.1", in contexts where
3205         this was incorrectly placing a requirement on the behavior of
3206         an implementation of a future version of HTTP/1.x</t>
3207
3208      <t>Made it clear that user-agents should retry requests, not
3209         "clients" in general.</t>
3210
3211      <t>Converted requirements for clients to ignore unexpected 100
3212         (Continue) responses, and for proxies to forward 100 responses,
3213         into a general requirement for 1xx responses.</t>
3214
3215      <t>Modified some TCP-specific language, to make it clearer that
3216         non-TCP transports are possible for HTTP.</t>
3217
3218      <t>Require that the origin server &MUST-NOT; wait for the request
3219         body before it sends a required 100 (Continue) response.</t>
3220
3221      <t>Allow, rather than require, a server to omit 100 (Continue) if
3222         it has already seen some of the request body.</t>
3223
3224      <t>Allow servers to defend against denial-of-service attacks and
3225         broken clients.</t>
3226  </list>
3227</t>
3228<t>
3229   This change adds the Expect header and 417 status code.
3230</t>
3231<t>
3232   Clean up confusion between 403 and 404 responses. (Section <xref target="status.403" format="counter"/>,
3233   <xref target="status.404" format="counter"/>, and <xref target="status.410" format="counter"/>)
3234</t>
3235<t>
3236   The PATCH<iref item="PATCH method" primary="true"/><iref item="Methods" subitem="PATCH" primary="true"/>, LINK<iref item="LINK method" primary="true"/><iref item="Methods" subitem="LINK" primary="true"/>, UNLINK<iref item="UNLINK method" primary="true"/><iref item="Methods" subitem="UNLINK" primary="true"/> methods were defined but not commonly
3237   implemented in previous versions of this specification. See <xref target="RFC2068" x:fmt="of" x:sec="19.6.1"/>.
3238</t>
3239</section>
3240
3241<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3242<t>
3243  This document takes over the Status Code Registry, previously defined
3244  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3245  (<xref target="status.code.registry"/>)
3246</t>
3247<t>
3248  Clarify definition of POST.
3249  (<xref target="POST"/>)
3250</t>
3251<t>
3252  Failed to consider that there are
3253  many other request methods that are safe to automatically redirect,
3254  and further that the user agent is able to make that determination
3255  based on the request method semantics.
3256  (Sections <xref format="counter" target="status.301"/>,
3257  <xref format="counter" target="status.302"/> and
3258  <xref format="counter" target="status.307"/>)
3259</t>
3260<t>
3261  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3262  It used to indicate that the requested resource must be accessed through the
3263  proxy given by the Location field. The Location field gave the URI of the
3264  proxy. The recipient was expected to repeat this single request via the proxy.
3265  (<xref target="status.305"/>)
3266</t>
3267<t>
3268  Reclassify Allow header as response header, removing the option to
3269  specify it in a PUT request.
3270  Relax the server requirement on the contents of the Allow header and
3271  remove requirement on clients to always trust the header value.
3272  (<xref target="header.allow"/>)
3273</t>
3274<t>
3275  Correct syntax of Location header to allow fragment,
3276  as referred symbol wasn't what was expected, and add some
3277  clarifications as to when it would not be appropriate.
3278  (<xref target="header.location"/>)
3279</t>
3280<t>
3281  Allow Referer value of "about:blank" as alternative to not specifying it.
3282  (<xref target="header.referer"/>)
3283</t>
3284<t>
3285  In the description of the Server header, the Via field
3286  was described as a SHOULD. The requirement was and is stated
3287  correctly in the description of the Via header in &header-via;.
3288  (<xref target="header.server"/>)
3289</t>
3290</section>
3291
3292</section>
3293
3294<?BEGININC p2-semantics.abnf-appendix ?>
3295<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3296<figure>
3297<artwork type="abnf" name="p2-semantics.parsed-abnf">
3298<x:ref>Accept</x:ref> = &lt;Accept, defined in [Part3], Section 5.1&gt;
3299<x:ref>Accept-Charset</x:ref> = &lt;Accept-Charset, defined in [Part3], Section 5.2&gt;
3300<x:ref>Accept-Encoding</x:ref> = &lt;Accept-Encoding, defined in [Part3], Section 5.3&gt;
3301<x:ref>Accept-Language</x:ref> = &lt;Accept-Language, defined in [Part3], Section 5.4&gt;
3302<x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in [Part5], Section 5.1&gt;
3303<x:ref>Age</x:ref> = &lt;Age, defined in [Part6], Section 3.1&gt;
3304<x:ref>Allow</x:ref> = "Allow:" OWS Allow-v
3305<x:ref>Allow-v</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3306<x:ref>Authorization</x:ref> = &lt;Authorization, defined in [Part7], Section 3.1&gt;
3307
3308<x:ref>ETag</x:ref> = &lt;ETag, defined in [Part4], Section 6.1&gt;
3309<x:ref>Expect</x:ref> = "Expect:" OWS Expect-v
3310<x:ref>Expect-v</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3311
3312<x:ref>From</x:ref> = "From:" OWS From-v
3313<x:ref>From-v</x:ref> = mailbox
3314
3315<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3316<x:ref>Host</x:ref> = &lt;Host, defined in [Part1], Section 2.6&gt;
3317
3318<x:ref>If-Match</x:ref> = &lt;If-Match, defined in [Part4], Section 6.2&gt;
3319If-Modified-Since =
3320 &lt;If-Modified-Since, defined in [Part4], Section 6.3&gt;
3321<x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in [Part4], Section 6.4&gt;
3322<x:ref>If-Range</x:ref> = &lt;If-Range, defined in [Part5], Section 5.3&gt;
3323If-Unmodified-Since =
3324 &lt;If-Unmodified-Since, defined in [Part4], Section 6.5&gt;
3325
3326<x:ref>Location</x:ref> = "Location:" OWS Location-v
3327<x:ref>Location-v</x:ref> = URI
3328
3329<x:ref>Max-Forwards</x:ref> = "Max-Forwards:" OWS Max-Forwards-v
3330<x:ref>Max-Forwards-v</x:ref> = 1*DIGIT
3331<x:ref>Method</x:ref> = %x4F.50.54.49.4F.4E.53 ; OPTIONS
3332 / %x47.45.54 ; GET
3333 / %x48.45.41.44 ; HEAD
3334 / %x50.4F.53.54 ; POST
3335 / %x50.55.54 ; PUT
3336 / %x44.45.4C.45.54.45 ; DELETE
3337 / %x54.52.41.43.45 ; TRACE
3338 / %x43.4F.4E.4E.45.43.54 ; CONNECT
3339 / extension-method
3340
3341<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3342
3343Proxy-Authenticate =
3344 &lt;Proxy-Authenticate, defined in [Part7], Section 3.2&gt;
3345Proxy-Authorization =
3346 &lt;Proxy-Authorization, defined in [Part7], Section 3.3&gt;
3347
3348<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3349<x:ref>Range</x:ref> = &lt;Range, defined in [Part5], Section 5.4&gt;
3350<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3351<x:ref>Referer</x:ref> = "Referer:" OWS Referer-v
3352<x:ref>Referer-v</x:ref> = absolute-URI / partial-URI
3353<x:ref>Retry-After</x:ref> = "Retry-After:" OWS Retry-After-v
3354<x:ref>Retry-After-v</x:ref> = HTTP-date / delta-seconds
3355
3356<x:ref>Server</x:ref> = "Server:" OWS Server-v
3357<x:ref>Server-v</x:ref> = product *( RWS ( product / comment ) )
3358<x:ref>Status-Code</x:ref> = "100" / "101" / "200" / "201" / "202" / "203" / "204" /
3359 "205" / "206" / "300" / "301" / "302" / "303" / "304" / "305" /
3360 "307" / "400" / "401" / "402" / "403" / "404" / "405" / "406" /
3361 "407" / "408" / "409" / "410" / "411" / "412" / "413" / "414" /
3362 "415" / "416" / "417" / "500" / "501" / "502" / "503" / "504" /
3363 "505" / extension-code
3364
3365<x:ref>TE</x:ref> = &lt;TE, defined in [Part1], Section 9.8&gt;
3366
3367<x:ref>URI</x:ref> = &lt;URI, defined in [Part1], Section 2.6&gt;
3368<x:ref>User-Agent</x:ref> = "User-Agent:" OWS User-Agent-v
3369<x:ref>User-Agent-v</x:ref> = product *( RWS ( product / comment ) )
3370
3371<x:ref>Vary</x:ref> = &lt;Vary, defined in [Part6], Section 3.5&gt;
3372
3373WWW-Authenticate =
3374 &lt;WWW-Authenticate, defined in [Part7], Section 3.4&gt;
3375
3376<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
3377
3378<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3379
3380<x:ref>delta-seconds</x:ref> = 1*DIGIT
3381
3382<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3383<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3384<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3385 *expect-params ]
3386<x:ref>extension-code</x:ref> = 3DIGIT
3387<x:ref>extension-method</x:ref> = token
3388
3389<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3390
3391<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3392
3393<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
3394<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3395
3396<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3397
3398<x:ref>request-header</x:ref> = Accept / Accept-Charset / Accept-Encoding /
3399 Accept-Language / Authorization / Expect / From / Host / If-Match /
3400 If-Modified-Since / If-None-Match / If-Range / If-Unmodified-Since /
3401 Max-Forwards / Proxy-Authorization / Range / Referer / TE /
3402 User-Agent
3403<x:ref>response-header</x:ref> = Accept-Ranges / Age / Allow / ETag / Location /
3404 Proxy-Authenticate / Retry-After / Server / Vary / WWW-Authenticate
3405
3406<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3407</artwork>
3408</figure>
3409<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3410; Reason-Phrase defined but not used
3411; Status-Code defined but not used
3412; request-header defined but not used
3413; response-header defined but not used
3414</artwork></figure></section>
3415<?ENDINC p2-semantics.abnf-appendix ?>
3416
3417<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3418
3419<section title="Since RFC2616">
3420<t>
3421  Extracted relevant partitions from <xref target="RFC2616"/>.
3422</t>
3423</section>
3424
3425<section title="Since draft-ietf-httpbis-p2-semantics-00">
3426<t>
3427  Closed issues:
3428  <list style="symbols"> 
3429    <t>
3430      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3431      "Via is a MUST"
3432      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3433    </t>
3434    <t>
3435      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3436      "Fragments allowed in Location"
3437      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3438    </t>
3439    <t>
3440      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3441      "Safe Methods vs Redirection"
3442      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3443    </t>
3444    <t>
3445      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3446      "Revise description of the POST method"
3447      (<eref target="http://purl.org/NET/http-errata#post"/>)
3448    </t>
3449    <t>
3450      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3451      "Normative and Informative references"
3452    </t>
3453    <t>
3454      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3455      "RFC2606 Compliance"
3456    </t>
3457    <t>
3458      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3459      "Informative references"
3460    </t>
3461    <t>
3462      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3463      "Redundant cross-references"
3464    </t>
3465  </list>
3466</t>
3467<t>
3468  Other changes:
3469  <list style="symbols"> 
3470    <t>
3471      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3472    </t>
3473  </list>
3474</t>
3475</section>
3476
3477<section title="Since draft-ietf-httpbis-p2-semantics-01">
3478<t>
3479  Closed issues:
3480  <list style="symbols"> 
3481    <t>
3482      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3483      "PUT side effects"
3484    </t>
3485    <t>
3486      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3487      "Duplicate Host header requirements"
3488    </t>
3489  </list>
3490</t>
3491<t>
3492  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3493  <list style="symbols"> 
3494    <t>
3495      Move "Product Tokens" section (back) into Part 1, as "token" is used
3496      in the definition of the Upgrade header.
3497    </t>
3498    <t>
3499      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3500    </t>
3501    <t>
3502      Copy definition of delta-seconds from Part6 instead of referencing it.
3503    </t>
3504  </list>
3505</t>
3506</section>
3507
3508<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3509<t>
3510  Closed issues:
3511  <list style="symbols"> 
3512    <t>
3513      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3514      "Requiring Allow in 405 responses"
3515    </t>
3516    <t>
3517      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3518      "Status Code Registry"
3519    </t>
3520    <t>
3521      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3522      "Redirection vs. Location"
3523    </t>
3524    <t>
3525      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3526      "Cacheability of 303 response"
3527    </t>
3528    <t>
3529      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3530      "305 Use Proxy"
3531    </t>
3532    <t>
3533      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3534      "Classification for Allow header"
3535    </t>
3536    <t>
3537      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3538      "PUT - 'store under' vs 'store at'"
3539    </t>
3540  </list>
3541</t>
3542<t>
3543  Ongoing work on IANA Message Header Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3544  <list style="symbols"> 
3545    <t>
3546      Reference RFC 3984, and update header registrations for headers defined
3547      in this document.
3548    </t>
3549  </list>
3550</t>
3551<t>
3552  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3553  <list style="symbols"> 
3554    <t>
3555      Replace string literals when the string really is case-sensitive (method).
3556    </t>
3557  </list>
3558</t>
3559</section>
3560
3561<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3562<t>
3563  Closed issues:
3564  <list style="symbols"> 
3565    <t>
3566      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3567      "OPTIONS request bodies"
3568    </t>
3569    <t>
3570      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3571      "Description of CONNECT should refer to RFC2817"
3572    </t>
3573    <t>
3574      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3575      "Location Content-Location reference request/response mixup"
3576    </t>
3577  </list>
3578</t>
3579<t>
3580  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3581  <list style="symbols"> 
3582    <t>
3583      Added initial proposal for registration process, plus initial
3584      content (non-HTTP/1.1 methods to be added by a separate specification).
3585    </t>
3586  </list>
3587</t>
3588</section>
3589
3590<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3591<t>
3592  Closed issues:
3593  <list style="symbols"> 
3594    <t>
3595      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3596      "Content-*"
3597    </t>
3598    <t>
3599      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3600      "RFC 2822 is updated by RFC 5322"
3601    </t>
3602  </list>
3603</t>
3604<t>
3605  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3606  <list style="symbols"> 
3607    <t>
3608      Use "/" instead of "|" for alternatives.
3609    </t>
3610    <t>
3611      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3612      whitespace ("OWS") and required whitespace ("RWS").
3613    </t>
3614    <t>
3615      Rewrite ABNFs to spell out whitespace rules, factor out
3616      header value format definitions.
3617    </t>
3618  </list>
3619</t>
3620</section>
3621
3622<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3623<t>
3624  Closed issues:
3625  <list style="symbols"> 
3626    <t>
3627      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3628      "Reason-Phrase BNF"
3629    </t>
3630  </list>
3631</t>
3632<t>
3633  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3634  <list style="symbols"> 
3635    <t>
3636      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3637    </t>
3638  </list>
3639</t>
3640</section>
3641
3642<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3643<t>
3644  Closed issues:
3645  <list style="symbols"> 
3646    <t>
3647      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3648      "Clarify when Referer is sent"
3649    </t>
3650    <t>
3651      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3652      "status codes vs methods"
3653    </t>
3654    <t>
3655      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3656      "Do not require "updates" relation for specs that register status codes or method names"
3657    </t>
3658  </list>
3659</t>
3660</section>
3661
3662<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3663<t>
3664  Closed issues:
3665  <list style="symbols"> 
3666    <t>
3667      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3668      "Idempotency"
3669    </t>
3670    <t>
3671      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3672      "TRACE security considerations"
3673    </t>
3674    <t>
3675      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3676      "Clarify rules for determining what entities a response carries"
3677    </t>
3678    <t>
3679      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3680      "update note citing RFC 1945 and 2068"
3681    </t>
3682    <t>
3683      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3684      "update note about redirect limit"
3685    </t>
3686    <t>
3687      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3688      "Location header ABNF should use 'URI'"
3689    </t>
3690    <t>
3691      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3692      "fragments in Location vs status 303"
3693    </t>
3694  </list>
3695</t>
3696</section>
3697
3698</section>
3699
3700</back>
3701</rfc>
Note: See TracBrowser for help on using the repository browser.