source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1066

Last change on this file since 1066 was 1066, checked in by julian.reschke@…, 9 years ago

Note that we now define CONNECT (see #239)

  • Property svn:eol-style set to native
File size: 168.0 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 "October">
16  <!ENTITY ID-YEAR "2010">
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 combining-responses        "<xref target='Part6' x:rel='#combining.responses' 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 effective-request-uri      "<xref target='Part1' x:rel='#effective.request.uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY full-date                  "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY http-url                   "<xref target='Part1' x:rel='#http-url' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY http-version               "<xref target='Part1' x:rel='#http.version' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY use100                     "<xref target='Part1' x:rel='#use.of.the.100.status' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY qvalue                     "<xref target='Part3' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35  <!ENTITY request-target             "<xref target='Part1' x:rel='#request-target' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY header-accept              "<xref target='Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY header-accept-charset      "<xref target='Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY header-accept-encoding     "<xref target='Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY header-accept-language     "<xref target='Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY header-accept-ranges       "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41  <!ENTITY header-age                 "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
42  <!ENTITY header-authorization       "<xref target='Part7' x:rel='#header.authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
43  <!ENTITY header-cache-control       "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
44  <!ENTITY header-content-location    "<xref target='Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
45  <!ENTITY header-content-range       "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
46  <!ENTITY header-etag                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
47  <!ENTITY header-expires             "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
48  <!ENTITY header-fields              "<xref target='Part1' x:rel='#header.fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
49  <!ENTITY header-host                "<xref target='Part1' x:rel='#header.host' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
50  <!ENTITY header-if-match            "<xref target='Part4' x:rel='#header.if-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
51  <!ENTITY header-if-modified-since   "<xref target='Part4' x:rel='#header.if-modified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
52  <!ENTITY header-if-none-match       "<xref target='Part4' x:rel='#header.if-none-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
53  <!ENTITY header-if-range            "<xref target='Part5' x:rel='#header.if-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
54  <!ENTITY header-if-unmodified-since "<xref target='Part4' x:rel='#header.if-unmodified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
55  <!ENTITY header-pragma              "<xref target='Part6' x:rel='#header.pragma' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
56  <!ENTITY header-proxy-authenticate  "<xref target='Part7' x:rel='#header.proxy-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
57  <!ENTITY header-proxy-authorization "<xref target='Part7' x:rel='#header.proxy-authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
58  <!ENTITY header-range               "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
59  <!ENTITY header-upgrade             "<xref target='Part1' x:rel='#header.upgrade' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
60  <!ENTITY header-te                  "<xref target='Part1' x:rel='#header.te' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
61  <!ENTITY header-vary                "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
62  <!ENTITY header-via                 "<xref target='Part1' x:rel='#header.via' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
63  <!ENTITY header-warning             "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
64  <!ENTITY header-www-authenticate    "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
65  <!ENTITY message-body               "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
66  <!ENTITY product-tokens             "<xref target='Part1' x:rel='#product.tokens' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
67  <!ENTITY media-type-message-http    "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
68  <!ENTITY status-206                 "<xref target='Part5' x:rel='#status.206' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
69  <!ENTITY status-304                 "<xref target='Part4' x:rel='#status.304' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
70  <!ENTITY status-401                 "<xref target='Part7' x:rel='#status.401' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
71  <!ENTITY status-407                 "<xref target='Part7' x:rel='#status.407' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
72  <!ENTITY status-412                 "<xref target='Part4' x:rel='#status.412' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
73  <!ENTITY status-416                 "<xref target='Part5' x:rel='#status.416' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
74  <!ENTITY p4-status-codes            "<xref target='Part4' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
75  <!ENTITY p5-status-codes            "<xref target='Part5' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
76  <!ENTITY p7-status-codes            "<xref target='Part7' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
77  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
78  <!ENTITY p6-explicit               "<xref target='Part6' x:rel='#calculating.freshness.lifetime' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
79]>
80<?rfc toc="yes" ?>
81<?rfc symrefs="yes" ?>
82<?rfc sortrefs="yes" ?>
83<?rfc compact="yes"?>
84<?rfc subcompact="no" ?>
85<?rfc linkmailto="no" ?>
86<?rfc editing="no" ?>
87<?rfc comments="yes"?>
88<?rfc inline="yes"?>
89<?rfc rfcedstyle="yes"?>
90<?rfc-ext allow-markup-in-artwork="yes" ?>
91<?rfc-ext include-references-in-index="yes" ?>
92<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
93     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
94     xmlns:x='http://purl.org/net/xml2rfc/ext'
95     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
96<front>
97
98  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
99
100  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
101    <organization abbrev="Day Software">Day Software</organization>
102    <address>
103      <postal>
104        <street>23 Corporate Plaza DR, Suite 280</street>
105        <city>Newport Beach</city>
106        <region>CA</region>
107        <code>92660</code>
108        <country>USA</country>
109      </postal>
110      <phone>+1-949-706-5300</phone>
111      <facsimile>+1-949-706-5305</facsimile>
112      <email>fielding@gbiv.com</email>
113      <uri>http://roy.gbiv.com/</uri>
114    </address>
115  </author>
116
117  <author initials="J." surname="Gettys" fullname="Jim Gettys">
118    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
119    <address>
120      <postal>
121        <street>21 Oak Knoll Road</street>
122        <city>Carlisle</city>
123        <region>MA</region>
124        <code>01741</code>
125        <country>USA</country>
126      </postal>
127      <email>jg@freedesktop.org</email>
128      <uri>http://gettys.wordpress.com/</uri>
129    </address>
130  </author>
131 
132  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
133    <organization abbrev="HP">Hewlett-Packard Company</organization>
134    <address>
135      <postal>
136        <street>HP Labs, Large Scale Systems Group</street>
137        <street>1501 Page Mill Road, MS 1177</street>
138        <city>Palo Alto</city>
139        <region>CA</region>
140        <code>94304</code>
141        <country>USA</country>
142      </postal>
143      <email>JeffMogul@acm.org</email>
144    </address>
145  </author>
146
147  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
148    <organization abbrev="Microsoft">Microsoft Corporation</organization>
149    <address>
150      <postal>
151        <street>1 Microsoft Way</street>
152        <city>Redmond</city>
153        <region>WA</region>
154        <code>98052</code>
155        <country>USA</country>
156      </postal>
157      <email>henrikn@microsoft.com</email>
158    </address>
159  </author>
160
161  <author initials="L." surname="Masinter" fullname="Larry Masinter">
162    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
163    <address>
164      <postal>
165        <street>345 Park Ave</street>
166        <city>San Jose</city>
167        <region>CA</region>
168        <code>95110</code>
169        <country>USA</country>
170      </postal>
171      <email>LMM@acm.org</email>
172      <uri>http://larry.masinter.net/</uri>
173    </address>
174  </author>
175 
176  <author initials="P." surname="Leach" fullname="Paul J. Leach">
177    <organization abbrev="Microsoft">Microsoft Corporation</organization>
178    <address>
179      <postal>
180        <street>1 Microsoft Way</street>
181        <city>Redmond</city>
182        <region>WA</region>
183        <code>98052</code>
184      </postal>
185      <email>paulle@microsoft.com</email>
186    </address>
187  </author>
188   
189  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
190    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
191    <address>
192      <postal>
193        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
194        <street>The Stata Center, Building 32</street>
195        <street>32 Vassar Street</street>
196        <city>Cambridge</city>
197        <region>MA</region>
198        <code>02139</code>
199        <country>USA</country>
200      </postal>
201      <email>timbl@w3.org</email>
202      <uri>http://www.w3.org/People/Berners-Lee/</uri>
203    </address>
204  </author>
205
206  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
207    <organization abbrev="W3C">World Wide Web Consortium</organization>
208    <address>
209      <postal>
210        <street>W3C / ERCIM</street>
211        <street>2004, rte des Lucioles</street>
212        <city>Sophia-Antipolis</city>
213        <region>AM</region>
214        <code>06902</code>
215        <country>France</country>
216      </postal>
217      <email>ylafon@w3.org</email>
218      <uri>http://www.raubacapeu.net/people/yves/</uri>
219    </address>
220  </author>
221
222  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
223    <organization abbrev="greenbytes">greenbytes GmbH</organization>
224    <address>
225      <postal>
226        <street>Hafenweg 16</street>
227        <city>Muenster</city><region>NW</region><code>48155</code>
228        <country>Germany</country>
229      </postal>
230      <phone>+49 251 2807760</phone>
231      <facsimile>+49 251 2807761</facsimile>
232      <email>julian.reschke@greenbytes.de</email>
233      <uri>http://greenbytes.de/tech/webdav/</uri>
234    </address>
235  </author>
236
237  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
238  <workgroup>HTTPbis Working Group</workgroup>
239
240<abstract>
241<t>
242   The Hypertext Transfer Protocol (HTTP) is an application-level
243   protocol for distributed, collaborative, hypermedia information
244   systems. HTTP has been in use by the World Wide Web global information
245   initiative since 1990. This document is Part 2 of the seven-part specification
246   that defines the protocol referred to as "HTTP/1.1" and, taken together,
247   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
248   as expressed by request methods, request-header fields, response status codes,
249   and response-header fields.
250</t>
251</abstract>
252
253<note title="Editorial Note (To be removed by RFC Editor)">
254  <t>
255    Discussion of this draft should take place on the HTTPBIS working group
256    mailing list (ietf-http-wg@w3.org). The current issues list is
257    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/>
258    and related documents (including fancy diffs) can be found at
259    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
260  </t>
261  <t>
262    The changes in this draft are summarized in <xref target="changes.since.12"/>.
263  </t>
264</note>
265</front>
266<middle>
267<section title="Introduction" anchor="introduction">
268<t>
269   This document defines HTTP/1.1 request and response semantics.  Each HTTP
270   message, as defined in &messaging;, is in the form of either a request or
271   a response.  An HTTP server listens on a connection for HTTP requests and
272   responds to each request, in the order received on that connection, with
273   one or more HTTP response messages.  This document defines the commonly
274   agreed upon semantics of the HTTP uniform interface, the intentions defined
275   by each request method, and the various response messages that might be
276   expected as a result of applying that method to the target resource.
277</t>
278<t>
279   This document is currently disorganized in order to minimize the changes
280   between drafts and enable reviewers to see the smaller errata changes.
281   A future draft will reorganize the sections to better reflect the content.
282   In particular, the sections will be ordered according to the typical
283   processing of an HTTP request message (after message parsing): resource
284   mapping, general header fields, methods, request modifiers, response
285   status, and resource metadata.  The current mess reflects how widely
286   dispersed these topics and associated requirements had become in
287   <xref target="RFC2616"/>.
288</t>
289
290<section title="Requirements" anchor="intro.requirements">
291<t>
292   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
293   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
294   document are to be interpreted as described in <xref target="RFC2119"/>.
295</t>
296<t>
297   An implementation is not compliant if it fails to satisfy one or more
298   of the "MUST" or "REQUIRED" level requirements for the protocols it
299   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
300   level and all the "SHOULD" level requirements for its protocols is said
301   to be "unconditionally compliant"; one that satisfies all the "MUST"
302   level requirements but not all the "SHOULD" level requirements for its
303   protocols is said to be "conditionally compliant".
304</t>
305</section>
306
307<section title="Syntax Notation" anchor="notation">
308  <x:anchor-alias value="CR"/>
309  <x:anchor-alias value="DIGIT"/>
310  <x:anchor-alias value="LF"/>
311  <x:anchor-alias value="VCHAR"/>
312  <x:anchor-alias value="WSP"/>
313<t>
314  This specification uses the ABNF syntax defined in &notation; (which
315  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
316  <xref target="collected.abnf"/> shows the collected ABNF, with the list
317  rule expanded.
318</t>
319<t>
320  The following core rules are included by
321  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
322  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
323  DIGIT (decimal 0-9), DQUOTE (double quote),
324  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
325  OCTET (any 8-bit sequence of data), SP (space),
326  VCHAR (any visible USASCII character),
327  and WSP (whitespace).
328</t>
329
330<section title="Core Rules" anchor="core.rules">
331  <x:anchor-alias value="obs-text"/>
332  <x:anchor-alias value="quoted-string"/>
333  <x:anchor-alias value="token"/>
334  <x:anchor-alias value="OWS"/>
335  <x:anchor-alias value="RWS"/>
336<t>
337  The core rules below are defined in &basic-rules;:
338</t>
339<figure><artwork type="abnf2616">
340  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
341  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
342  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
343  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
344  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
345</artwork></figure>
346</section>
347
348<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
349  <x:anchor-alias value="absolute-URI"/>
350  <x:anchor-alias value="Accept"/>
351  <x:anchor-alias value="Accept-Charset"/>
352  <x:anchor-alias value="Accept-Encoding"/>
353  <x:anchor-alias value="Accept-Language"/>
354  <x:anchor-alias value="Accept-Ranges"/>
355  <x:anchor-alias value="Age"/>
356  <x:anchor-alias value="Authorization"/>
357  <x:anchor-alias value="comment"/>
358  <x:anchor-alias value="ETag"/>
359  <x:anchor-alias value="Host"/>
360  <x:anchor-alias value="HTTP-date"/>
361  <x:anchor-alias value="If-Match"/>
362  <x:anchor-alias value="If-Modified-Since"/>
363  <x:anchor-alias value="If-None-Match"/>
364  <x:anchor-alias value="If-Range"/>
365  <x:anchor-alias value="If-Unmodified-Since"/>
366  <x:anchor-alias value="partial-URI"/>
367  <x:anchor-alias value="product"/>
368  <x:anchor-alias value="Proxy-Authenticate"/>
369  <x:anchor-alias value="Proxy-Authorization"/>
370  <x:anchor-alias value="Range"/>
371  <x:anchor-alias value="TE"/>
372  <x:anchor-alias value="URI-reference"/>
373  <x:anchor-alias value="Vary"/>
374  <x:anchor-alias value="WWW-Authenticate"/>
375<t>
376  The ABNF rules below are defined in other parts:
377</t>
378<figure><!--Part1--><artwork type="abnf2616">
379  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
380  <x:ref>comment</x:ref>       = &lt;comment, defined in &header-fields;&gt;
381  <x:ref>Host</x:ref>          = &lt;Host, defined in &uri;&gt;
382  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
383  <x:ref>partial-URI</x:ref>   = &lt;partial-URI, defined in &uri;&gt;
384  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
385  <x:ref>TE</x:ref>            = &lt;TE, defined in &header-te;&gt;
386  <x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in &uri;&gt;
387</artwork></figure>
388<figure><!--Part3--><artwork type="abnf2616">
389  <x:ref>Accept</x:ref>        = &lt;Accept, defined in &header-accept;&gt;
390  <x:ref>Accept-Charset</x:ref> =
391             &lt;Accept-Charset, defined in &header-accept-charset;&gt;
392  <x:ref>Accept-Encoding</x:ref> =
393             &lt;Accept-Encoding, defined in &header-accept-encoding;&gt;
394  <x:ref>Accept-Language</x:ref> =
395             &lt;Accept-Language, defined in &header-accept-language;&gt;
396</artwork></figure>
397<figure><!--Part4--><artwork type="abnf2616">
398  <x:ref>ETag</x:ref>          = &lt;ETag, defined in &header-etag;&gt;
399  <x:ref>If-Match</x:ref>      = &lt;If-Match, defined in &header-if-match;&gt;
400  <x:ref>If-Modified-Since</x:ref> =
401             &lt;If-Modified-Since, defined in &header-if-modified-since;&gt;
402  <x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in &header-if-none-match;&gt;
403  <x:ref>If-Unmodified-Since</x:ref> =
404             &lt;If-Unmodified-Since, defined in &header-if-unmodified-since;&gt;
405</artwork></figure>
406<figure><!--Part5--><artwork type="abnf2616">
407  <x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in &header-accept-ranges;&gt;
408  <x:ref>If-Range</x:ref>      = &lt;If-Range, defined in &header-if-range;&gt;
409  <x:ref>Range</x:ref>         = &lt;Range, defined in &header-range;&gt;
410</artwork></figure>
411<figure><!--Part6--><artwork type="abnf2616">
412  <x:ref>Age</x:ref>           = &lt;Age, defined in &header-age;&gt;
413  <x:ref>Vary</x:ref>          = &lt;Vary, defined in &header-vary;&gt;
414</artwork><!--Part7--></figure>
415<figure><artwork type="abnf2616">
416  <x:ref>Authorization</x:ref> = &lt;Authorization, defined in &header-authorization;&gt;
417  <x:ref>Proxy-Authenticate</x:ref> =
418             &lt;Proxy-Authenticate, defined in &header-proxy-authenticate;&gt;
419  <x:ref>Proxy-Authorization</x:ref> =
420             &lt;Proxy-Authorization, defined in &header-proxy-authorization;&gt;
421  <x:ref>WWW-Authenticate</x:ref> =
422             &lt;WWW-Authenticate, defined in &header-www-authenticate;&gt;
423</artwork></figure>
424</section>
425</section>
426</section>
427
428<section title="Method" anchor="method">
429  <x:anchor-alias value="Method"/>
430  <x:anchor-alias value="extension-method"/>
431<t>
432   The Method token indicates the method to be performed on the target
433   resource (&effective-request-uri;). The method is case-sensitive.
434</t>
435<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/><iref primary="true" item="Grammar" subitem="extension-method"/>
436  <x:ref>Method</x:ref>         = <x:abnf-char-sequence>"OPTIONS"</x:abnf-char-sequence>   ; "OPTIONS", <xref target="OPTIONS"/>
437                 / <x:abnf-char-sequence>"GET"</x:abnf-char-sequence>               ; "GET", <xref target="GET"/>
438                 / <x:abnf-char-sequence>"HEAD"</x:abnf-char-sequence>            ; "HEAD", <xref target="HEAD"/>
439                 / <x:abnf-char-sequence>"POST"</x:abnf-char-sequence>            ; "POST", <xref target="POST"/>
440                 / <x:abnf-char-sequence>"PUT"</x:abnf-char-sequence>               ; "PUT", <xref target="PUT"/>
441                 / <x:abnf-char-sequence>"DELETE"</x:abnf-char-sequence>      ; "DELETE", <xref target="DELETE"/>
442                 / <x:abnf-char-sequence>"TRACE"</x:abnf-char-sequence>         ; "TRACE", <xref target="TRACE"/>
443                 / <x:abnf-char-sequence>"CONNECT"</x:abnf-char-sequence>   ; "CONNECT", <xref target="CONNECT"/>
444                 / <x:ref>extension-method</x:ref>
445  <x:ref>extension-method</x:ref> = <x:ref>token</x:ref>
446</artwork></figure>
447<t>
448   The list of methods allowed by a resource can be specified in an
449   Allow header field (<xref target="header.allow"/>). The status code of the response
450   always notifies the client whether a method is currently allowed on a
451   resource, since the set of allowed methods can change dynamically. An
452   origin server &SHOULD; respond with the status code 405 (Method Not Allowed)
453   if the method is known by the origin server but not allowed for the
454   resource, and 501 (Not Implemented) if the method is
455   unrecognized or not implemented by the origin server. The methods GET
456   and HEAD &MUST; be supported by all general-purpose servers. All other
457   methods are &OPTIONAL;; however, if the above methods are implemented,
458   they &MUST; be implemented with the same semantics as those specified
459   in <xref target="method.definitions"/>.
460</t>
461
462<section title="Method Registry" anchor="method.registry">
463<t>
464  The HTTP Method Registry defines the name space for the Method token in the
465  Request line of an HTTP request.
466</t>
467<t>
468  Registrations &MUST; include the following fields:
469  <list style="symbols">
470    <t>Method Name (see <xref target="method"/>)</t>
471    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
472    <t>Pointer to specification text</t>
473  </list>
474</t>
475<t>
476  Values to be added to this name space are subject to IETF review
477  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
478</t>
479<t>
480  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
481</t>
482
483<section title="Considerations for New Methods" anchor="considerations.for.new.methods">
484<t>
485   When it is necessary to express new semantics for a HTTP request that
486   aren't specific to a single application or media type, and currently defined
487   methods are inadequate, it may be appropriate to register a new method.
488</t>
489<t>
490   HTTP methods are generic; that is, they are potentially applicable to any
491   resource, not just one particular media type, "type" of resource, or
492   application. As such, it is preferred that new HTTP methods be registered
493   in a document that isn't specific to a single application, so that this is
494   clear.
495</t>
496<t>
497   Due to the parsing rules defined in &message-body;, definitions of HTTP
498   methods cannot prohibit the presence of a message-body on either the request
499   or the response message (with responses to HEAD requests being the single
500   exception). Definitions of new methods cannot change this rule, but they can
501   specify that only zero-length bodies (as opposed to absent bodies) are allowed.
502</t>
503<t>
504   New method definitions need to indicate whether they are safe (<xref
505   target="safe.methods"/>) and whether they are idempotent (<xref
506   target="idempotent.methods"/>). They also need to state whether they can be
507   cached (&caching;); in particular what conditions a cache may store the
508   response, and under what conditions such a stored response may be used to
509   satisfy a subsequent request.
510</t>
511</section>
512
513</section>
514</section>
515
516<section title="Request Header Fields" anchor="request.header.fields">
517  <x:anchor-alias value="request-header"/>
518<t>
519   The request-header fields allow the client to pass additional
520   information about the request, and about the client itself, to the
521   server. These fields act as request modifiers, with semantics
522   equivalent to the parameters on a programming language method
523   invocation.
524</t>
525<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="request-header"/>
526  <x:ref>request-header</x:ref> = <x:ref>Accept</x:ref>                   ; &header-accept;
527                 / <x:ref>Accept-Charset</x:ref>           ; &header-accept-charset;
528                 / <x:ref>Accept-Encoding</x:ref>          ; &header-accept-encoding;
529                 / <x:ref>Accept-Language</x:ref>          ; &header-accept-language;
530                 / <x:ref>Authorization</x:ref>            ; &header-authorization;
531                 / <x:ref>Expect</x:ref>                   ; <xref target="header.expect"/>
532                 / <x:ref>From</x:ref>                     ; <xref target="header.from"/>
533                 / <x:ref>Host</x:ref>                     ; &header-host;
534                 / <x:ref>If-Match</x:ref>                 ; &header-if-match;
535                 / <x:ref>If-Modified-Since</x:ref>        ; &header-if-modified-since;
536                 / <x:ref>If-None-Match</x:ref>            ; &header-if-none-match;
537                 / <x:ref>If-Range</x:ref>                 ; &header-if-range;
538                 / <x:ref>If-Unmodified-Since</x:ref>      ; &header-if-unmodified-since;
539                 / <x:ref>Max-Forwards</x:ref>             ; <xref target="header.max-forwards"/>
540                 / <x:ref>Proxy-Authorization</x:ref>      ; &header-proxy-authorization;
541                 / <x:ref>Range</x:ref>                    ; &header-range;
542                 / <x:ref>Referer</x:ref>                  ; <xref target="header.referer"/>
543                 / <x:ref>TE</x:ref>                       ; &header-te;
544                 / <x:ref>User-Agent</x:ref>               ; <xref target="header.user-agent"/>
545</artwork></figure>
546<t>
547   Request-header field names can be extended reliably only in
548   combination with a change in the protocol version. However, new or
549   experimental header fields &MAY; be given the semantics of request-header
550   fields if all parties in the communication recognize them to
551   be request-header fields.
552</t>
553</section>
554
555<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
556  <x:anchor-alias value="Reason-Phrase"/>
557  <x:anchor-alias value="Status-Code"/>
558  <x:anchor-alias value="extension-code"/>
559<t>
560   The Status-Code element is a 3-digit integer result code of the
561   attempt to understand and satisfy the request. The status codes listed
562   below are defined in <xref target="status.codes"/>, &p4-status-codes;,
563   &p5-status-codes;, and &p7-status-codes;.
564</t>
565<t>
566   The Reason-Phrase is intended to give a short
567   textual description of the Status-Code. The Status-Code is intended
568   for use by automata and the Reason-Phrase is intended for the human
569   user. The client is not required to examine or display the Reason-Phrase.
570</t>
571<t> 
572   The individual values of the numeric status codes defined for
573   HTTP/1.1, and an example set of corresponding Reason-Phrase values, are
574   presented below. The reason phrases listed here are only
575   recommendations -- they &MAY; be replaced by local equivalents without
576   affecting the protocol.
577</t>
578<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"/>
579  <x:ref>Status-Code</x:ref> =
580       "100"  ; <xref target="status.100"/>: Continue
581     / "101"  ; <xref target="status.101"/>: Switching Protocols
582     / "200"  ; <xref target="status.200"/>: OK
583     / "201"  ; <xref target="status.201"/>: Created
584     / "202"  ; <xref target="status.202"/>: Accepted
585     / "203"  ; <xref target="status.203"/>: Non-Authoritative Information
586     / "204"  ; <xref target="status.204"/>: No Content
587     / "205"  ; <xref target="status.205"/>: Reset Content
588     / "206"  ; &status-206;: Partial Content
589     / "300"  ; <xref target="status.300"/>: Multiple Choices
590     / "301"  ; <xref target="status.301"/>: Moved Permanently
591     / "302"  ; <xref target="status.302"/>: Found
592     / "303"  ; <xref target="status.303"/>: See Other
593     / "304"  ; &status-304;: Not Modified
594     / "305"  ; <xref target="status.305"/>: Use Proxy
595     / "307"  ; <xref target="status.307"/>: Temporary Redirect
596     / "400"  ; <xref target="status.400"/>: Bad Request
597     / "401"  ; &status-401;: Unauthorized
598     / "402"  ; <xref target="status.402"/>: Payment Required
599     / "403"  ; <xref target="status.403"/>: Forbidden
600     / "404"  ; <xref target="status.404"/>: Not Found
601     / "405"  ; <xref target="status.405"/>: Method Not Allowed
602     / "406"  ; <xref target="status.406"/>: Not Acceptable
603     / "407"  ; &status-407;: Proxy Authentication Required
604     / "408"  ; <xref target="status.408"/>: Request Time-out
605     / "409"  ; <xref target="status.409"/>: Conflict
606     / "410"  ; <xref target="status.410"/>: Gone
607     / "411"  ; <xref target="status.411"/>: Length Required
608     / "412"  ; &status-412;: Precondition Failed
609     / "413"  ; <xref target="status.413"/>: Request Entity Too Large
610     / "414"  ; <xref target="status.414"/>: URI Too Long
611     / "415"  ; <xref target="status.415"/>: Unsupported Media Type
612     / "416"  ; &status-416;: Requested range not satisfiable
613     / "417"  ; <xref target="status.417"/>: Expectation Failed
614     / "500"  ; <xref target="status.500"/>: Internal Server Error
615     / "501"  ; <xref target="status.501"/>: Not Implemented
616     / "502"  ; <xref target="status.502"/>: Bad Gateway
617     / "503"  ; <xref target="status.503"/>: Service Unavailable
618     / "504"  ; <xref target="status.504"/>: Gateway Time-out
619     / "505"  ; <xref target="status.505"/>: HTTP Version not supported
620     / <x:ref>extension-code</x:ref>
621
622  <x:ref>extension-code</x:ref> = 3<x:ref>DIGIT</x:ref>
623  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
624</artwork></figure>
625<t>
626   HTTP status codes are extensible. HTTP applications are not required
627   to understand the meaning of all registered status codes, though such
628   understanding is obviously desirable. However, applications &MUST;
629   understand the class of any status code, as indicated by the first
630   digit, and treat any unrecognized response as being equivalent to the
631   x00 status code of that class, with the exception that an
632   unrecognized response &MUST-NOT; be cached. For example, if an
633   unrecognized status code of 431 is received by the client, it can
634   safely assume that there was something wrong with its request and
635   treat the response as if it had received a 400 status code. In such
636   cases, user agents &SHOULD; present to the user the representation enclosed
637   with the response, since that representation is likely to include human-readable
638   information which will explain the unusual status.
639</t>
640
641<section title="Status Code Registry" anchor="status.code.registry">
642<t>
643  The HTTP Status Code Registry defines the name space for the Status-Code
644  token in the Status-Line of an HTTP response.
645</t>
646<t>
647  Values to be added to this name space are subject to IETF review
648  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
649</t>
650<t>
651  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
652</t>
653
654<section title="Considerations for New Status Codes" anchor="considerations.for.new.status.codes">
655<t>
656   When it is necessary to express new semantics for a HTTP response that
657   aren't specific to a single application or media type, and currently defined
658   status codes are inadequate, a new status code can be registered.
659</t>
660<t>
661   HTTP status codes are generic; that is, they are potentially applicable to
662   any resource, not just one particular media type, "type" of resource, or
663   application. As such, it is preferred that new HTTP status codes be
664   registered in a document that isn't specific to a single application, so
665   that this is clear.
666</t>
667<t>
668   Definitions of new HTTP status codes typically explain the request
669   conditions that produce a response containing the status code (e.g.,
670   combinations of request headers and/or method(s)), along with any
671   interactions with response headers (e.g., those that are required, those
672   that modify the semantics of the response).
673</t>
674<t>
675   New HTTP status codes are required to fall under one of the categories
676   defined in <xref target="status.codes"/>. To allow existing parsers to
677   properly handle them, new status codes cannot disallow a response body,
678   although they can mandate a zero-length response body. They can require the
679   presence of one or more particular HTTP response header(s).
680</t>
681<t>
682   Likewise, their definitions can specify that caches are allowed to use
683   heuristics to determine their freshness (see &caching;; by default, it is
684   not allowed), and can define how to determine the resource which they
685   carry a representation for (see <xref
686   target="identifying.response.associated.with.representation"/>; by default,
687   it is anonymous).
688</t>
689</section>
690
691</section>
692
693</section>
694
695<section title="Response Header Fields" anchor="response.header.fields">
696  <x:anchor-alias value="response-header"/>
697<t>
698   The response-header fields allow the server to pass additional
699   information about the response which cannot be placed in the Status-Line.
700   These header fields give information about the server and about
701   further access to the target resource (&effective-request-uri;).
702</t>
703<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="response-header"/>
704  <x:ref>response-header</x:ref> = <x:ref>Accept-Ranges</x:ref>           ; &header-accept-ranges;
705                  / <x:ref>Age</x:ref>                     ; &header-age;
706                  / <x:ref>Allow</x:ref>                   ; <xref target="header.allow"/>
707                  / <x:ref>ETag</x:ref>                    ; &header-etag;
708                  / <x:ref>Location</x:ref>                ; <xref target="header.location"/>
709                  / <x:ref>Proxy-Authenticate</x:ref>      ; &header-proxy-authenticate;
710                  / <x:ref>Retry-After</x:ref>             ; <xref target="header.retry-after"/>
711                  / <x:ref>Server</x:ref>                  ; <xref target="header.server"/>
712                  / <x:ref>Vary</x:ref>                    ; &header-vary;
713                  / <x:ref>WWW-Authenticate</x:ref>        ; &header-www-authenticate;
714</artwork></figure>
715<t>
716   Response-header field names can be extended reliably only in
717   combination with a change in the protocol version. However, new or
718   experimental header fields &MAY; be given the semantics of response-header
719   fields if all parties in the communication recognize them to
720   be response-header fields.
721</t>
722</section>
723
724<section title="Representation" anchor="representation">
725<t>
726   Request and Response messages &MAY; transfer a representation if not otherwise
727   restricted by the request method or response status code. A representation
728   consists of metadata (representation header fields) and data (representation
729   body).  When a complete or partial representation is enclosed in an HTTP message,
730   it is referred to as the payload of the message. HTTP representations
731   are defined in &payload;.
732</t>
733<t>
734   A representation body is only present in a message when a message-body is
735   present, as described in &message-body;. The representation body is obtained
736   from the message-body by decoding any Transfer-Encoding that might
737   have been applied to ensure safe and proper transfer of the message.
738</t>
739
740<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
741<t>
742   It is sometimes necessary to determine an identifier for the resource
743   associated with a representation.
744</t>
745<t>
746   An HTTP request representation, when present, is always associated with an
747   anonymous (i.e., unidentified) resource.
748</t>
749<t>
750   In the common case, an HTTP response is a representation of the target
751   resource (see &effective-request-uri;). However, this is not always the
752   case. To determine the URI of the resource a response is associated with,
753   the following rules are used (with the first applicable one being selected):
754</t>
755<t><list style="numbers">
756   <t>If the response status code is 200 or 203 and the request method was GET,
757   the response payload is a representation of the target resource.</t>
758   <t>If the response status code is 204, 206, or 304 and the request method was GET
759   or HEAD, the response payload is a partial representation of the target
760   (see &combining-responses;).</t>
761   <t>If the response has a Content-Location header field, and that URI is the same
762   as the effective request URI, the response payload is a representation of the
763   target resource.</t>
764   <t>If the response has a Content-Location header field, and that URI is not the
765   same as the effective request URI, then the response asserts that its
766   payload is a representation of the resource identified by the
767   Content-Location URI. However, such an assertion cannot be trusted unless
768   it can be verified by other means (not defined by HTTP).</t>
769   <t>Otherwise, the response is a representation of an anonymous (i.e.,
770   unidentified) resource.</t>
771</list></t>
772<t>
773  <cref anchor="TODO-req-uri">
774   The comparison function is going to have to be defined somewhere,
775   because we already need to compare URIs for things like cache invalidation.</cref>
776</t>
777</section>
778
779</section>
780
781
782<section title="Method Definitions" anchor="method.definitions">
783<t>
784   The set of common methods for HTTP/1.1 is defined below. Although
785   this set can be expanded, additional methods cannot be assumed to
786   share the same semantics for separately extended clients and servers.
787</t>
788
789<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
790
791<section title="Safe Methods" anchor="safe.methods">
792<iref item="Safe Methods" primary="true"/>
793<t>
794   Implementors need to be aware that the software represents the user in
795   their interactions over the Internet, and need to allow
796   the user to be aware of any actions they take which might have an
797   unexpected significance to themselves or others.
798</t>
799<t>
800   In particular, the convention has been established that the GET, HEAD,
801   OPTIONS, and TRACE methods &SHOULD-NOT; have the significance of taking an action
802   other than retrieval. These methods ought to be considered "<x:dfn anchor="safe">safe</x:dfn>".
803   This allows user agents to represent other methods, such as POST, PUT
804   and DELETE, in a special way, so that the user is made aware of the
805   fact that a possibly unsafe action is being requested.
806</t>
807<t>
808   Naturally, it is not possible to ensure that the server does not
809   generate side-effects as a result of performing a GET request; in
810   fact, some dynamic resources consider that a feature. The important
811   distinction here is that the user did not request the side-effects,
812   so therefore cannot be held accountable for them.
813</t>
814</section>
815
816<section title="Idempotent Methods" anchor="idempotent.methods">
817<iref item="Idempotent Methods" primary="true"/>
818<t>
819   Methods can also have the property of "idempotence" in that, aside
820   from error or expiration issues, the intended effect of multiple
821   identical requests is the same as for a single request.
822   The methods PUT, DELETE, and all safe methods are idempotent.
823   It is important to note that idempotence refers only to changes
824   requested by the client: a server is free to change its state due
825   to multiple requests for the purpose of tracking those requests,
826   versioning of results, etc.
827</t>
828</section>
829</section>
830
831<section title="OPTIONS" anchor="OPTIONS">
832  <rdf:Description>
833    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
834  </rdf:Description>
835  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
836  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
837<t>
838   The OPTIONS method represents a request for information about the
839   communication options available on the request/response chain
840   identified by the effective request URI. This method allows the client to
841   determine the options and/or requirements associated with a resource,
842   or the capabilities of a server, without implying a resource action
843   or initiating a resource retrieval.
844</t>
845<t>
846   Responses to this method are not cacheable.
847</t>
848<t>
849   If the OPTIONS request includes a message-body (as indicated by the
850   presence of Content-Length or Transfer-Encoding), then the media type
851   &MUST; be indicated by a Content-Type field. Although this
852   specification does not define any use for such a body, future
853   extensions to HTTP might use the OPTIONS body to make more detailed
854   queries on the server.
855</t>
856<t>
857   If the request-target is an asterisk ("*"), the OPTIONS request is
858   intended to apply to the server in general rather than to a specific
859   resource. Since a server's communication options typically depend on
860   the resource, the "*" request is only useful as a "ping" or "no-op"
861   type of method; it does nothing beyond allowing the client to test
862   the capabilities of the server. For example, this can be used to test
863   a proxy for HTTP/1.1 compliance (or lack thereof).
864</t>
865<t>
866   If the request-target is not an asterisk, the OPTIONS request applies
867   only to the options that are available when communicating with that
868   resource.
869</t>
870<t>
871   A 200 response &SHOULD; include any header fields that indicate
872   optional features implemented by the server and applicable to that
873   resource (e.g., Allow), possibly including extensions not defined by
874   this specification. The response body, if any, &SHOULD; also include
875   information about the communication options. The format for such a
876   body is not defined by this specification, but might be defined by
877   future extensions to HTTP. Content negotiation &MAY; be used to select
878   the appropriate response format. If no response body is included, the
879   response &MUST; include a Content-Length field with a field-value of
880   "0".
881</t>
882<t>
883   The Max-Forwards request-header field &MAY; be used to target a
884   specific proxy in the request chain (see <xref target="header.max-forwards"/>).
885   If no Max-Forwards field is present in the request, then the forwarded
886   request &MUST-NOT; include a Max-Forwards field.
887</t>
888</section>
889
890<section title="GET" anchor="GET">
891  <rdf:Description>
892    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
893  </rdf:Description>
894  <iref primary="true" item="GET method" x:for-anchor=""/>
895  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
896<t>
897   The GET method means retrieve whatever information (in the form of a
898   representation) currently corresponds to the target resource.
899</t>
900<t>   
901   If the target resource is a data-producing process, it is the
902   produced data which shall be returned as the representation in the response and not
903   the source text of the process, unless that text happens to be the output of
904   the process.
905</t>
906<t>
907   The semantics of the GET method change to a "conditional GET" if the
908   request message includes an If-Modified-Since, If-Unmodified-Since,
909   If-Match, If-None-Match, or If-Range header field. A conditional GET
910   method requests that the representation be transferred only under the
911   circumstances described by the conditional header field(s). The
912   conditional GET method is intended to reduce unnecessary network
913   usage by allowing cached representations to be refreshed without requiring
914   multiple requests or transferring data already held by the client.
915</t>
916<t>
917   The semantics of the GET method change to a "partial GET" if the
918   request message includes a Range header field. A partial GET requests
919   that only part of the representation be transferred, as described in &header-range;.
920   The partial GET method is intended to reduce unnecessary
921   network usage by allowing partially-retrieved representations to be
922   completed without transferring data already held by the client.
923</t>
924<t>
925   The response to a GET request is cacheable and &MAY; be used to satisfy
926   subsequent GET and HEAD requests (see &caching;).
927</t>
928<t>
929   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
930</t>
931</section>
932
933<section title="HEAD" anchor="HEAD">
934  <rdf:Description>
935    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
936  </rdf:Description>
937  <iref primary="true" item="HEAD method" x:for-anchor=""/>
938  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
939<t>
940   The HEAD method is identical to GET except that the server &MUST-NOT;
941   return a message-body in the response. The metadata contained
942   in the HTTP header fields in response to a HEAD request &SHOULD; be identical
943   to the information sent in response to a GET request. This method can
944   be used for obtaining metadata about the representation implied by the
945   request without transferring the representation body. This method is
946   often used for testing hypertext links for validity, accessibility,
947   and recent modification.
948</t>
949<t>
950   The response to a HEAD request is cacheable and &MAY; be used to satisfy
951   a subsequent HEAD request; see &caching;. It also &MAY; be used to update a previously cached
952   representation from that resource; if the new field values
953   indicate that the cached representation differs from the current representation (as
954   would be indicated by a change in Content-Length, Content-MD5, ETag
955   or Last-Modified), then the cache &MUST; treat the cache entry as
956   stale.
957</t>
958</section>
959
960<section title="POST" anchor="POST">
961  <iref primary="true" item="POST method" x:for-anchor=""/>
962  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
963<t>
964   The POST method is used to request that the origin server accept the
965   representation enclosed in the request as data to be processed by the
966   target resource. POST is designed to allow a uniform method to cover the
967   following functions:
968  <list style="symbols">
969    <t>
970      Annotation of existing resources;
971    </t>
972    <t>
973        Posting a message to a bulletin board, newsgroup, mailing list,
974        or similar group of articles;
975    </t>
976    <t>
977        Providing a block of data, such as the result of submitting a
978        form, to a data-handling process;
979    </t>
980    <t>
981        Extending a database through an append operation.
982    </t>
983  </list>
984</t>
985<t>
986   The actual function performed by the POST method is determined by the
987   server and is usually dependent on the effective request URI.
988</t>
989<t>
990   The action performed by the POST method might not result in a
991   resource that can be identified by a URI. In this case, either 200
992   (OK) or 204 (No Content) is the appropriate response status code,
993   depending on whether or not the response includes a representation that
994   describes the result.
995</t>
996<t>
997   If a resource has been created on the origin server, the response
998   &SHOULD; be 201 (Created) and contain a representation which describes the
999   status of the request and refers to the new resource, and a Location
1000   header field (see <xref target="header.location"/>).
1001</t>
1002<t>
1003   Responses to POST requests are only cacheable when they
1004   include explicit freshness information (see &p6-explicit;). A
1005   cached POST response with a Content-Location header field
1006   (see &header-content-location;) whose value is the effective
1007   Request URI &MAY; be used to satisfy subsequent GET and HEAD requests.
1008</t>
1009<t>
1010   Note that POST caching is not widely implemented.
1011   However, the 303 (See Other) response can be used to direct the
1012   user agent to retrieve a cacheable resource.
1013</t>
1014</section>
1015
1016<section title="PUT" anchor="PUT">
1017  <iref primary="true" item="PUT method" x:for-anchor=""/>
1018  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
1019<t>
1020   The PUT method requests that the enclosed representation be stored at the
1021   effective request URI. If the effective request URI refers to an already
1022   existing resource, the enclosed representation &SHOULD; be considered a
1023   modified version of the one residing on the origin server. Otherwise, if the
1024   effective request URI does not point to an existing resource, and that URI is
1025   capable of being defined as a new resource by the requesting user
1026   agent, the origin server can create the resource with that URI.
1027</t>
1028<t>   
1029   If a new resource is created at the effective request URI, the origin
1030   server &MUST; inform the user agent
1031   via the 201 (Created) response. If an existing resource is modified,
1032   either the 200 (OK) or 204 (No Content) response codes &SHOULD; be sent
1033   to indicate successful completion of the request.
1034</t>
1035<t>   
1036   If the target resource could not be created or modified, an appropriate
1037   error response &SHOULD; be given that reflects the nature of the problem.
1038   The recipient of the representation &MUST-NOT; ignore any Content-*
1039   header fields (headers starting with the prefix "Content-") that it does
1040   not understand or implement
1041   and &MUST; return a 501 (Not Implemented) response in such cases.
1042</t>
1043<t>
1044   If the request passes through a cache that has one or more stored
1045   responses for the effective request URI, those stored responses
1046   &SHOULD; be marked as stale if the response to the PUT request
1047   has a success status code. Responses to the PUT method are
1048   not cacheable.
1049</t>
1050<t>
1051   The fundamental difference between the POST and PUT requests is
1052   reflected in the different meaning of the effective request URI. The URI in a
1053   POST request identifies the resource that will handle the enclosed
1054   representation. That resource might be a data-accepting process, a gateway to
1055   some other protocol, or a document that accepts annotations.
1056   In contrast, the URI in a PUT request identifies the resource for
1057   which enclosed representation is a new or replacement value; the
1058   user agent knows what URI is intended and the server &MUST-NOT; attempt
1059   to apply the request to some other resource.
1060   If the server desires that the request be applied to a different URI,
1061   it &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
1062   then make its own decision regarding whether or not to redirect the
1063   request.
1064</t>
1065<t>
1066   A single resource &MAY; be identified by many different URIs. For
1067   example, an article might have a URI for identifying "the current
1068   version" which is separate from the URI identifying each particular
1069   version. In this case, a PUT request on a general URI might result in
1070   several other URIs being defined by the origin server.
1071</t>
1072<t>
1073   HTTP/1.1 does not define how a PUT method affects the state of an
1074   origin server.
1075</t>
1076<t>
1077   Header fields in a PUT request that are recognized as representation
1078   metadata &SHOULD; be applied to the resource created or modified by
1079   the PUT.  Unrecognized header fields &SHOULD; be ignored.
1080</t>
1081</section>
1082
1083<section title="DELETE" anchor="DELETE">
1084  <iref primary="true" item="DELETE method" x:for-anchor=""/>
1085  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
1086<t>
1087   The DELETE method requests that the origin server delete the target
1088   resource. This method &MAY; be overridden by
1089   human intervention (or other means) on the origin server. The client cannot
1090   be guaranteed that the operation has been carried out, even if the
1091   status code returned from the origin server indicates that the action
1092   has been completed successfully. However, the server &SHOULD-NOT; 
1093   indicate success unless, at the time the response is given, it
1094   intends to delete the resource or move it to an inaccessible
1095   location.
1096</t>
1097<t>
1098   A successful response &SHOULD; be 200 (OK) if the response includes an
1099   representation describing the status, 202 (Accepted) if the action has not
1100   yet been enacted, or 204 (No Content) if the action has been enacted
1101   but the response does not include a representation.
1102</t>
1103<t>
1104   If the request passes through a cache and the effective request URI
1105   identifies one or more currently cached representations, those entries &SHOULD; be
1106   treated as stale. Responses to the DELETE method are not cacheable.
1107</t>
1108</section>
1109
1110<section title="TRACE" anchor="TRACE">
1111  <rdf:Description>
1112    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1113  </rdf:Description>
1114  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1115  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1116<t>
1117   The TRACE method is used to invoke a remote, application-layer loop-back
1118   of the request message. The final recipient of the request
1119   &SHOULD; reflect the message received back to the client as the
1120   message-body of a 200 (OK) response. The final recipient is either the
1121   origin server or the first proxy or gateway to receive a Max-Forwards
1122   value of zero (0) in the request (see <xref target="header.max-forwards"/>).
1123   A TRACE request &MUST-NOT; include a message-body.
1124</t>
1125<t>
1126   TRACE allows the client to see what is being received at the other
1127   end of the request chain and use that data for testing or diagnostic
1128   information. The value of the Via header field (&header-via;) is of
1129   particular interest, since it acts as a trace of the request chain.
1130   Use of the Max-Forwards header field allows the client to limit the
1131   length of the request chain, which is useful for testing a chain of
1132   proxies forwarding messages in an infinite loop.
1133</t>
1134<t>
1135   If the request is valid, the response &SHOULD; have a Content-Type of
1136   "message/http" (see &media-type-message-http;) and contain a message-body
1137   that encloses a copy of the entire request message.
1138   Responses to the TRACE method are not cacheable.
1139</t>
1140</section>
1141
1142<section title="CONNECT" anchor="CONNECT">
1143  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1144  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1145<t>
1146   The CONNECT method is used with a proxy to dynamically switch
1147   the connection to a tunnel.
1148</t>
1149<t>
1150   When using CONNECT, the request-target &MUST; be use the authority form
1151   (&request-target;); i.e., the host name and port number destination of the
1152   requested connection separated by a colon:
1153</t>
1154<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1155CONNECT server.example.com:80 HTTP/1.1
1156Host: server.example.com:80
1157
1158</artwork></figure>
1159<t>
1160   Other HTTP mechanisms can be used normally with the CONNECT method --
1161   except end-to-end protocol Upgrade requests, since the
1162   tunnel must be established first.
1163</t>
1164<t>
1165   For example, proxy authentication might be used to establish the
1166   authority to create a tunnel:
1167</t>
1168<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1169CONNECT server.example.com:80 HTTP/1.1
1170Host: server.example.com:80
1171Proxy-Authorization: basic aGVsbG86d29ybGQ=
1172
1173</artwork></figure>
1174<t>
1175   Like any other pipelined HTTP/1.1 request, data to be tunnel may be
1176   sent immediately after the blank line. The usual caveats also apply:
1177   data may be discarded if the eventual response is negative, and the
1178   connection may be reset with no response if more than one TCP segment
1179   is outstanding.
1180</t>
1181
1182<section title="Establishing a Tunnel with CONNECT">
1183<t>
1184   Any successful (2xx) response to a CONNECT request indicates that the
1185   proxy has established a connection to the requested host and port,
1186   and has switched to tunneling the current connection to that server
1187   connection.
1188</t>
1189<t>
1190   It may be the case that the proxy itself can only reach the requested
1191   origin server through another proxy.  In this case, the first proxy
1192   &SHOULD; make a CONNECT request of that next proxy, requesting a tunnel
1193   to the authority.  A proxy &MUST-NOT; respond with any 2xx status code
1194   unless it has either a direct or tunnel connection established to the
1195   authority.
1196</t>
1197<t>
1198   An origin server which receives a CONNECT request for itself &MAY;
1199   respond with a 2xx status code to indicate that a connection is
1200   established.
1201</t>
1202<t>
1203   If at any point either one of the peers gets disconnected, any
1204   outstanding data that came from that peer will be passed to the other
1205   one, and after that also the other connection will be terminated by
1206   the proxy. If there is outstanding data to that peer undelivered,
1207   that data will be discarded.
1208</t>
1209
1210</section>
1211</section>
1212</section>
1213
1214
1215<section title="Status Code Definitions" anchor="status.codes">
1216<t>
1217   Each Status-Code is described below, including any metadata required
1218   in the response.
1219</t>
1220
1221<section title="Informational 1xx" anchor="status.1xx">
1222<t>
1223   This class of status code indicates a provisional response,
1224   consisting only of the Status-Line and optional header fields, and is
1225   terminated by an empty line. There are no required header fields for this
1226   class of status code. Since HTTP/1.0 did not define any 1xx status
1227   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1228   except under experimental conditions.
1229</t>
1230<t>
1231   A client &MUST; be prepared to accept one or more 1xx status responses
1232   prior to a regular response, even if the client does not expect a 100
1233   (Continue) status message. Unexpected 1xx status responses &MAY; be
1234   ignored by a user agent.
1235</t>
1236<t>
1237   Proxies &MUST; forward 1xx responses, unless the connection between the
1238   proxy and its client has been closed, or unless the proxy itself
1239   requested the generation of the 1xx response. (For example, if a
1240   proxy adds a "Expect: 100-continue" field when it forwards a request,
1241   then it need not forward the corresponding 100 (Continue)
1242   response(s).)
1243</t>
1244
1245<section title="100 Continue" anchor="status.100">
1246  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1247  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1248<t>
1249   The client &SHOULD; continue with its request. This interim response is
1250   used to inform the client that the initial part of the request has
1251   been received and has not yet been rejected by the server. The client
1252   &SHOULD; continue by sending the remainder of the request or, if the
1253   request has already been completed, ignore this response. The server
1254   &MUST; send a final response after the request has been completed. See
1255   &use100; for detailed discussion of the use and handling of this
1256   status code.
1257</t>
1258</section>
1259
1260<section title="101 Switching Protocols" anchor="status.101">
1261  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1262  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1263<t>
1264   The server understands and is willing to comply with the client's
1265   request, via the Upgrade message header field (&header-upgrade;), for a
1266   change in the application protocol being used on this connection. The
1267   server will switch protocols to those defined by the response's
1268   Upgrade header field immediately after the empty line which
1269   terminates the 101 response.
1270</t>
1271<t>
1272   The protocol &SHOULD; be switched only when it is advantageous to do
1273   so. For example, switching to a newer version of HTTP is advantageous
1274   over older versions, and switching to a real-time, synchronous
1275   protocol might be advantageous when delivering resources that use
1276   such features.
1277</t>
1278</section>
1279</section>
1280
1281<section title="Successful 2xx" anchor="status.2xx">
1282<t>
1283   This class of status code indicates that the client's request was
1284   successfully received, understood, and accepted.
1285</t>
1286
1287<section title="200 OK" anchor="status.200">
1288  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1289  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1290<t>
1291   The request has succeeded. The payload returned with the response
1292   is dependent on the method used in the request, for example:
1293  <list style="hanging">
1294    <t hangText="GET">
1295          a representation of the target resource is sent in the response;
1296    </t>
1297    <t hangText="HEAD">
1298          the same representation as GET, except without the message-body;
1299    </t>
1300    <t hangText="POST">
1301      a representation describing or containing the result of the action;
1302    </t>
1303    <t hangText="TRACE">
1304      a representation containing the request message as received by the
1305      end server.
1306    </t>
1307  </list>
1308</t>
1309<t>
1310   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1311   freshness for 200 responses.
1312</t>
1313</section>
1314
1315<section title="201 Created" anchor="status.201">
1316  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1317  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1318<t>
1319   The request has been fulfilled and has resulted in a new resource being
1320   created. The newly created resource can be referenced by the URI(s)
1321   returned in the payload of the response, with the most specific URI
1322   for the resource given by a Location header field. The response
1323   &SHOULD; include a payload containing a list of resource
1324   characteristics and location(s) from which the user or user agent can
1325   choose the one most appropriate. The payload format is specified by
1326   the media type given in the Content-Type header field. The origin
1327   server &MUST; create the resource before returning the 201 status code.
1328   If the action cannot be carried out immediately, the server &SHOULD;
1329   respond with 202 (Accepted) response instead.
1330</t>
1331<t>
1332   A 201 response &MAY; contain an ETag response header field indicating
1333   the current value of the entity-tag for the representation of the resource
1334   just created (see &header-etag;).
1335</t>
1336</section>
1337
1338<section title="202 Accepted" anchor="status.202">
1339  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1340  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1341<t>
1342   The request has been accepted for processing, but the processing has
1343   not been completed.  The request might or might not eventually be
1344   acted upon, as it might be disallowed when processing actually takes
1345   place. There is no facility for re-sending a status code from an
1346   asynchronous operation such as this.
1347</t>
1348<t>
1349   The 202 response is intentionally non-committal. Its purpose is to
1350   allow a server to accept a request for some other process (perhaps a
1351   batch-oriented process that is only run once per day) without
1352   requiring that the user agent's connection to the server persist
1353   until the process is completed. The representation returned with this
1354   response &SHOULD; include an indication of the request's current status
1355   and either a pointer to a status monitor or some estimate of when the
1356   user can expect the request to be fulfilled.
1357</t>
1358</section>
1359
1360<section title="203 Non-Authoritative Information" anchor="status.203">
1361  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1362  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1363<t>
1364   The returned metadata in the header fields is not the
1365   definitive set as available from the origin server, but is gathered
1366   from a local or a third-party copy. The set presented &MAY; be a subset
1367   or superset of the original version. For example, including local
1368   annotation information about the resource might result in a superset
1369   of the metadata known by the origin server. Use of this
1370   response code is not required and is only appropriate when the
1371   response would otherwise be 200 (OK).
1372</t>
1373<t>
1374   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1375   freshness for 203 responses.
1376</t>
1377
1378</section>
1379
1380<section title="204 No Content" anchor="status.204">
1381  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1382  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1383<t>
1384   The server has successfully fulfilled the request, but there is no
1385   additional content to return in the response payload body.  The
1386   resource metadata and representation metadata in the response message's
1387   header fields refer to the target resource
1388   and its current representation, respectively, after the requested action.
1389   For example, if a 204 status code is received in response to a PUT
1390   and the response contains an ETag header field, then the value of
1391   that field is the current entity-tag for the representation that
1392   was successfully PUT.
1393</t>
1394<t>
1395   If the client is a user agent, it &SHOULD-NOT; change its document view
1396   from that which caused the request to be sent. This response is
1397   primarily intended to allow input for actions to take place without
1398   causing a change to the user agent's active document view, although
1399   any new or updated metadata &SHOULD; be applied to the document
1400   currently in the user agent's active view.
1401</t>
1402<t>
1403   The 204 response &MUST-NOT; include a message-body, and thus is always
1404   terminated by the first empty line after the header fields.
1405</t>
1406</section>
1407
1408<section title="205 Reset Content" anchor="status.205">
1409  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1410  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1411<t>
1412   The server has fulfilled the request and the user agent &SHOULD; reset
1413   the document view which caused the request to be sent. This response
1414   is primarily intended to allow input for actions to take place via
1415   user input, followed by a clearing of the form in which the input is
1416   given so that the user can easily initiate another input action.
1417</t>
1418<t>   
1419   The message-body included with the response &MUST; be empty. Note that
1420   receivers still need to parse the response according to the algorithm defined
1421   in &message-body;.
1422</t>
1423</section>
1424
1425<section title="206 Partial Content" anchor="status.206">
1426  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1427  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1428  <rdf:Description>
1429    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1430  </rdf:Description>
1431<t>
1432   The server has fulfilled the partial GET request for the resource
1433   and the enclosed payload is a partial representation as defined in &status-206;.
1434</t>
1435<t>
1436   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1437   freshness for 206 responses.
1438</t>
1439</section>
1440</section>
1441
1442<section title="Redirection 3xx" anchor="status.3xx">
1443<t>
1444   This class of status code indicates that further action needs to be
1445   taken by the user agent in order to fulfill the request.  The action
1446   required &MAY; be carried out by the user agent without interaction
1447   with the user if and only if the method used in the second request is
1448   known to be "safe", as defined in <xref target="safe.methods"/>.
1449   A client &SHOULD; detect infinite redirection loops, since such loops
1450   generate network traffic for each redirection.
1451</t>
1452<x:note>
1453  <t>
1454    <x:h>Note:</x:h> An earlier version of this specification recommended a
1455    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1456    Content developers need to be aware that some clients might
1457    implement such a fixed limitation.
1458  </t>
1459</x:note>
1460
1461<section title="300 Multiple Choices" anchor="status.300">
1462  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1463  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1464<t>
1465   The target resource has more than one
1466   representation, each with its own specific location, and agent-driven
1467   negotiation information (&content-negotiation;) is being provided so that
1468   the user (or user agent) can select a preferred representation by
1469   redirecting its request to that location.
1470</t>
1471<t>
1472   Unless it was a HEAD request, the response &SHOULD; include a representation
1473   containing a list of representation metadata and location(s) from
1474   which the user or user agent can choose the one most appropriate. The
1475   data format is specified by the media type given in the Content-Type
1476   header field. Depending upon the format and the capabilities of
1477   the user agent, selection of the most appropriate choice &MAY; be
1478   performed automatically. However, this specification does not define
1479   any standard for such automatic selection.
1480</t>
1481<t>
1482   If the server has a preferred choice of representation, it &SHOULD;
1483   include the specific URI for that representation in the Location
1484   field; user agents &MAY; use the Location field value for automatic
1485   redirection.
1486</t>
1487<t>
1488   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1489   freshness for 300 responses.
1490</t>
1491
1492</section>
1493
1494<section title="301 Moved Permanently" anchor="status.301">
1495  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1496  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1497<t>
1498   The target resource has been assigned a new permanent URI and any
1499   future references to this resource &SHOULD; use one of the returned
1500   URIs.  Clients with link editing capabilities ought to automatically
1501   re-link references to the effective request URI to one or more of the new
1502   references returned by the server, where possible.
1503</t>
1504<t>
1505   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1506   freshness for 301 responses.
1507</t>
1508<t>
1509   The new permanent URI &SHOULD; be given by the Location field in the
1510   response. Unless the request method was HEAD, the representation of the
1511   response &SHOULD; contain a short hypertext note with a hyperlink to
1512   the new URI(s).
1513</t>
1514<t>
1515   If the 301 status code is received in response to a request method
1516   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1517   then the request &MAY; be automatically redirected by the user agent without
1518   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1519   request unless it can be confirmed by the user, since this might
1520   change the conditions under which the request was issued.
1521</t>
1522<x:note>
1523  <t>
1524    <x:h>Note:</x:h> When automatically redirecting a POST request after
1525    receiving a 301 status code, some existing HTTP/1.0 user agents
1526    will erroneously change it into a GET request.
1527  </t>
1528</x:note>
1529</section>
1530
1531<section title="302 Found" anchor="status.302">
1532  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1533  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1534<t>
1535   The target resource resides temporarily under a different URI.
1536   Since the redirection might be altered on occasion, the client &SHOULD;
1537   continue to use the effective request URI for future requests.
1538</t>
1539<t>
1540   The temporary URI &SHOULD; be given by the Location field in the
1541   response. Unless the request method was HEAD, the representation of the
1542   response &SHOULD; contain a short hypertext note with a hyperlink to
1543   the new URI(s).
1544</t>
1545<t>
1546   If the 302 status code is received in response to a request method
1547   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1548   then the request &MAY; be automatically redirected by the user agent without
1549   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1550   request unless it can be confirmed by the user, since this might
1551   change the conditions under which the request was issued.
1552</t>
1553<x:note>
1554  <t>
1555    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1556    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1557    specify that the client is not allowed to change the method on the
1558    redirected request.  However, most existing user agent implementations
1559    treat 302 as if it were a 303 response, performing a GET on the Location
1560    field-value regardless of the original request method. Therefore, a
1561    previous version of this specification
1562    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1563    status codes
1564    <xref target="status.303" format="none">303</xref> and
1565    <xref target="status.307" format="none">307</xref> for servers that wish
1566    to make unambiguously clear which kind of reaction is expected of the
1567    client.
1568  </t>
1569</x:note>
1570</section>
1571
1572<section title="303 See Other" anchor="status.303">
1573  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1574  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1575<t>
1576   The server directs the user agent to a different resource, indicated
1577   by a URI in the Location header field, that provides an indirect
1578   response to the original request.  The user agent &MAY; perform a GET
1579   request on the URI in the Location field in order to obtain a
1580   representation corresponding to the response, be redirected again,
1581   or end with an error status.  The Location URI is not a substitute
1582   reference for the effective request URI.
1583</t>
1584<t>
1585   The 303 status code is generally applicable to any HTTP method.  It is
1586   primarily used to allow the output of a POST action to redirect
1587   the user agent to a selected resource, since doing so provides the
1588   information corresponding to the POST response in a form that
1589   can be separately identified, bookmarked, and cached independent
1590   of the original request.
1591</t>
1592<t>
1593   A 303 response to a GET request indicates that the requested
1594   resource does not have a representation of its own that can be
1595   transferred by the server over HTTP.  The Location URI indicates a
1596   resource that is descriptive of the target resource, such that the
1597   follow-on representation might be useful to recipients without
1598   implying that it adequately represents the target resource.
1599   Note that answers to the questions of what can be represented, what
1600   representations are adequate, and what might be a useful description
1601   are outside the scope of HTTP and thus entirely determined by the
1602   URI owner(s).
1603</t>
1604<t>
1605   Except for responses to a HEAD request, the representation of a 303
1606   response &SHOULD; contain a short hypertext note with a hyperlink
1607   to the Location URI.
1608</t>
1609</section>
1610
1611<section title="304 Not Modified" anchor="status.304">
1612  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1613  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1614  <rdf:Description>
1615    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1616  </rdf:Description>
1617<t>
1618   The response to the request has not been modified since the conditions
1619   indicated by the client's conditional GET request, as defined in &status-304;.
1620</t>
1621</section>
1622
1623<section title="305 Use Proxy" anchor="status.305">
1624  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1625  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1626<t>
1627   The 305 status code was defined in a previous version of this specification
1628   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1629</t>
1630</section>
1631
1632<section title="306 (Unused)" anchor="status.306">
1633  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1634  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1635<t>
1636   The 306 status code was used in a previous version of the
1637   specification, is no longer used, and the code is reserved.
1638</t>
1639</section>
1640
1641<section title="307 Temporary Redirect" anchor="status.307">
1642  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1643  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1644<t>
1645   The target resource resides temporarily under a different URI.
1646   Since the redirection can change over time, the client &SHOULD;
1647   continue to use the effective request URI for future requests.
1648</t>
1649<t>
1650   The temporary URI &SHOULD; be given by the Location field in the
1651   response. Unless the request method was HEAD, the representation of the
1652   response &SHOULD; contain a short hypertext note with a hyperlink to
1653   the new URI(s), since many pre-HTTP/1.1 user agents do not
1654   understand the 307 status code. Therefore, the note &SHOULD; contain the
1655   information necessary for a user to repeat the original request on
1656   the new URI.
1657</t>
1658<t>
1659   If the 307 status code is received in response to a request method
1660   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1661   then the request &MAY; be automatically redirected by the user agent without
1662   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1663   request unless it can be confirmed by the user, since this might
1664   change the conditions under which the request was issued.
1665</t>
1666</section>
1667</section>
1668
1669<section title="Client Error 4xx" anchor="status.4xx">
1670<t>
1671   The 4xx class of status code is intended for cases in which the
1672   client seems to have erred. Except when responding to a HEAD request,
1673   the server &SHOULD; include a representation containing an explanation of the
1674   error situation, and whether it is a temporary or permanent
1675   condition. These status codes are applicable to any request method.
1676   User agents &SHOULD; display any included representation to the user.
1677</t>
1678<t>
1679   If the client is sending data, a server implementation using TCP
1680   &SHOULD; be careful to ensure that the client acknowledges receipt of
1681   the packet(s) containing the response, before the server closes the
1682   input connection. If the client continues sending data to the server
1683   after the close, the server's TCP stack will send a reset packet to
1684   the client, which might erase the client's unacknowledged input buffers
1685   before they can be read and interpreted by the HTTP application.
1686</t>
1687
1688<section title="400 Bad Request" anchor="status.400">
1689  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1690  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1691<t>
1692   The request could not be understood by the server due to malformed
1693   syntax. The client &SHOULD-NOT; repeat the request without
1694   modifications.
1695</t>
1696</section>
1697
1698<section title="401 Unauthorized" anchor="status.401">
1699  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1700  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1701  <rdf:Description>
1702    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part7</redirects-to>
1703  </rdf:Description>
1704<t>
1705   The request requires user authentication (see &status-401;).
1706</t>
1707</section>
1708
1709<section title="402 Payment Required" anchor="status.402">
1710  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1711  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1712<t>
1713   This code is reserved for future use.
1714</t>
1715</section>
1716
1717<section title="403 Forbidden" anchor="status.403">
1718  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1719  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1720<t>
1721   The server understood the request, but is refusing to fulfill it.
1722   Authorization will not help and the request &SHOULD-NOT;  be repeated.
1723   If the request method was not HEAD and the server wishes to make
1724   public why the request has not been fulfilled, it &SHOULD; describe the
1725   reason for the refusal in the representation.  If the server does not wish to
1726   make this information available to the client, the status code 404
1727   (Not Found) can be used instead.
1728</t>
1729</section>
1730
1731<section title="404 Not Found" anchor="status.404">
1732  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1733  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1734<t>
1735   The server has not found anything matching the effective request URI. No
1736   indication is given of whether the condition is temporary or
1737   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1738   knows, through some internally configurable mechanism, that an old
1739   resource is permanently unavailable and has no forwarding address.
1740   This status code is commonly used when the server does not wish to
1741   reveal exactly why the request has been refused, or when no other
1742   response is applicable.
1743</t>
1744</section>
1745
1746<section title="405 Method Not Allowed" anchor="status.405">
1747  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1748  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1749<t>
1750   The method specified in the Request-Line is not allowed for the target
1751   resource. The response &MUST; include an
1752   Allow header field containing a list of valid methods for the requested
1753   resource.
1754</t>
1755</section>
1756
1757<section title="406 Not Acceptable" anchor="status.406">
1758  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1759  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1760<t>
1761   The resource identified by the request is only capable of generating
1762   response representations which have content characteristics not acceptable
1763   according to the accept header fields sent in the request.
1764</t>
1765<t>
1766   Unless it was a HEAD request, the response &SHOULD; include a representation
1767   containing a list of available representation characteristics and location(s)
1768   from which the user or user agent can choose the one most
1769   appropriate. The data format is specified by the media type given
1770   in the Content-Type header field. Depending upon the format and the
1771   capabilities of the user agent, selection of the most appropriate
1772   choice &MAY; be performed automatically. However, this specification
1773   does not define any standard for such automatic selection.
1774</t>
1775<x:note>
1776  <t>
1777    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1778    not acceptable according to the accept header fields sent in the
1779    request. In some cases, this might even be preferable to sending a
1780    406 response. User agents are encouraged to inspect the header fields of
1781    an incoming response to determine if it is acceptable.
1782  </t>
1783</x:note>
1784<t>
1785   If the response could be unacceptable, a user agent &SHOULD;
1786   temporarily stop receipt of more data and query the user for a
1787   decision on further actions.
1788</t>
1789</section>
1790
1791<section title="407 Proxy Authentication Required" anchor="status.407">
1792  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1793  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1794<t>
1795   This code is similar to 401 (Unauthorized), but indicates that the
1796   client must first authenticate itself with the proxy (see &status-407;).
1797</t>
1798</section>
1799
1800<section title="408 Request Timeout" anchor="status.408">
1801  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1802  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1803<t>
1804   The client did not produce a request within the time that the server
1805   was prepared to wait. The client &MAY; repeat the request without
1806   modifications at any later time.
1807</t>
1808</section>
1809
1810<section title="409 Conflict" anchor="status.409">
1811  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1812  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1813<t>
1814   The request could not be completed due to a conflict with the current
1815   state of the resource. This code is only allowed in situations where
1816   it is expected that the user might be able to resolve the conflict
1817   and resubmit the request. The response body &SHOULD; include enough
1818   information for the user to recognize the source of the conflict.
1819   Ideally, the response representation would include enough information for the
1820   user or user agent to fix the problem; however, that might not be
1821   possible and is not required.
1822</t>
1823<t>
1824   Conflicts are most likely to occur in response to a PUT request. For
1825   example, if versioning were being used and the representation being PUT
1826   included changes to a resource which conflict with those made by an
1827   earlier (third-party) request, the server might use the 409 response
1828   to indicate that it can't complete the request. In this case, the
1829   response representation would likely contain a list of the differences
1830   between the two versions in a format defined by the response
1831   Content-Type.
1832</t>
1833</section>
1834
1835<section title="410 Gone" anchor="status.410">
1836  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1837  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1838<t>
1839   The target resource is no longer available at the server and no
1840   forwarding address is known. This condition is expected to be
1841   considered permanent. Clients with link editing capabilities &SHOULD;
1842   delete references to the effective request URI after user approval. If the
1843   server does not know, or has no facility to determine, whether or not
1844   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1845   used instead.
1846</t>
1847<t>
1848   The 410 response is primarily intended to assist the task of web
1849   maintenance by notifying the recipient that the resource is
1850   intentionally unavailable and that the server owners desire that
1851   remote links to that resource be removed. Such an event is common for
1852   limited-time, promotional services and for resources belonging to
1853   individuals no longer working at the server's site. It is not
1854   necessary to mark all permanently unavailable resources as "gone" or
1855   to keep the mark for any length of time -- that is left to the
1856   discretion of the server owner.
1857</t>
1858<t>
1859   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine freshness
1860   for 410 responses.
1861</t>
1862
1863</section>
1864
1865<section title="411 Length Required" anchor="status.411">
1866  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1867  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1868<t>
1869   The server refuses to accept the request without a defined Content-Length.
1870   The client &MAY; repeat the request if it adds a valid
1871   Content-Length header field containing the length of the message-body
1872   in the request message.
1873</t>
1874</section>
1875
1876<section title="412 Precondition Failed" anchor="status.412">
1877  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1878  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1879  <rdf:Description>
1880    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1881  </rdf:Description>
1882<t>
1883   The precondition given in one or more of the request-header fields
1884   evaluated to false when it was tested on the server, as defined in
1885   &status-412;.
1886</t>
1887</section>
1888
1889<section title="413 Request Entity Too Large" anchor="status.413">
1890  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1891  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1892<t>
1893   The server is refusing to process a request because the request
1894   representation is larger than the server is willing or able to process. The
1895   server &MAY; close the connection to prevent the client from continuing
1896   the request.
1897</t>
1898<t>
1899   If the condition is temporary, the server &SHOULD; include a Retry-After
1900   header field to indicate that it is temporary and after what
1901   time the client &MAY; try again.
1902</t>
1903</section>
1904
1905<section title="414 URI Too Long" anchor="status.414">
1906  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1907  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1908<t>
1909   The server is refusing to service the request because the effective request URI
1910   is longer than the server is willing to interpret. This rare
1911   condition is only likely to occur when a client has improperly
1912   converted a POST request to a GET request with long query
1913   information, when the client has descended into a URI "black hole" of
1914   redirection (e.g., a redirected URI prefix that points to a suffix of
1915   itself), or when the server is under attack by a client attempting to
1916   exploit security holes present in some servers using fixed-length
1917   buffers for reading or manipulating the effective request URI.
1918</t>
1919</section>
1920
1921<section title="415 Unsupported Media Type" anchor="status.415">
1922  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1923  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1924<t>
1925   The server is refusing to service the request because the representation of
1926   the request is in a format not supported by the target resource
1927   for the requested method.
1928</t>
1929</section>
1930
1931<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1932  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1933  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1934  <rdf:Description>
1935    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1936  </rdf:Description>
1937<t>
1938   The request included a Range request-header field (&header-range;) and none of
1939   the range-specifier values in this field overlap the current extent
1940   of the selected resource. See &status-416;.
1941</t>
1942</section>
1943
1944<section title="417 Expectation Failed" anchor="status.417">
1945  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
1946  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
1947<t>
1948   The expectation given in an Expect request-header field (see <xref target="header.expect"/>)
1949   could not be met by this server, or, if the server is a proxy,
1950   the server has unambiguous evidence that the request could not be met
1951   by the next-hop server.
1952</t>
1953</section>
1954</section>
1955
1956<section title="Server Error 5xx" anchor="status.5xx">
1957<t>
1958   Response status codes beginning with the digit "5" indicate cases in
1959   which the server is aware that it has erred or is incapable of
1960   performing the request. Except when responding to a HEAD request, the
1961   server &SHOULD; include a representation containing an explanation of the
1962   error situation, and whether it is a temporary or permanent
1963   condition. User agents &SHOULD; display any included representation to the
1964   user. These response codes are applicable to any request method.
1965</t>
1966
1967<section title="500 Internal Server Error" anchor="status.500">
1968  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
1969  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
1970<t>
1971   The server encountered an unexpected condition which prevented it
1972   from fulfilling the request.
1973</t>
1974</section>
1975
1976<section title="501 Not Implemented" anchor="status.501">
1977  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
1978  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
1979<t>
1980   The server does not support the functionality required to fulfill the
1981   request. This is the appropriate response when the server does not
1982   recognize the request method and is not capable of supporting it for
1983   any resource.
1984</t>
1985</section>
1986
1987<section title="502 Bad Gateway" anchor="status.502">
1988  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
1989  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
1990<t>
1991   The server, while acting as a gateway or proxy, received an invalid
1992   response from the upstream server it accessed in attempting to
1993   fulfill the request.
1994</t>
1995</section>
1996
1997<section title="503 Service Unavailable" anchor="status.503">
1998  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
1999  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
2000<t>
2001   The server is currently unable to handle the request due to a
2002   temporary overloading or maintenance of the server. The implication
2003   is that this is a temporary condition which will be alleviated after
2004   some delay. If known, the length of the delay &MAY; be indicated in a
2005   Retry-After header field. If no Retry-After is given, the client &SHOULD;
2006   handle the response as it would for a 500 response.
2007</t>
2008<x:note>
2009  <t>
2010    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
2011    server must use it when becoming overloaded. Some servers might wish
2012    to simply refuse the connection.
2013  </t>
2014</x:note>
2015</section>
2016
2017<section title="504 Gateway Timeout" anchor="status.504">
2018  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
2019  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
2020<t>
2021   The server, while acting as a gateway or proxy, did not receive a
2022   timely response from the upstream server specified by the URI (e.g.,
2023   HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
2024   to access in attempting to complete the request.
2025</t>
2026<x:note>
2027  <t>
2028    <x:h>Note</x:h> to implementors: some deployed proxies are known to
2029    return 400 or 500 when DNS lookups time out.
2030  </t>
2031</x:note>
2032</section>
2033
2034<section title="505 HTTP Version Not Supported" anchor="status.505">
2035  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
2036  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
2037<t>
2038   The server does not support, or refuses to support, the protocol
2039   version that was used in the request message. The server is
2040   indicating that it is unable or unwilling to complete the request
2041   using the same major version as the client, as described in &http-version;,
2042   other than with this error message. The response &SHOULD; contain
2043   a representation describing why that version is not supported and what other
2044   protocols are supported by that server.
2045</t>
2046
2047</section>
2048</section>
2049</section>
2050
2051
2052<section title="Header Field Definitions" anchor="header.fields">
2053<t>
2054   This section defines the syntax and semantics of HTTP/1.1 header fields
2055   related to request and response semantics.
2056</t>
2057
2058<section title="Allow" anchor="header.allow">
2059  <iref primary="true" item="Allow header" x:for-anchor=""/>
2060  <iref primary="true" item="Headers" subitem="Allow" x:for-anchor=""/>
2061  <x:anchor-alias value="Allow"/>
2062  <x:anchor-alias value="Allow-v"/>
2063<t>
2064   The "Allow" response-header field lists the set of methods advertised as
2065   supported by the target resource. The purpose of
2066   this field is strictly to inform the recipient of valid methods
2067   associated with the resource.
2068</t>
2069<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/><iref primary="true" item="Grammar" subitem="Allow-v"/>
2070  <x:ref>Allow</x:ref>   = "Allow" ":" <x:ref>OWS</x:ref> <x:ref>Allow-v</x:ref>
2071  <x:ref>Allow-v</x:ref> = #<x:ref>Method</x:ref>
2072</artwork></figure>
2073<t>
2074      Example of use:
2075</t>
2076<figure><artwork type="example">
2077  Allow: GET, HEAD, PUT
2078</artwork></figure>
2079<t>
2080      The actual set of allowed methods is defined
2081      by the origin server at the time of each request.
2082</t>
2083<t>
2084      A proxy &MUST-NOT; modify the Allow header field even if it does not
2085      understand all the methods specified, since the user agent might
2086      have other means of communicating with the origin server.
2087</t>
2088</section>
2089
2090<section title="Expect" anchor="header.expect">
2091  <iref primary="true" item="Expect header" x:for-anchor=""/>
2092  <iref primary="true" item="Headers" subitem="Expect" x:for-anchor=""/>
2093  <x:anchor-alias value="Expect"/>
2094  <x:anchor-alias value="Expect-v"/>
2095  <x:anchor-alias value="expectation"/>
2096  <x:anchor-alias value="expectation-extension"/>
2097  <x:anchor-alias value="expect-params"/>
2098<t>
2099   The "Expect" request-header field is used to indicate that particular
2100   server behaviors are required by the client.
2101</t>
2102<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"/>
2103  <x:ref>Expect</x:ref>       = "Expect" ":" <x:ref>OWS</x:ref> <x:ref>Expect-v</x:ref>
2104  <x:ref>Expect-v</x:ref>     = 1#<x:ref>expectation</x:ref>
2105 
2106  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
2107  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
2108                           *<x:ref>expect-params</x:ref> ]
2109  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
2110</artwork></figure>
2111<t>
2112   A server that does not understand or is unable to comply with any of
2113   the expectation values in the Expect field of a request &MUST; respond
2114   with appropriate error status code. The server &MUST; respond with a 417
2115   (Expectation Failed) status code if any of the expectations cannot be met
2116   or, if there are other problems with the request, some other 4xx
2117   status code.
2118</t>
2119<t>
2120   This header field is defined with extensible syntax to allow for
2121   future extensions. If a server receives a request containing an
2122   Expect field that includes an expectation-extension that it does not
2123   support, it &MUST; respond with a 417 (Expectation Failed) status code.
2124</t>
2125<t>
2126   Comparison of expectation values is case-insensitive for unquoted
2127   tokens (including the 100-continue token), and is case-sensitive for
2128   quoted-string expectation-extensions.
2129</t>
2130<t>
2131   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
2132   return a 417 (Expectation Failed) status code if it receives a request
2133   with an expectation that it cannot meet. However, the Expect
2134   request-header field itself is end-to-end; it &MUST; be forwarded if the
2135   request is forwarded.
2136</t>
2137<t>
2138   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
2139   Expect header field.
2140</t>
2141<t>
2142   See &use100; for the use of the 100 (Continue) status code.
2143</t>
2144</section>
2145
2146<section title="From" anchor="header.from">
2147  <iref primary="true" item="From header" x:for-anchor=""/>
2148  <iref primary="true" item="Headers" subitem="From" x:for-anchor=""/>
2149  <x:anchor-alias value="From"/>
2150  <x:anchor-alias value="From-v"/>
2151  <x:anchor-alias value="mailbox"/>
2152<t>
2153   The "From" request-header field, if given, &SHOULD; contain an Internet
2154   e-mail address for the human user who controls the requesting user
2155   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
2156   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
2157</t>
2158<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/><iref primary="true" item="Grammar" subitem="From-v"/>
2159  <x:ref>From</x:ref>    = "From" ":" <x:ref>OWS</x:ref> <x:ref>From-v</x:ref>
2160  <x:ref>From-v</x:ref>  = <x:ref>mailbox</x:ref>
2161 
2162  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
2163</artwork></figure>
2164<t>
2165   An example is:
2166</t>
2167<figure><artwork type="example">
2168  From: webmaster@example.org
2169</artwork></figure>
2170<t>
2171   This header field &MAY; be used for logging purposes and as a means for
2172   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
2173   be used as an insecure form of access protection. The interpretation
2174   of this field is that the request is being performed on behalf of the
2175   person given, who accepts responsibility for the method performed. In
2176   particular, robot agents &SHOULD; include this header field so that the
2177   person responsible for running the robot can be contacted if problems
2178   occur on the receiving end.
2179</t>
2180<t>
2181   The Internet e-mail address in this field &MAY; be separate from the
2182   Internet host which issued the request. For example, when a request
2183   is passed through a proxy the original issuer's address &SHOULD; be
2184   used.
2185</t>
2186<t>
2187   The client &SHOULD-NOT;  send the From header field without the user's
2188   approval, as it might conflict with the user's privacy interests or
2189   their site's security policy. It is strongly recommended that the
2190   user be able to disable, enable, and modify the value of this field
2191   at any time prior to a request.
2192</t>
2193</section>
2194
2195<section title="Location" anchor="header.location">
2196  <iref primary="true" item="Location header" x:for-anchor=""/>
2197  <iref primary="true" item="Headers" subitem="Location" x:for-anchor=""/>
2198  <x:anchor-alias value="Location"/>
2199  <x:anchor-alias value="Location-v"/>
2200<t>
2201   The "Location" response-header field is used to identify a newly created
2202   resource, or to redirect the recipient to a different location for
2203   completion of the request.
2204</t>
2205<t>
2206   For 201 (Created) responses, the Location is the URI of the new resource
2207   which was created by the request. For 3xx responses, the location &SHOULD;
2208   indicate the server's preferred URI for automatic redirection to the
2209   resource.
2210</t>
2211<t>
2212   The field value consists of a single URI-reference. When it has the form
2213   of a relative reference (<xref target="RFC3986" x:fmt="," x:sec="4.2"/>),
2214   the final value is computed by resolving it against the effective request
2215   URI (<xref target="RFC3986" x:fmt="," x:sec="5"/>).
2216</t>
2217<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/><iref primary="true" item="Grammar" subitem="Location-v"/>
2218  <x:ref>Location</x:ref>       = "Location" ":" <x:ref>OWS</x:ref> <x:ref>Location-v</x:ref>
2219  <x:ref>Location-v</x:ref>     = <x:ref>URI-reference</x:ref>
2220</artwork></figure>
2221<figure>
2222<preamble>Examples are:</preamble><!--DO NOT DARE changing the vertical WSP below, it's necessary this way for xml2rfc-->
2223<artwork type="example">
2224  Location: http://www.example.org/pub/WWW/People.html#tim
2225</artwork></figure><figure><artwork type="example">  Location: /index.html
2226</artwork></figure>
2227<t>
2228   There are circumstances in which a fragment identifier in a Location URI
2229   would not be appropriate:
2230   <list style="symbols">
2231      <t>With a 201 Created response, because in this usage the Location header
2232      field specifies the URI for the entire created resource.</t>
2233      <t>With 305 Use Proxy.</t>
2234   </list>
2235</t>
2236<x:note>
2237  <t>
2238    <x:h>Note:</x:h> This specification does not define precedence rules
2239    for the case where the original URI, as navigated to by the user
2240    agent, and the Location header field value both contain fragment
2241    identifiers.
2242  </t>
2243</x:note>
2244<x:note>
2245  <t>
2246    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2247    from Location in that the Content-Location identifies the most specific
2248    resource corresponding to the enclosed representation.
2249    It is therefore possible for a response to contain header fields for
2250    both Location and Content-Location.
2251  </t>
2252</x:note>
2253</section>
2254
2255<section title="Max-Forwards" anchor="header.max-forwards">
2256  <iref primary="true" item="Max-Forwards header" x:for-anchor=""/>
2257  <iref primary="true" item="Headers" subitem="Max-Forwards" x:for-anchor=""/>
2258  <x:anchor-alias value="Max-Forwards"/>
2259  <x:anchor-alias value="Max-Forwards-v"/>
2260<t>
2261   The "Max-Forwards" request-header field provides a mechanism with the
2262   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>)
2263   methods to limit the number of times that the request is forwarded by
2264   proxies or gateways. This can be useful when the client is attempting to
2265   trace a request which appears to be failing or looping in mid-chain.
2266</t>
2267<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/><iref primary="true" item="Grammar" subitem="Max-Forwards-v"/>
2268  <x:ref>Max-Forwards</x:ref>   = "Max-Forwards" ":" <x:ref>OWS</x:ref> <x:ref>Max-Forwards-v</x:ref>
2269  <x:ref>Max-Forwards-v</x:ref> = 1*<x:ref>DIGIT</x:ref>
2270</artwork></figure>
2271<t>
2272   The Max-Forwards value is a decimal integer indicating the remaining
2273   number of times this request message can be forwarded.
2274</t>
2275<t>
2276   Each proxy or gateway recipient of a TRACE or OPTIONS request
2277   containing a Max-Forwards header field &MUST; check and update its
2278   value prior to forwarding the request. If the received value is zero
2279   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2280   respond as the final recipient. If the received Max-Forwards value is
2281   greater than zero, then the forwarded message &MUST; contain an updated
2282   Max-Forwards field with a value decremented by one (1).
2283</t>
2284<t>
2285   The Max-Forwards header field &MAY; be ignored for all other methods
2286   defined by this specification and for any extension methods for which
2287   it is not explicitly referred to as part of that method definition.
2288</t>
2289</section>
2290
2291<section title="Referer" anchor="header.referer">
2292  <iref primary="true" item="Referer header" x:for-anchor=""/>
2293  <iref primary="true" item="Headers" subitem="Referer" x:for-anchor=""/>
2294  <x:anchor-alias value="Referer"/>
2295  <x:anchor-alias value="Referer-v"/>
2296<t>
2297   The "Referer" [sic] request-header field allows the client to specify the
2298   URI of the resource from which the effective request URI was obtained (the
2299   "referrer", although the header field is misspelled.).
2300</t>
2301<t>
2302   The Referer header field allows servers to generate lists of back-links to
2303   resources for interest, logging, optimized caching, etc. It also allows
2304   obsolete or mistyped links to be traced for maintenance. Some servers use
2305   Referer as a means of controlling where they allow links from (so-called
2306   "deep linking"), but legitimate requests do not always
2307   contain a Referer header field.
2308</t>
2309<t>
2310   If the effective request URI was obtained from a source that does not have its own
2311   URI (e.g., input from the user keyboard), the Referer field &MUST; either be
2312   sent with the value "about:blank", or not be sent at all. Note that this
2313   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2314</t>
2315<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/><iref primary="true" item="Grammar" subitem="Referer-v"/>
2316  <x:ref>Referer</x:ref>        = "Referer" ":" <x:ref>OWS</x:ref> <x:ref>Referer-v</x:ref>
2317  <x:ref>Referer-v</x:ref>      = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2318</artwork></figure>
2319<t>
2320   Example:
2321</t>
2322<figure><artwork type="example">
2323  Referer: http://www.example.org/hypertext/Overview.html
2324</artwork></figure>
2325<t>
2326   If the field value is a relative URI, it &SHOULD; be interpreted
2327   relative to the effective request URI. The URI &MUST-NOT; include a fragment. See
2328   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2329</t>
2330</section>
2331
2332<section title="Retry-After" anchor="header.retry-after">
2333  <iref primary="true" item="Retry-After header" x:for-anchor=""/>
2334  <iref primary="true" item="Headers" subitem="Retry-After" x:for-anchor=""/>
2335  <x:anchor-alias value="Retry-After"/>
2336  <x:anchor-alias value="Retry-After-v"/>
2337<t>
2338   The response-header "Retry-After" field can be used with a 503 (Service
2339   Unavailable) response to indicate how long the service is expected to
2340   be unavailable to the requesting client. This field &MAY; also be used
2341   with any 3xx (Redirection) response to indicate the minimum time the
2342   user-agent is asked wait before issuing the redirected request.
2343</t>
2344<t>
2345   The value of this field can be either an HTTP-date or an integer number
2346   of seconds (in decimal) after the time of the response.
2347</t>
2348<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/><iref primary="true" item="Grammar" subitem="Retry-After-v"/>
2349  <x:ref>Retry-After</x:ref>   = "Retry-After" ":" <x:ref>OWS</x:ref> <x:ref>Retry-After-v</x:ref>
2350  <x:ref>Retry-After-v</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2351</artwork></figure>
2352<t anchor="rule.delta-seconds">
2353  <x:anchor-alias value="delta-seconds"/>
2354   Time spans are non-negative decimal integers, representing time in
2355   seconds.
2356</t>
2357<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2358  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2359</artwork></figure>
2360<t>
2361   Two examples of its use are
2362</t>
2363<figure><artwork type="example">
2364  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2365  Retry-After: 120
2366</artwork></figure>
2367<t>
2368   In the latter example, the delay is 2 minutes.
2369</t>
2370</section>
2371
2372<section title="Server" anchor="header.server">
2373  <iref primary="true" item="Server header" x:for-anchor=""/>
2374  <iref primary="true" item="Headers" subitem="Server" x:for-anchor=""/>
2375  <x:anchor-alias value="Server"/>
2376  <x:anchor-alias value="Server-v"/>
2377<t>
2378   The "Server" response-header field contains information about the
2379   software used by the origin server to handle the request.
2380</t>
2381<t>
2382   The field can contain multiple product tokens (&product-tokens;) and
2383   comments (&header-fields;) identifying the server and any significant
2384   subproducts. The product tokens are listed in order of their significance
2385   for identifying the application.
2386</t>
2387<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/><iref primary="true" item="Grammar" subitem="Server-v"/>
2388  <x:ref>Server</x:ref>         = "Server" ":" <x:ref>OWS</x:ref> <x:ref>Server-v</x:ref>
2389  <x:ref>Server-v</x:ref>       = <x:ref>product</x:ref>
2390                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2391</artwork></figure>
2392<t>
2393   Example:
2394</t>
2395<figure><artwork type="example">
2396  Server: CERN/3.0 libwww/2.17
2397</artwork></figure>
2398<t>
2399   If the response is being forwarded through a proxy, the proxy
2400   application &MUST-NOT; modify the Server response-header field. Instead, it
2401   &MUST; include a Via field (as described in &header-via;).
2402</t>
2403<x:note>
2404  <t>
2405    <x:h>Note:</x:h> Revealing the specific software version of the server might
2406    allow the server machine to become more vulnerable to attacks
2407    against software that is known to contain security holes. Server
2408    implementors are encouraged to make this field a configurable
2409    option.
2410  </t>
2411</x:note>
2412</section>
2413
2414<section title="User-Agent" anchor="header.user-agent">
2415  <iref primary="true" item="User-Agent header" x:for-anchor=""/>
2416  <iref primary="true" item="Headers" subitem="User-Agent" x:for-anchor=""/>
2417  <x:anchor-alias value="User-Agent"/>
2418  <x:anchor-alias value="User-Agent-v"/>
2419<t>
2420   The "User-Agent" request-header field contains information about the user
2421   agent originating the request. User agents &SHOULD; include this field with
2422   requests.
2423</t>
2424<t>
2425   Typically, it is used for statistical purposes, the tracing of protocol
2426   violations, and tailoring responses to avoid particular user agent
2427   limitations.
2428</t>
2429<t>
2430   The field can contain multiple product tokens (&product-tokens;)
2431   and comments (&header-fields;) identifying the agent and its
2432   significant subproducts. By convention, the product tokens are listed in
2433   order of their significance for identifying the application.
2434</t>
2435<t>
2436   Because this field is usually sent on every request a user agent makes,
2437   implementations are encouraged not to include needlessly fine-grained
2438   detail, and to limit (or even prohibit) the addition of subproducts by third
2439   parties. Overly long and detailed User-Agent field values make requests
2440   larger and can also be used to identify ("fingerprint") the user against
2441   their wishes.
2442</t>
2443<t>
2444   Likewise, implementations are encouraged not to use the product tokens of
2445   other implementations in order to declare compatibility with them, as this
2446   circumvents the purpose of the field. Finally, they are encouraged not to
2447   use comments to identify products; doing so makes the field value more
2448   difficult to parse.
2449</t>
2450<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/><iref primary="true" item="Grammar" subitem="User-Agent-v"/>
2451  <x:ref>User-Agent</x:ref>     = "User-Agent" ":" <x:ref>OWS</x:ref> <x:ref>User-Agent-v</x:ref>
2452  <x:ref>User-Agent-v</x:ref>   = <x:ref>product</x:ref>
2453                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2454</artwork></figure>
2455<t>
2456   Example:
2457</t>
2458<figure><artwork type="example">
2459  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2460</artwork></figure>
2461</section>
2462
2463</section>
2464
2465<section title="IANA Considerations" anchor="IANA.considerations">
2466
2467<section title="Method Registry" anchor="method.registration">
2468<t>
2469  The registration procedure for HTTP Methods is defined by
2470  <xref target="method.registry"/> of this document.
2471</t>
2472<t>
2473   The HTTP Method Registry shall be created at <eref target="http://www.iana.org/assignments/http-methods"/>
2474   and be populated with the registrations below:
2475</t>
2476<?BEGININC p2-semantics.iana-methods ?>
2477<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2478<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2479   <ttcol>Method</ttcol>
2480   <ttcol>Safe</ttcol>
2481   <ttcol>Reference</ttcol>
2482   <c>CONNECT</c>
2483   <c>no</c>
2484   <c>
2485      <xref target="CONNECT"/>
2486   </c>
2487   <c>DELETE</c>
2488   <c>no</c>
2489   <c>
2490      <xref target="DELETE"/>
2491   </c>
2492   <c>GET</c>
2493   <c>yes</c>
2494   <c>
2495      <xref target="GET"/>
2496   </c>
2497   <c>HEAD</c>
2498   <c>yes</c>
2499   <c>
2500      <xref target="HEAD"/>
2501   </c>
2502   <c>OPTIONS</c>
2503   <c>yes</c>
2504   <c>
2505      <xref target="OPTIONS"/>
2506   </c>
2507   <c>POST</c>
2508   <c>no</c>
2509   <c>
2510      <xref target="POST"/>
2511   </c>
2512   <c>PUT</c>
2513   <c>no</c>
2514   <c>
2515      <xref target="PUT"/>
2516   </c>
2517   <c>TRACE</c>
2518   <c>yes</c>
2519   <c>
2520      <xref target="TRACE"/>
2521   </c>
2522</texttable>
2523<!--(END)-->
2524<?ENDINC p2-semantics.iana-methods ?>
2525</section>
2526
2527<section title="Status Code Registry" anchor="status.code.registration">
2528<t>
2529   The registration procedure for HTTP Status Codes -- previously defined
2530   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> -- is now defined
2531   by <xref target="status.code.registry"/> of this document.
2532</t>
2533<t>
2534   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2535   shall be updated with the registrations below:
2536</t>
2537<?BEGININC p2-semantics.iana-status-codes ?>
2538<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2539<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2540   <ttcol>Value</ttcol>
2541   <ttcol>Description</ttcol>
2542   <ttcol>Reference</ttcol>
2543   <c>100</c>
2544   <c>Continue</c>
2545   <c>
2546      <xref target="status.100"/>
2547   </c>
2548   <c>101</c>
2549   <c>Switching Protocols</c>
2550   <c>
2551      <xref target="status.101"/>
2552   </c>
2553   <c>200</c>
2554   <c>OK</c>
2555   <c>
2556      <xref target="status.200"/>
2557   </c>
2558   <c>201</c>
2559   <c>Created</c>
2560   <c>
2561      <xref target="status.201"/>
2562   </c>
2563   <c>202</c>
2564   <c>Accepted</c>
2565   <c>
2566      <xref target="status.202"/>
2567   </c>
2568   <c>203</c>
2569   <c>Non-Authoritative Information</c>
2570   <c>
2571      <xref target="status.203"/>
2572   </c>
2573   <c>204</c>
2574   <c>No Content</c>
2575   <c>
2576      <xref target="status.204"/>
2577   </c>
2578   <c>205</c>
2579   <c>Reset Content</c>
2580   <c>
2581      <xref target="status.205"/>
2582   </c>
2583   <c>300</c>
2584   <c>Multiple Choices</c>
2585   <c>
2586      <xref target="status.300"/>
2587   </c>
2588   <c>301</c>
2589   <c>Moved Permanently</c>
2590   <c>
2591      <xref target="status.301"/>
2592   </c>
2593   <c>302</c>
2594   <c>Found</c>
2595   <c>
2596      <xref target="status.302"/>
2597   </c>
2598   <c>303</c>
2599   <c>See Other</c>
2600   <c>
2601      <xref target="status.303"/>
2602   </c>
2603   <c>305</c>
2604   <c>Use Proxy</c>
2605   <c>
2606      <xref target="status.305"/>
2607   </c>
2608   <c>306</c>
2609   <c>(Unused)</c>
2610   <c>
2611      <xref target="status.306"/>
2612   </c>
2613   <c>307</c>
2614   <c>Temporary Redirect</c>
2615   <c>
2616      <xref target="status.307"/>
2617   </c>
2618   <c>400</c>
2619   <c>Bad Request</c>
2620   <c>
2621      <xref target="status.400"/>
2622   </c>
2623   <c>402</c>
2624   <c>Payment Required</c>
2625   <c>
2626      <xref target="status.402"/>
2627   </c>
2628   <c>403</c>
2629   <c>Forbidden</c>
2630   <c>
2631      <xref target="status.403"/>
2632   </c>
2633   <c>404</c>
2634   <c>Not Found</c>
2635   <c>
2636      <xref target="status.404"/>
2637   </c>
2638   <c>405</c>
2639   <c>Method Not Allowed</c>
2640   <c>
2641      <xref target="status.405"/>
2642   </c>
2643   <c>406</c>
2644   <c>Not Acceptable</c>
2645   <c>
2646      <xref target="status.406"/>
2647   </c>
2648   <c>407</c>
2649   <c>Proxy Authentication Required</c>
2650   <c>
2651      <xref target="status.407"/>
2652   </c>
2653   <c>408</c>
2654   <c>Request Timeout</c>
2655   <c>
2656      <xref target="status.408"/>
2657   </c>
2658   <c>409</c>
2659   <c>Conflict</c>
2660   <c>
2661      <xref target="status.409"/>
2662   </c>
2663   <c>410</c>
2664   <c>Gone</c>
2665   <c>
2666      <xref target="status.410"/>
2667   </c>
2668   <c>411</c>
2669   <c>Length Required</c>
2670   <c>
2671      <xref target="status.411"/>
2672   </c>
2673   <c>413</c>
2674   <c>Request Entity Too Large</c>
2675   <c>
2676      <xref target="status.413"/>
2677   </c>
2678   <c>414</c>
2679   <c>URI Too Long</c>
2680   <c>
2681      <xref target="status.414"/>
2682   </c>
2683   <c>415</c>
2684   <c>Unsupported Media Type</c>
2685   <c>
2686      <xref target="status.415"/>
2687   </c>
2688   <c>417</c>
2689   <c>Expectation Failed</c>
2690   <c>
2691      <xref target="status.417"/>
2692   </c>
2693   <c>500</c>
2694   <c>Internal Server Error</c>
2695   <c>
2696      <xref target="status.500"/>
2697   </c>
2698   <c>501</c>
2699   <c>Not Implemented</c>
2700   <c>
2701      <xref target="status.501"/>
2702   </c>
2703   <c>502</c>
2704   <c>Bad Gateway</c>
2705   <c>
2706      <xref target="status.502"/>
2707   </c>
2708   <c>503</c>
2709   <c>Service Unavailable</c>
2710   <c>
2711      <xref target="status.503"/>
2712   </c>
2713   <c>504</c>
2714   <c>Gateway Timeout</c>
2715   <c>
2716      <xref target="status.504"/>
2717   </c>
2718   <c>505</c>
2719   <c>HTTP Version Not Supported</c>
2720   <c>
2721      <xref target="status.505"/>
2722   </c>
2723</texttable>
2724<!--(END)-->
2725<?ENDINC p2-semantics.iana-status-codes ?>
2726</section>
2727<section title="Header Field Registration" anchor="header.field.registration">
2728<t>
2729   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
2730   with the permanent registrations below (see <xref target="RFC3864"/>):
2731</t>
2732<?BEGININC p2-semantics.iana-headers ?>
2733<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2734<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2735   <ttcol>Header Field Name</ttcol>
2736   <ttcol>Protocol</ttcol>
2737   <ttcol>Status</ttcol>
2738   <ttcol>Reference</ttcol>
2739
2740   <c>Allow</c>
2741   <c>http</c>
2742   <c>standard</c>
2743   <c>
2744      <xref target="header.allow"/>
2745   </c>
2746   <c>Expect</c>
2747   <c>http</c>
2748   <c>standard</c>
2749   <c>
2750      <xref target="header.expect"/>
2751   </c>
2752   <c>From</c>
2753   <c>http</c>
2754   <c>standard</c>
2755   <c>
2756      <xref target="header.from"/>
2757   </c>
2758   <c>Location</c>
2759   <c>http</c>
2760   <c>standard</c>
2761   <c>
2762      <xref target="header.location"/>
2763   </c>
2764   <c>Max-Forwards</c>
2765   <c>http</c>
2766   <c>standard</c>
2767   <c>
2768      <xref target="header.max-forwards"/>
2769   </c>
2770   <c>Referer</c>
2771   <c>http</c>
2772   <c>standard</c>
2773   <c>
2774      <xref target="header.referer"/>
2775   </c>
2776   <c>Retry-After</c>
2777   <c>http</c>
2778   <c>standard</c>
2779   <c>
2780      <xref target="header.retry-after"/>
2781   </c>
2782   <c>Server</c>
2783   <c>http</c>
2784   <c>standard</c>
2785   <c>
2786      <xref target="header.server"/>
2787   </c>
2788   <c>User-Agent</c>
2789   <c>http</c>
2790   <c>standard</c>
2791   <c>
2792      <xref target="header.user-agent"/>
2793   </c>
2794</texttable>
2795<!--(END)-->
2796<?ENDINC p2-semantics.iana-headers ?>
2797<t>
2798   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2799</t>
2800</section>
2801</section>
2802
2803<section title="Security Considerations" anchor="security.considerations">
2804<t>
2805   This section is meant to inform application developers, information
2806   providers, and users of the security limitations in HTTP/1.1 as
2807   described by this document. The discussion does not include
2808   definitive solutions to the problems revealed, though it does make
2809   some suggestions for reducing security risks.
2810</t>
2811
2812<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2813<t>
2814   Like any generic data transfer protocol, HTTP cannot regulate the
2815   content of the data that is transferred, nor is there any a priori
2816   method of determining the sensitivity of any particular piece of
2817   information within the context of any given request. Therefore,
2818   applications &SHOULD; supply as much control over this information as
2819   possible to the provider of that information. Four header fields are
2820   worth special mention in this context: Server, Via, Referer and From.
2821</t>
2822<t>
2823   Revealing the specific software version of the server might allow the
2824   server machine to become more vulnerable to attacks against software
2825   that is known to contain security holes. Implementors &SHOULD; make the
2826   Server header field a configurable option.
2827</t>
2828<t>
2829   Proxies which serve as a portal through a network firewall &SHOULD;
2830   take special precautions regarding the transfer of header information
2831   that identifies the hosts behind the firewall. In particular, they
2832   &SHOULD; remove, or replace with sanitized versions, any Via fields
2833   generated behind the firewall.
2834</t>
2835<t>
2836   The Referer header field allows reading patterns to be studied and reverse
2837   links drawn. Although it can be very useful, its power can be abused
2838   if user details are not separated from the information contained in
2839   the Referer. Even when the personal information has been removed, the
2840   Referer header field might indicate a private document's URI whose
2841   publication would be inappropriate.
2842</t>
2843<t>
2844   The information sent in the From field might conflict with the user's
2845   privacy interests or their site's security policy, and hence it
2846   &SHOULD-NOT;  be transmitted without the user being able to disable,
2847   enable, and modify the contents of the field. The user &MUST; be able
2848   to set the contents of this field within a user preference or
2849   application defaults configuration.
2850</t>
2851<t>
2852   We suggest, though do not require, that a convenient toggle interface
2853   be provided for the user to enable or disable the sending of From and
2854   Referer information.
2855</t>
2856<t>
2857   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref
2858   target="header.server"/>) header fields can sometimes be used to determine
2859   that a specific client or server have a particular security hole which might
2860   be exploited. Unfortunately, this same information is often used for other
2861   valuable purposes for which HTTP currently has no better mechanism.
2862</t>
2863<t>
2864   Furthermore, the User-Agent header field may contain enough entropy to be
2865   used, possibly in conjunction with other material, to uniquely identify the
2866   user.
2867</t>
2868<t>
2869   Some methods, like TRACE (<xref target="TRACE"/>), expose information
2870   that was sent in request header fields within the body of their response.
2871   Clients &SHOULD; be careful with sensitive information, like Cookies,
2872   Authorization credentials and other header fields that might be used to
2873   collect data from the client.
2874</t> 
2875</section>
2876
2877<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2878<t>
2879   Because the source of a link might be private information or might
2880   reveal an otherwise private information source, it is strongly
2881   recommended that the user be able to select whether or not the
2882   Referer field is sent. For example, a browser client could have a
2883   toggle switch for browsing openly/anonymously, which would
2884   respectively enable/disable the sending of Referer and From
2885   information.
2886</t>
2887<t>
2888   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2889   HTTP request if the referring page was transferred with a secure
2890   protocol.
2891</t>
2892<t>
2893   Authors of services &SHOULD-NOT; use GET-based forms for the submission of
2894   sensitive data because that data will be placed in the request-target. Many
2895   existing servers, proxies, and user agents log or display the request-target
2896   in places where it might be visible to third parties. Such services can
2897   use POST-based form submission instead.
2898</t>
2899</section>
2900
2901<section title="Location Headers and Spoofing" anchor="location.spoofing">
2902<t>
2903   If a single server supports multiple organizations that do not trust
2904   one another, then it &MUST; check the values of Location and Content-Location
2905   header fields in responses that are generated under control of
2906   said organizations to make sure that they do not attempt to
2907   invalidate resources over which they have no authority.
2908</t>
2909</section>
2910
2911<section title="Security Considerations for CONNECT">
2912<t>
2913   Since tunneled data is opaque to the proxy, there are additional
2914   risks to tunneling to other well-known or reserved ports.
2915   A HTTP client CONNECTing to port 25 could relay spam
2916   via SMTP, for example. As such, proxies &SHOULD; restrict CONNECT
2917   access to a small number of known ports.
2918</t>
2919</section>
2920
2921</section>
2922
2923<section title="Acknowledgments" anchor="ack">
2924</section>
2925</middle>
2926<back>
2927
2928<references title="Normative References">
2929
2930<reference anchor="Part1">
2931  <front>
2932    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2933    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2934      <organization abbrev="Day Software">Day Software</organization>
2935      <address><email>fielding@gbiv.com</email></address>
2936    </author>
2937    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2938      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2939      <address><email>jg@freedesktop.org</email></address>
2940    </author>
2941    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2942      <organization abbrev="HP">Hewlett-Packard Company</organization>
2943      <address><email>JeffMogul@acm.org</email></address>
2944    </author>
2945    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2946      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2947      <address><email>henrikn@microsoft.com</email></address>
2948    </author>
2949    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2950      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2951      <address><email>LMM@acm.org</email></address>
2952    </author>
2953    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2954      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2955      <address><email>paulle@microsoft.com</email></address>
2956    </author>
2957    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2958      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2959      <address><email>timbl@w3.org</email></address>
2960    </author>
2961    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2962      <organization abbrev="W3C">World Wide Web Consortium</organization>
2963      <address><email>ylafon@w3.org</email></address>
2964    </author>
2965    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2966      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2967      <address><email>julian.reschke@greenbytes.de</email></address>
2968    </author>
2969    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2970  </front>
2971  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
2972  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
2973</reference>
2974
2975<reference anchor="Part3">
2976  <front>
2977    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
2978    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2979      <organization abbrev="Day Software">Day Software</organization>
2980      <address><email>fielding@gbiv.com</email></address>
2981    </author>
2982    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2983      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2984      <address><email>jg@freedesktop.org</email></address>
2985    </author>
2986    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2987      <organization abbrev="HP">Hewlett-Packard Company</organization>
2988      <address><email>JeffMogul@acm.org</email></address>
2989    </author>
2990    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2991      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2992      <address><email>henrikn@microsoft.com</email></address>
2993    </author>
2994    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2995      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2996      <address><email>LMM@acm.org</email></address>
2997    </author>
2998    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2999      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3000      <address><email>paulle@microsoft.com</email></address>
3001    </author>
3002    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3003      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3004      <address><email>timbl@w3.org</email></address>
3005    </author>
3006    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3007      <organization abbrev="W3C">World Wide Web Consortium</organization>
3008      <address><email>ylafon@w3.org</email></address>
3009    </author>
3010    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3011      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3012      <address><email>julian.reschke@greenbytes.de</email></address>
3013    </author>
3014    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3015  </front>
3016  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
3017  <x:source href="p3-payload.xml" basename="p3-payload"/>
3018</reference>
3019
3020<reference anchor="Part4">
3021  <front>
3022    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
3023    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3024      <organization abbrev="Day Software">Day Software</organization>
3025      <address><email>fielding@gbiv.com</email></address>
3026    </author>
3027    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3028      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3029      <address><email>jg@freedesktop.org</email></address>
3030    </author>
3031    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3032      <organization abbrev="HP">Hewlett-Packard Company</organization>
3033      <address><email>JeffMogul@acm.org</email></address>
3034    </author>
3035    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3036      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3037      <address><email>henrikn@microsoft.com</email></address>
3038    </author>
3039    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3040      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3041      <address><email>LMM@acm.org</email></address>
3042    </author>
3043    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3044      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3045      <address><email>paulle@microsoft.com</email></address>
3046    </author>
3047    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3048      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3049      <address><email>timbl@w3.org</email></address>
3050    </author>
3051    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3052      <organization abbrev="W3C">World Wide Web Consortium</organization>
3053      <address><email>ylafon@w3.org</email></address>
3054    </author>
3055    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3056      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3057      <address><email>julian.reschke@greenbytes.de</email></address>
3058    </author>
3059    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3060  </front>
3061  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
3062  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
3063</reference>
3064
3065<reference anchor="Part5">
3066  <front>
3067    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
3068    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3069      <organization abbrev="Day Software">Day Software</organization>
3070      <address><email>fielding@gbiv.com</email></address>
3071    </author>
3072    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3073      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3074      <address><email>jg@freedesktop.org</email></address>
3075    </author>
3076    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3077      <organization abbrev="HP">Hewlett-Packard Company</organization>
3078      <address><email>JeffMogul@acm.org</email></address>
3079    </author>
3080    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3081      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3082      <address><email>henrikn@microsoft.com</email></address>
3083    </author>
3084    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3085      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3086      <address><email>LMM@acm.org</email></address>
3087    </author>
3088    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3089      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3090      <address><email>paulle@microsoft.com</email></address>
3091    </author>
3092    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3093      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3094      <address><email>timbl@w3.org</email></address>
3095    </author>
3096    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3097      <organization abbrev="W3C">World Wide Web Consortium</organization>
3098      <address><email>ylafon@w3.org</email></address>
3099    </author>
3100    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3101      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3102      <address><email>julian.reschke@greenbytes.de</email></address>
3103    </author>
3104    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3105  </front>
3106  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
3107  <x:source href="p5-range.xml" basename="p5-range"/>
3108</reference>
3109
3110<reference anchor="Part6">
3111  <front>
3112    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
3113    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3114      <organization abbrev="Day Software">Day Software</organization>
3115      <address><email>fielding@gbiv.com</email></address>
3116    </author>
3117    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3118      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3119      <address><email>jg@freedesktop.org</email></address>
3120    </author>
3121    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3122      <organization abbrev="HP">Hewlett-Packard Company</organization>
3123      <address><email>JeffMogul@acm.org</email></address>
3124    </author>
3125    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3126      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3127      <address><email>henrikn@microsoft.com</email></address>
3128    </author>
3129    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3130      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3131      <address><email>LMM@acm.org</email></address>
3132    </author>
3133    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3134      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3135      <address><email>paulle@microsoft.com</email></address>
3136    </author>
3137    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3138      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3139      <address><email>timbl@w3.org</email></address>
3140    </author>
3141    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3142      <organization abbrev="W3C">World Wide Web Consortium</organization>
3143      <address><email>ylafon@w3.org</email></address>
3144    </author>
3145    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
3146      <address><email>mnot@mnot.net</email></address>
3147    </author>
3148    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3149      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3150      <address><email>julian.reschke@greenbytes.de</email></address>
3151    </author>
3152    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3153  </front>
3154  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
3155  <x:source href="p6-cache.xml" basename="p6-cache"/>
3156</reference>
3157
3158<reference anchor="Part7">
3159  <front>
3160    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
3161    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3162      <organization abbrev="Day Software">Day Software</organization>
3163      <address><email>fielding@gbiv.com</email></address>
3164    </author>
3165    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3166      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3167      <address><email>jg@freedesktop.org</email></address>
3168    </author>
3169    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3170      <organization abbrev="HP">Hewlett-Packard Company</organization>
3171      <address><email>JeffMogul@acm.org</email></address>
3172    </author>
3173    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3174      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3175      <address><email>henrikn@microsoft.com</email></address>
3176    </author>
3177    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3178      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3179      <address><email>LMM@acm.org</email></address>
3180    </author>
3181    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3182      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3183      <address><email>paulle@microsoft.com</email></address>
3184    </author>
3185    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3186      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3187      <address><email>timbl@w3.org</email></address>
3188    </author>
3189    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3190      <organization abbrev="W3C">World Wide Web Consortium</organization>
3191      <address><email>ylafon@w3.org</email></address>
3192    </author>
3193    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3194      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3195      <address><email>julian.reschke@greenbytes.de</email></address>
3196    </author>
3197    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3198  </front>
3199  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
3200  <x:source href="p7-auth.xml" basename="p7-auth"/>
3201</reference>
3202
3203<reference anchor="RFC2119">
3204  <front>
3205    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
3206    <author initials="S." surname="Bradner" fullname="Scott Bradner">
3207      <organization>Harvard University</organization>
3208      <address><email>sob@harvard.edu</email></address>
3209    </author>
3210    <date month="March" year="1997"/>
3211  </front>
3212  <seriesInfo name="BCP" value="14"/>
3213  <seriesInfo name="RFC" value="2119"/>
3214</reference>
3215
3216<reference anchor="RFC3986">
3217 <front>
3218  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
3219  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
3220    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3221    <address>
3222       <email>timbl@w3.org</email>
3223       <uri>http://www.w3.org/People/Berners-Lee/</uri>
3224    </address>
3225  </author>
3226  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
3227    <organization abbrev="Day Software">Day Software</organization>
3228    <address>
3229      <email>fielding@gbiv.com</email>
3230      <uri>http://roy.gbiv.com/</uri>
3231    </address>
3232  </author>
3233  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
3234    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
3235    <address>
3236      <email>LMM@acm.org</email>
3237      <uri>http://larry.masinter.net/</uri>
3238    </address>
3239  </author>
3240  <date month='January' year='2005'></date>
3241 </front>
3242 <seriesInfo name="STD" value="66"/>
3243 <seriesInfo name="RFC" value="3986"/>
3244</reference>
3245
3246<reference anchor="RFC5234">
3247  <front>
3248    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
3249    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3250      <organization>Brandenburg InternetWorking</organization>
3251      <address>
3252        <email>dcrocker@bbiw.net</email>
3253      </address> 
3254    </author>
3255    <author initials="P." surname="Overell" fullname="Paul Overell">
3256      <organization>THUS plc.</organization>
3257      <address>
3258        <email>paul.overell@thus.net</email>
3259      </address>
3260    </author>
3261    <date month="January" year="2008"/>
3262  </front>
3263  <seriesInfo name="STD" value="68"/>
3264  <seriesInfo name="RFC" value="5234"/>
3265</reference>
3266
3267</references>
3268
3269<references title="Informative References">
3270
3271<reference anchor="RFC1945">
3272  <front>
3273    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3274    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3275      <organization>MIT, Laboratory for Computer Science</organization>
3276      <address><email>timbl@w3.org</email></address>
3277    </author>
3278    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3279      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3280      <address><email>fielding@ics.uci.edu</email></address>
3281    </author>
3282    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3283      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3284      <address><email>frystyk@w3.org</email></address>
3285    </author>
3286    <date month="May" year="1996"/>
3287  </front>
3288  <seriesInfo name="RFC" value="1945"/>
3289</reference>
3290
3291<reference anchor="RFC2068">
3292  <front>
3293    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3294    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3295      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3296      <address><email>fielding@ics.uci.edu</email></address>
3297    </author>
3298    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3299      <organization>MIT Laboratory for Computer Science</organization>
3300      <address><email>jg@w3.org</email></address>
3301    </author>
3302    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3303      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3304      <address><email>mogul@wrl.dec.com</email></address>
3305    </author>
3306    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3307      <organization>MIT Laboratory for Computer Science</organization>
3308      <address><email>frystyk@w3.org</email></address>
3309    </author>
3310    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3311      <organization>MIT Laboratory for Computer Science</organization>
3312      <address><email>timbl@w3.org</email></address>
3313    </author>
3314    <date month="January" year="1997"/>
3315  </front>
3316  <seriesInfo name="RFC" value="2068"/>
3317</reference>
3318
3319<reference anchor="RFC2616">
3320  <front>
3321    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3322    <author initials="R." surname="Fielding" fullname="R. Fielding">
3323      <organization>University of California, Irvine</organization>
3324      <address><email>fielding@ics.uci.edu</email></address>
3325    </author>
3326    <author initials="J." surname="Gettys" fullname="J. Gettys">
3327      <organization>W3C</organization>
3328      <address><email>jg@w3.org</email></address>
3329    </author>
3330    <author initials="J." surname="Mogul" fullname="J. Mogul">
3331      <organization>Compaq Computer Corporation</organization>
3332      <address><email>mogul@wrl.dec.com</email></address>
3333    </author>
3334    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3335      <organization>MIT Laboratory for Computer Science</organization>
3336      <address><email>frystyk@w3.org</email></address>
3337    </author>
3338    <author initials="L." surname="Masinter" fullname="L. Masinter">
3339      <organization>Xerox Corporation</organization>
3340      <address><email>masinter@parc.xerox.com</email></address>
3341    </author>
3342    <author initials="P." surname="Leach" fullname="P. Leach">
3343      <organization>Microsoft Corporation</organization>
3344      <address><email>paulle@microsoft.com</email></address>
3345    </author>
3346    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3347      <organization>W3C</organization>
3348      <address><email>timbl@w3.org</email></address>
3349    </author>
3350    <date month="June" year="1999"/>
3351  </front>
3352  <seriesInfo name="RFC" value="2616"/>
3353</reference>
3354
3355<reference anchor='RFC2817'>
3356  <front>
3357    <title>Upgrading to TLS Within HTTP/1.1</title>
3358    <author initials='R.' surname='Khare' fullname='R. Khare'>
3359      <organization>4K Associates / UC Irvine</organization>
3360      <address><email>rohit@4K-associates.com</email></address>
3361    </author>
3362    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3363      <organization>Agranat Systems, Inc.</organization>
3364      <address><email>lawrence@agranat.com</email></address>
3365    </author>
3366    <date year='2000' month='May' />
3367  </front>
3368  <seriesInfo name='RFC' value='2817' />
3369</reference>
3370
3371<reference anchor='RFC3864'>
3372  <front>
3373    <title>Registration Procedures for Message Header Fields</title>
3374    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3375      <organization>Nine by Nine</organization>
3376      <address><email>GK-IETF@ninebynine.org</email></address>
3377    </author>
3378    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3379      <organization>BEA Systems</organization>
3380      <address><email>mnot@pobox.com</email></address>
3381    </author>
3382    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3383      <organization>HP Labs</organization>
3384      <address><email>JeffMogul@acm.org</email></address>
3385    </author>
3386    <date year='2004' month='September' />
3387  </front>
3388  <seriesInfo name='BCP' value='90' />
3389  <seriesInfo name='RFC' value='3864' />
3390</reference>
3391
3392<reference anchor='RFC5226'>
3393  <front>
3394    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3395    <author initials='T.' surname='Narten' fullname='T. Narten'>
3396      <organization>IBM</organization>
3397      <address><email>narten@us.ibm.com</email></address>
3398    </author>
3399    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3400      <organization>Google</organization>
3401      <address><email>Harald@Alvestrand.no</email></address>
3402    </author>
3403    <date year='2008' month='May' />
3404  </front>
3405  <seriesInfo name='BCP' value='26' />
3406  <seriesInfo name='RFC' value='5226' />
3407</reference>
3408
3409<reference anchor="RFC5322">
3410  <front>
3411    <title>Internet Message Format</title>
3412    <author initials="P." surname="Resnick" fullname="P. Resnick">
3413      <organization>Qualcomm Incorporated</organization>
3414    </author>
3415    <date year="2008" month="October"/>
3416  </front> 
3417  <seriesInfo name="RFC" value="5322"/>
3418</reference>
3419
3420</references>
3421
3422<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3423<t>
3424  This document takes over the Status Code Registry, previously defined
3425  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3426  (<xref target="status.code.registry"/>)
3427</t>
3428<t>
3429  Clarify definition of POST.
3430  (<xref target="POST"/>)
3431</t>
3432<t>
3433  Take over definition of CONNECT method from <xref target="RFC2817"/>.
3434  (<xref target="CONNECT"/>)
3435</t>
3436<t>
3437  Failed to consider that there are
3438  many other request methods that are safe to automatically redirect,
3439  and further that the user agent is able to make that determination
3440  based on the request method semantics.
3441  (Sections <xref format="counter" target="status.301"/>,
3442  <xref format="counter" target="status.302"/> and
3443  <xref format="counter" target="status.307"/>)
3444</t>
3445<t>
3446  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3447  It used to indicate that the target resource must be accessed through the
3448  proxy given by the Location field. The Location field gave the URI of the
3449  proxy. The recipient was expected to repeat this single request via the proxy.
3450  (<xref target="status.305"/>)
3451</t>
3452<t>
3453  Reclassify "Allow" as response header field, removing the option to
3454  specify it in a PUT request.
3455  Relax the server requirement on the contents of the Allow header field and
3456  remove requirement on clients to always trust the header field value.
3457  (<xref target="header.allow"/>)
3458</t>
3459<t>
3460  Correct syntax of Location header field to allow URI references (including
3461  relative references and fragments), as referred symbol "absoluteURI" wasn't
3462  what was expected, and add some clarifications as to when use of fragments
3463  would not be appropriate.
3464  (<xref target="header.location"/>)
3465</t>
3466<t>
3467  Allow Referer field value of "about:blank" as alternative to not specifying it.
3468  (<xref target="header.referer"/>)
3469</t>
3470<t>
3471  In the description of the Server header field, the Via field
3472  was described as a SHOULD. The requirement was and is stated
3473  correctly in the description of the Via header field in &header-via;.
3474  (<xref target="header.server"/>)
3475</t>
3476</section>
3477
3478<?BEGININC p2-semantics.abnf-appendix ?>
3479<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3480<figure>
3481<artwork type="abnf" name="p2-semantics.parsed-abnf">
3482<x:ref>Accept</x:ref> = &lt;Accept, defined in [Part3], Section 6.1&gt;
3483<x:ref>Accept-Charset</x:ref> = &lt;Accept-Charset, defined in [Part3], Section 6.2&gt;
3484<x:ref>Accept-Encoding</x:ref> = &lt;Accept-Encoding, defined in [Part3], Section 6.3&gt;
3485<x:ref>Accept-Language</x:ref> = &lt;Accept-Language, defined in [Part3], Section 6.4&gt;
3486<x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in [Part5], Section 5.1&gt;
3487<x:ref>Age</x:ref> = &lt;Age, defined in [Part6], Section 3.1&gt;
3488<x:ref>Allow</x:ref> = "Allow:" OWS Allow-v
3489<x:ref>Allow-v</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3490<x:ref>Authorization</x:ref> = &lt;Authorization, defined in [Part7], Section 4.1&gt;
3491
3492<x:ref>ETag</x:ref> = &lt;ETag, defined in [Part4], Section 6.1&gt;
3493<x:ref>Expect</x:ref> = "Expect:" OWS Expect-v
3494<x:ref>Expect-v</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3495
3496<x:ref>From</x:ref> = "From:" OWS From-v
3497<x:ref>From-v</x:ref> = mailbox
3498
3499<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3500<x:ref>Host</x:ref> = &lt;Host, defined in [Part1], Section 2.6&gt;
3501
3502<x:ref>If-Match</x:ref> = &lt;If-Match, defined in [Part4], Section 6.2&gt;
3503If-Modified-Since =
3504 &lt;If-Modified-Since, defined in [Part4], Section 6.3&gt;
3505<x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in [Part4], Section 6.4&gt;
3506<x:ref>If-Range</x:ref> = &lt;If-Range, defined in [Part5], Section 5.3&gt;
3507If-Unmodified-Since =
3508 &lt;If-Unmodified-Since, defined in [Part4], Section 6.5&gt;
3509
3510<x:ref>Location</x:ref> = "Location:" OWS Location-v
3511<x:ref>Location-v</x:ref> = URI-reference
3512
3513<x:ref>Max-Forwards</x:ref> = "Max-Forwards:" OWS Max-Forwards-v
3514<x:ref>Max-Forwards-v</x:ref> = 1*DIGIT
3515<x:ref>Method</x:ref> = %x4F.50.54.49.4F.4E.53 ; OPTIONS
3516 / %x47.45.54 ; GET
3517 / %x48.45.41.44 ; HEAD
3518 / %x50.4F.53.54 ; POST
3519 / %x50.55.54 ; PUT
3520 / %x44.45.4C.45.54.45 ; DELETE
3521 / %x54.52.41.43.45 ; TRACE
3522 / %x43.4F.4E.4E.45.43.54 ; CONNECT
3523 / extension-method
3524
3525<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3526
3527Proxy-Authenticate =
3528 &lt;Proxy-Authenticate, defined in [Part7], Section 4.2&gt;
3529Proxy-Authorization =
3530 &lt;Proxy-Authorization, defined in [Part7], Section 4.3&gt;
3531
3532<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3533<x:ref>Range</x:ref> = &lt;Range, defined in [Part5], Section 5.4&gt;
3534<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3535<x:ref>Referer</x:ref> = "Referer:" OWS Referer-v
3536<x:ref>Referer-v</x:ref> = absolute-URI / partial-URI
3537<x:ref>Retry-After</x:ref> = "Retry-After:" OWS Retry-After-v
3538<x:ref>Retry-After-v</x:ref> = HTTP-date / delta-seconds
3539
3540<x:ref>Server</x:ref> = "Server:" OWS Server-v
3541<x:ref>Server-v</x:ref> = product *( RWS ( product / comment ) )
3542<x:ref>Status-Code</x:ref> = "100" / "101" / "200" / "201" / "202" / "203" / "204" /
3543 "205" / "206" / "300" / "301" / "302" / "303" / "304" / "305" /
3544 "307" / "400" / "401" / "402" / "403" / "404" / "405" / "406" /
3545 "407" / "408" / "409" / "410" / "411" / "412" / "413" / "414" /
3546 "415" / "416" / "417" / "500" / "501" / "502" / "503" / "504" /
3547 "505" / extension-code
3548
3549<x:ref>TE</x:ref> = &lt;TE, defined in [Part1], Section 9.5&gt;
3550
3551<x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in [Part1], Section 2.6&gt;
3552<x:ref>User-Agent</x:ref> = "User-Agent:" OWS User-Agent-v
3553<x:ref>User-Agent-v</x:ref> = product *( RWS ( product / comment ) )
3554
3555<x:ref>Vary</x:ref> = &lt;Vary, defined in [Part6], Section 3.5&gt;
3556
3557WWW-Authenticate =
3558 &lt;WWW-Authenticate, defined in [Part7], Section 4.4&gt;
3559
3560<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
3561
3562<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3563
3564<x:ref>delta-seconds</x:ref> = 1*DIGIT
3565
3566<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3567<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3568<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3569 *expect-params ]
3570<x:ref>extension-code</x:ref> = 3DIGIT
3571<x:ref>extension-method</x:ref> = token
3572
3573<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3574
3575<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3576
3577<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
3578<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3579
3580<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3581
3582<x:ref>request-header</x:ref> = Accept / Accept-Charset / Accept-Encoding /
3583 Accept-Language / Authorization / Expect / From / Host / If-Match /
3584 If-Modified-Since / If-None-Match / If-Range / If-Unmodified-Since /
3585 Max-Forwards / Proxy-Authorization / Range / Referer / TE /
3586 User-Agent
3587<x:ref>response-header</x:ref> = Accept-Ranges / Age / Allow / ETag / Location /
3588 Proxy-Authenticate / Retry-After / Server / Vary / WWW-Authenticate
3589
3590<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3591</artwork>
3592</figure>
3593<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3594; Reason-Phrase defined but not used
3595; Status-Code defined but not used
3596; request-header defined but not used
3597; response-header defined but not used
3598</artwork></figure></section>
3599<?ENDINC p2-semantics.abnf-appendix ?>
3600
3601<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3602
3603<section title="Since RFC 2616">
3604<t>
3605  Extracted relevant partitions from <xref target="RFC2616"/>.
3606</t>
3607</section>
3608
3609<section title="Since draft-ietf-httpbis-p2-semantics-00">
3610<t>
3611  Closed issues:
3612  <list style="symbols"> 
3613    <t>
3614      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3615      "Via is a MUST"
3616      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3617    </t>
3618    <t>
3619      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3620      "Fragments allowed in Location"
3621      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3622    </t>
3623    <t>
3624      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3625      "Safe Methods vs Redirection"
3626      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3627    </t>
3628    <t>
3629      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3630      "Revise description of the POST method"
3631      (<eref target="http://purl.org/NET/http-errata#post"/>)
3632    </t>
3633    <t>
3634      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3635      "Normative and Informative references"
3636    </t>
3637    <t>
3638      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3639      "RFC2606 Compliance"
3640    </t>
3641    <t>
3642      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3643      "Informative references"
3644    </t>
3645    <t>
3646      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3647      "Redundant cross-references"
3648    </t>
3649  </list>
3650</t>
3651<t>
3652  Other changes:
3653  <list style="symbols"> 
3654    <t>
3655      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3656    </t>
3657  </list>
3658</t>
3659</section>
3660
3661<section title="Since draft-ietf-httpbis-p2-semantics-01">
3662<t>
3663  Closed issues:
3664  <list style="symbols"> 
3665    <t>
3666      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3667      "PUT side effects"
3668    </t>
3669    <t>
3670      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3671      "Duplicate Host header requirements"
3672    </t>
3673  </list>
3674</t>
3675<t>
3676  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3677  <list style="symbols"> 
3678    <t>
3679      Move "Product Tokens" section (back) into Part 1, as "token" is used
3680      in the definition of the Upgrade header field.
3681    </t>
3682    <t>
3683      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3684    </t>
3685    <t>
3686      Copy definition of delta-seconds from Part6 instead of referencing it.
3687    </t>
3688  </list>
3689</t>
3690</section>
3691
3692<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3693<t>
3694  Closed issues:
3695  <list style="symbols"> 
3696    <t>
3697      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3698      "Requiring Allow in 405 responses"
3699    </t>
3700    <t>
3701      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3702      "Status Code Registry"
3703    </t>
3704    <t>
3705      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3706      "Redirection vs. Location"
3707    </t>
3708    <t>
3709      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3710      "Cacheability of 303 response"
3711    </t>
3712    <t>
3713      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3714      "305 Use Proxy"
3715    </t>
3716    <t>
3717      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3718      "Classification for Allow header"
3719    </t>
3720    <t>
3721      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3722      "PUT - 'store under' vs 'store at'"
3723    </t>
3724  </list>
3725</t>
3726<t>
3727  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3728  <list style="symbols"> 
3729    <t>
3730      Reference RFC 3984, and update header field registrations for headers defined
3731      in this document.
3732    </t>
3733  </list>
3734</t>
3735<t>
3736  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3737  <list style="symbols"> 
3738    <t>
3739      Replace string literals when the string really is case-sensitive (method).
3740    </t>
3741  </list>
3742</t>
3743</section>
3744
3745<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3746<t>
3747  Closed issues:
3748  <list style="symbols"> 
3749    <t>
3750      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3751      "OPTIONS request bodies"
3752    </t>
3753    <t>
3754      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3755      "Description of CONNECT should refer to RFC2817"
3756    </t>
3757    <t>
3758      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3759      "Location Content-Location reference request/response mixup"
3760    </t>
3761  </list>
3762</t>
3763<t>
3764  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3765  <list style="symbols"> 
3766    <t>
3767      Added initial proposal for registration process, plus initial
3768      content (non-HTTP/1.1 methods to be added by a separate specification).
3769    </t>
3770  </list>
3771</t>
3772</section>
3773
3774<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3775<t>
3776  Closed issues:
3777  <list style="symbols"> 
3778    <t>
3779      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3780      "Content-*"
3781    </t>
3782    <t>
3783      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3784      "RFC 2822 is updated by RFC 5322"
3785    </t>
3786  </list>
3787</t>
3788<t>
3789  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3790  <list style="symbols"> 
3791    <t>
3792      Use "/" instead of "|" for alternatives.
3793    </t>
3794    <t>
3795      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3796      whitespace ("OWS") and required whitespace ("RWS").
3797    </t>
3798    <t>
3799      Rewrite ABNFs to spell out whitespace rules, factor out
3800      header field value format definitions.
3801    </t>
3802  </list>
3803</t>
3804</section>
3805
3806<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3807<t>
3808  Closed issues:
3809  <list style="symbols"> 
3810    <t>
3811      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3812      "Reason-Phrase BNF"
3813    </t>
3814  </list>
3815</t>
3816<t>
3817  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3818  <list style="symbols"> 
3819    <t>
3820      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3821    </t>
3822  </list>
3823</t>
3824</section>
3825
3826<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3827<t>
3828  Closed issues:
3829  <list style="symbols"> 
3830    <t>
3831      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3832      "Clarify when Referer is sent"
3833    </t>
3834    <t>
3835      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3836      "status codes vs methods"
3837    </t>
3838    <t>
3839      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3840      "Do not require "updates" relation for specs that register status codes or method names"
3841    </t>
3842  </list>
3843</t>
3844</section>
3845
3846<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3847<t>
3848  Closed issues:
3849  <list style="symbols"> 
3850    <t>
3851      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3852      "Idempotency"
3853    </t>
3854    <t>
3855      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3856      "TRACE security considerations"
3857    </t>
3858    <t>
3859      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3860      "Clarify rules for determining what entities a response carries"
3861    </t>
3862    <t>
3863      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3864      "update note citing RFC 1945 and 2068"
3865    </t>
3866    <t>
3867      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3868      "update note about redirect limit"
3869    </t>
3870    <t>
3871      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3872      "Location header ABNF should use 'URI'"
3873    </t>
3874    <t>
3875      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3876      "fragments in Location vs status 303"
3877    </t>
3878    <t>
3879      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
3880      "move IANA registrations for optional status codes"
3881    </t>
3882  </list>
3883</t>
3884<t>
3885  Partly resolved issues:
3886  <list style="symbols"> 
3887    <t>
3888      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/171"/>:
3889      "Are OPTIONS and TRACE safe?"
3890    </t>
3891  </list>
3892</t>
3893</section>
3894
3895<section title="Since draft-ietf-httpbis-p2-semantics-08" anchor="changes.since.08">
3896<t>
3897  Closed issues:
3898  <list style="symbols"> 
3899    <t>
3900      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3901      "Safe Methods vs Redirection" (we missed the introduction to the 3xx
3902      status codes when fixing this previously)
3903    </t>
3904  </list>
3905</t>
3906</section>
3907
3908<section title="Since draft-ietf-httpbis-p2-semantics-09" anchor="changes.since.09">
3909<t>
3910  Closed issues:
3911  <list style="symbols"> 
3912    <t>
3913      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
3914      "Fragment combination / precedence during redirects"
3915    </t>
3916  </list>
3917</t>
3918<t>
3919  Partly resolved issues:
3920  <list style="symbols"> 
3921    <t>
3922      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/185"/>:
3923      "Location header payload handling"
3924    </t>
3925    <t>
3926      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
3927      "Term for the requested resource's URI"
3928    </t>
3929  </list>
3930</t>
3931</section>
3932
3933<section title="Since draft-ietf-httpbis-p2-semantics-10" anchor="changes.since.10">
3934<t>
3935  Closed issues:
3936  <list style="symbols"> 
3937    <t>
3938      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
3939      "Clarify 'Requested Variant'"
3940    </t>
3941    <t>
3942      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
3943      "Clarify entity / representation / variant terminology"
3944    </t>
3945    <t>
3946      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/139"/>:
3947      "Methods and Caching"
3948    </t>
3949    <t>
3950      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/190"/>:
3951      "OPTIONS vs Max-Forwards"
3952    </t>
3953    <t>
3954      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/199"/>:
3955      "Status codes and caching"
3956    </t>
3957    <t>
3958      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
3959      "consider removing the 'changes from 2068' sections"
3960    </t>
3961  </list>
3962</t>
3963</section>
3964
3965<section title="Since draft-ietf-httpbis-p2-semantics-11" anchor="changes.since.11">
3966<t>
3967  Closed issues:
3968  <list style="symbols"> 
3969    <t>
3970      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/229"/>:
3971      "Considerations for new status codes"
3972    </t>
3973    <t>
3974      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/230"/>:
3975      "Considerations for new methods"
3976    </t>
3977    <t>
3978      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/232"/>:
3979      "User-Agent guidelines" (relating to the 'User-Agent' header field)
3980    </t>
3981  </list>
3982</t>
3983</section>
3984
3985<section title="Since draft-ietf-httpbis-p2-semantics-12" anchor="changes.since.12">
3986<t>
3987  Closed issues:
3988  <list style="symbols"> 
3989    <t>
3990      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/88"/>:
3991      "205 Bodies"
3992    </t>
3993    <t>
3994      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/239"/>:
3995      "Migrate CONNECT from RFC2817 to p2"
3996    </t>
3997  </list>
3998</t>
3999</section>
4000
4001</section>
4002
4003</back>
4004</rfc>
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