source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1042

Last change on this file since 1042 was 1042, checked in by mnot@…, 9 years ago

Remove RFC2119 language from method considerations, tweak text; for #230

  • Property svn:eol-style set to native
File size: 164.3 KB
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1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "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 header-accept              "<xref target='Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY header-accept-charset      "<xref target='Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY header-accept-encoding     "<xref target='Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY header-accept-language     "<xref target='Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY header-accept-ranges       "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY header-age                 "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41  <!ENTITY header-authorization       "<xref target='Part7' x:rel='#header.authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
42  <!ENTITY header-cache-control       "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
43  <!ENTITY header-content-location    "<xref target='Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
44  <!ENTITY header-content-range       "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
45  <!ENTITY header-etag                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
46  <!ENTITY header-expires             "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
47  <!ENTITY header-fields              "<xref target='Part1' x:rel='#header.fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
48  <!ENTITY header-host                "<xref target='Part1' x:rel='#header.host' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
49  <!ENTITY header-if-match            "<xref target='Part4' x:rel='#header.if-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
50  <!ENTITY header-if-modified-since   "<xref target='Part4' x:rel='#header.if-modified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
51  <!ENTITY header-if-none-match       "<xref target='Part4' x:rel='#header.if-none-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
52  <!ENTITY header-if-range            "<xref target='Part5' x:rel='#header.if-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
53  <!ENTITY header-if-unmodified-since "<xref target='Part4' x:rel='#header.if-unmodified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
54  <!ENTITY header-pragma              "<xref target='Part6' x:rel='#header.pragma' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
55  <!ENTITY header-proxy-authenticate  "<xref target='Part7' x:rel='#header.proxy-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
56  <!ENTITY header-proxy-authorization "<xref target='Part7' x:rel='#header.proxy-authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
57  <!ENTITY header-range               "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
58  <!ENTITY header-upgrade             "<xref target='Part1' x:rel='#header.upgrade' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
59  <!ENTITY header-te                  "<xref target='Part1' x:rel='#header.te' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
60  <!ENTITY header-vary                "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
61  <!ENTITY header-via                 "<xref target='Part1' x:rel='#header.via' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
62  <!ENTITY header-warning             "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
63  <!ENTITY header-www-authenticate    "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
64  <!ENTITY message-body               "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
65  <!ENTITY product-tokens             "<xref target='Part1' x:rel='#product.tokens' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
66  <!ENTITY media-type-message-http    "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
67  <!ENTITY status-206                 "<xref target='Part5' x:rel='#status.206' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
68  <!ENTITY status-304                 "<xref target='Part4' x:rel='#status.304' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
69  <!ENTITY status-401                 "<xref target='Part7' x:rel='#status.401' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
70  <!ENTITY status-407                 "<xref target='Part7' x:rel='#status.407' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
71  <!ENTITY status-412                 "<xref target='Part4' x:rel='#status.412' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
72  <!ENTITY status-416                 "<xref target='Part5' x:rel='#status.416' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
73  <!ENTITY p4-status-codes            "<xref target='Part4' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
74  <!ENTITY p5-status-codes            "<xref target='Part5' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
75  <!ENTITY p7-status-codes            "<xref target='Part7' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
76  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness'
77xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
78  <!ENTITY p6-explicit               "<xref target='Part6' x:rel='#calculating.freshness.lifetime'
79xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
80]>
81<?rfc toc="yes" ?>
82<?rfc symrefs="yes" ?>
83<?rfc sortrefs="yes" ?>
84<?rfc compact="yes"?>
85<?rfc subcompact="no" ?>
86<?rfc linkmailto="no" ?>
87<?rfc editing="no" ?>
88<?rfc comments="yes"?>
89<?rfc inline="yes"?>
90<?rfc rfcedstyle="yes"?>
91<?rfc-ext allow-markup-in-artwork="yes" ?>
92<?rfc-ext include-references-in-index="yes" ?>
93<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
94     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
95     xmlns:x='http://purl.org/net/xml2rfc/ext'
96     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
97<front>
98
99  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
100
101  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
102    <organization abbrev="Day Software">Day Software</organization>
103    <address>
104      <postal>
105        <street>23 Corporate Plaza DR, Suite 280</street>
106        <city>Newport Beach</city>
107        <region>CA</region>
108        <code>92660</code>
109        <country>USA</country>
110      </postal>
111      <phone>+1-949-706-5300</phone>
112      <facsimile>+1-949-706-5305</facsimile>
113      <email>fielding@gbiv.com</email>
114      <uri>http://roy.gbiv.com/</uri>
115    </address>
116  </author>
117
118  <author initials="J." surname="Gettys" fullname="Jim Gettys">
119    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
120    <address>
121      <postal>
122        <street>21 Oak Knoll Road</street>
123        <city>Carlisle</city>
124        <region>MA</region>
125        <code>01741</code>
126        <country>USA</country>
127      </postal>
128      <email>jg@freedesktop.org</email>
129      <uri>http://gettys.wordpress.com/</uri>
130    </address>
131  </author>
132 
133  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
134    <organization abbrev="HP">Hewlett-Packard Company</organization>
135    <address>
136      <postal>
137        <street>HP Labs, Large Scale Systems Group</street>
138        <street>1501 Page Mill Road, MS 1177</street>
139        <city>Palo Alto</city>
140        <region>CA</region>
141        <code>94304</code>
142        <country>USA</country>
143      </postal>
144      <email>JeffMogul@acm.org</email>
145    </address>
146  </author>
147
148  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
149    <organization abbrev="Microsoft">Microsoft Corporation</organization>
150    <address>
151      <postal>
152        <street>1 Microsoft Way</street>
153        <city>Redmond</city>
154        <region>WA</region>
155        <code>98052</code>
156        <country>USA</country>
157      </postal>
158      <email>henrikn@microsoft.com</email>
159    </address>
160  </author>
161
162  <author initials="L." surname="Masinter" fullname="Larry Masinter">
163    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
164    <address>
165      <postal>
166        <street>345 Park Ave</street>
167        <city>San Jose</city>
168        <region>CA</region>
169        <code>95110</code>
170        <country>USA</country>
171      </postal>
172      <email>LMM@acm.org</email>
173      <uri>http://larry.masinter.net/</uri>
174    </address>
175  </author>
176 
177  <author initials="P." surname="Leach" fullname="Paul J. Leach">
178    <organization abbrev="Microsoft">Microsoft Corporation</organization>
179    <address>
180      <postal>
181        <street>1 Microsoft Way</street>
182        <city>Redmond</city>
183        <region>WA</region>
184        <code>98052</code>
185      </postal>
186      <email>paulle@microsoft.com</email>
187    </address>
188  </author>
189   
190  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
191    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
192    <address>
193      <postal>
194        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
195        <street>The Stata Center, Building 32</street>
196        <street>32 Vassar Street</street>
197        <city>Cambridge</city>
198        <region>MA</region>
199        <code>02139</code>
200        <country>USA</country>
201      </postal>
202      <email>timbl@w3.org</email>
203      <uri>http://www.w3.org/People/Berners-Lee/</uri>
204    </address>
205  </author>
206
207  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
208    <organization abbrev="W3C">World Wide Web Consortium</organization>
209    <address>
210      <postal>
211        <street>W3C / ERCIM</street>
212        <street>2004, rte des Lucioles</street>
213        <city>Sophia-Antipolis</city>
214        <region>AM</region>
215        <code>06902</code>
216        <country>France</country>
217      </postal>
218      <email>ylafon@w3.org</email>
219      <uri>http://www.raubacapeu.net/people/yves/</uri>
220    </address>
221  </author>
222
223  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
224    <organization abbrev="greenbytes">greenbytes GmbH</organization>
225    <address>
226      <postal>
227        <street>Hafenweg 16</street>
228        <city>Muenster</city><region>NW</region><code>48155</code>
229        <country>Germany</country>
230      </postal>
231      <phone>+49 251 2807760</phone>
232      <facsimile>+49 251 2807761</facsimile>
233      <email>julian.reschke@greenbytes.de</email>
234      <uri>http://greenbytes.de/tech/webdav/</uri>
235    </address>
236  </author>
237
238  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
239  <workgroup>HTTPbis Working Group</workgroup>
240
241<abstract>
242<t>
243   The Hypertext Transfer Protocol (HTTP) is an application-level
244   protocol for distributed, collaborative, hypermedia information
245   systems. HTTP has been in use by the World Wide Web global information
246   initiative since 1990. This document is Part 2 of the seven-part specification
247   that defines the protocol referred to as "HTTP/1.1" and, taken together,
248   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
249   as expressed by request methods, request-header fields, response status codes,
250   and response-header fields.
251</t>
252</abstract>
253
254<note title="Editorial Note (To be removed by RFC Editor)">
255  <t>
256    Discussion of this draft should take place on the HTTPBIS working group
257    mailing list (ietf-http-wg@w3.org). The current issues list is
258    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/>
259    and related documents (including fancy diffs) can be found at
260    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
261  </t>
262  <t>
263    The changes in this draft are summarized in <xref target="changes.since.11"/>.
264  </t>
265</note>
266</front>
267<middle>
268<section title="Introduction" anchor="introduction">
269<t>
270   This document defines HTTP/1.1 request and response semantics.  Each HTTP
271   message, as defined in &messaging;, is in the form of either a request or
272   a response.  An HTTP server listens on a connection for HTTP requests and
273   responds to each request, in the order received on that connection, with
274   one or more HTTP response messages.  This document defines the commonly
275   agreed upon semantics of the HTTP uniform interface, the intentions defined
276   by each request method, and the various response messages that might be
277   expected as a result of applying that method to the target resource.
278</t>
279<t>
280   This document is currently disorganized in order to minimize the changes
281   between drafts and enable reviewers to see the smaller errata changes.
282   A future draft will reorganize the sections to better reflect the content.
283   In particular, the sections will be ordered according to the typical
284   processing of an HTTP request message (after message parsing): resource
285   mapping, general header fields, methods, request modifiers, response
286   status, and resource metadata.  The current mess reflects how widely
287   dispersed these topics and associated requirements had become in
288   <xref target="RFC2616"/>.
289</t>
290
291<section title="Requirements" anchor="intro.requirements">
292<t>
293   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
294   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
295   document are to be interpreted as described in <xref target="RFC2119"/>.
296</t>
297<t>
298   An implementation is not compliant if it fails to satisfy one or more
299   of the "MUST" or "REQUIRED" level requirements for the protocols it
300   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
301   level and all the "SHOULD" level requirements for its protocols is said
302   to be "unconditionally compliant"; one that satisfies all the "MUST"
303   level requirements but not all the "SHOULD" level requirements for its
304   protocols is said to be "conditionally compliant".
305</t>
306</section>
307
308<section title="Syntax Notation" anchor="notation">
309  <x:anchor-alias value="CR"/>
310  <x:anchor-alias value="DIGIT"/>
311  <x:anchor-alias value="LF"/>
312  <x:anchor-alias value="VCHAR"/>
313  <x:anchor-alias value="WSP"/>
314<t>
315  This specification uses the ABNF syntax defined in &notation; (which
316  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
317  <xref target="collected.abnf"/> shows the collected ABNF, with the list
318  rule expanded.
319</t>
320<t>
321  The following core rules are included by
322  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
323  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
324  DIGIT (decimal 0-9), DQUOTE (double quote),
325  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
326  OCTET (any 8-bit sequence of data), SP (space),
327  VCHAR (any visible USASCII character),
328  and WSP (whitespace).
329</t>
330
331<section title="Core Rules" anchor="core.rules">
332  <x:anchor-alias value="obs-text"/>
333  <x:anchor-alias value="quoted-string"/>
334  <x:anchor-alias value="token"/>
335  <x:anchor-alias value="OWS"/>
336  <x:anchor-alias value="RWS"/>
337<t>
338  The core rules below are defined in &basic-rules;:
339</t>
340<figure><artwork type="abnf2616">
341  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
342  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
343  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
344  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
345  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
346</artwork></figure>
347</section>
348
349<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
350  <x:anchor-alias value="absolute-URI"/>
351  <x:anchor-alias value="Accept"/>
352  <x:anchor-alias value="Accept-Charset"/>
353  <x:anchor-alias value="Accept-Encoding"/>
354  <x:anchor-alias value="Accept-Language"/>
355  <x:anchor-alias value="Accept-Ranges"/>
356  <x:anchor-alias value="Age"/>
357  <x:anchor-alias value="Authorization"/>
358  <x:anchor-alias value="comment"/>
359  <x:anchor-alias value="ETag"/>
360  <x:anchor-alias value="Host"/>
361  <x:anchor-alias value="HTTP-date"/>
362  <x:anchor-alias value="If-Match"/>
363  <x:anchor-alias value="If-Modified-Since"/>
364  <x:anchor-alias value="If-None-Match"/>
365  <x:anchor-alias value="If-Range"/>
366  <x:anchor-alias value="If-Unmodified-Since"/>
367  <x:anchor-alias value="partial-URI"/>
368  <x:anchor-alias value="product"/>
369  <x:anchor-alias value="Proxy-Authenticate"/>
370  <x:anchor-alias value="Proxy-Authorization"/>
371  <x:anchor-alias value="Range"/>
372  <x:anchor-alias value="TE"/>
373  <x:anchor-alias value="URI-reference"/>
374  <x:anchor-alias value="Vary"/>
375  <x:anchor-alias value="WWW-Authenticate"/>
376<t>
377  The ABNF rules below are defined in other parts:
378</t>
379<figure><!--Part1--><artwork type="abnf2616">
380  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
381  <x:ref>comment</x:ref>       = &lt;comment, defined in &header-fields;&gt;
382  <x:ref>Host</x:ref>          = &lt;Host, defined in &uri;&gt;
383  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
384  <x:ref>partial-URI</x:ref>   = &lt;partial-URI, defined in &uri;&gt;
385  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
386  <x:ref>TE</x:ref>            = &lt;TE, defined in &header-te;&gt;
387  <x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in &uri;&gt;
388</artwork></figure>
389<figure><!--Part3--><artwork type="abnf2616">
390  <x:ref>Accept</x:ref>        = &lt;Accept, defined in &header-accept;&gt;
391  <x:ref>Accept-Charset</x:ref> =
392             &lt;Accept-Charset, defined in &header-accept-charset;&gt;
393  <x:ref>Accept-Encoding</x:ref> =
394             &lt;Accept-Encoding, defined in &header-accept-encoding;&gt;
395  <x:ref>Accept-Language</x:ref> =
396             &lt;Accept-Language, defined in &header-accept-language;&gt;
397</artwork></figure>
398<figure><!--Part4--><artwork type="abnf2616">
399  <x:ref>ETag</x:ref>          = &lt;ETag, defined in &header-etag;&gt;
400  <x:ref>If-Match</x:ref>      = &lt;If-Match, defined in &header-if-match;&gt;
401  <x:ref>If-Modified-Since</x:ref> =
402             &lt;If-Modified-Since, defined in &header-if-modified-since;&gt;
403  <x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in &header-if-none-match;&gt;
404  <x:ref>If-Unmodified-Since</x:ref> =
405             &lt;If-Unmodified-Since, defined in &header-if-unmodified-since;&gt;
406</artwork></figure>
407<figure><!--Part5--><artwork type="abnf2616">
408  <x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in &header-accept-ranges;&gt;
409  <x:ref>If-Range</x:ref>      = &lt;If-Range, defined in &header-if-range;&gt;
410  <x:ref>Range</x:ref>         = &lt;Range, defined in &header-range;&gt;
411</artwork></figure>
412<figure><!--Part6--><artwork type="abnf2616">
413  <x:ref>Age</x:ref>           = &lt;Age, defined in &header-age;&gt;
414  <x:ref>Vary</x:ref>          = &lt;Vary, defined in &header-vary;&gt;
415</artwork><!--Part7--></figure>
416<figure><artwork type="abnf2616">
417  <x:ref>Authorization</x:ref> = &lt;Authorization, defined in &header-authorization;&gt;
418  <x:ref>Proxy-Authenticate</x:ref> =
419             &lt;Proxy-Authenticate, defined in &header-proxy-authenticate;&gt;
420  <x:ref>Proxy-Authorization</x:ref> =
421             &lt;Proxy-Authorization, defined in &header-proxy-authorization;&gt;
422  <x:ref>WWW-Authenticate</x:ref> =
423             &lt;WWW-Authenticate, defined in &header-www-authenticate;&gt;
424</artwork></figure>
425</section>
426</section>
427</section>
428
429<section title="Method" anchor="method">
430  <x:anchor-alias value="Method"/>
431  <x:anchor-alias value="extension-method"/>
432<t>
433   The Method token indicates the method to be performed on the target
434   resource (&effective-request-uri;). The method is case-sensitive.
435</t>
436<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/><iref primary="true" item="Grammar" subitem="extension-method"/>
437  <x:ref>Method</x:ref>         = <x:abnf-char-sequence>"OPTIONS"</x:abnf-char-sequence>   ; "OPTIONS", <xref target="OPTIONS"/>
438                 / <x:abnf-char-sequence>"GET"</x:abnf-char-sequence>               ; "GET", <xref target="GET"/>
439                 / <x:abnf-char-sequence>"HEAD"</x:abnf-char-sequence>            ; "HEAD", <xref target="HEAD"/>
440                 / <x:abnf-char-sequence>"POST"</x:abnf-char-sequence>            ; "POST", <xref target="POST"/>
441                 / <x:abnf-char-sequence>"PUT"</x:abnf-char-sequence>               ; "PUT", <xref target="PUT"/>
442                 / <x:abnf-char-sequence>"DELETE"</x:abnf-char-sequence>      ; "DELETE", <xref target="DELETE"/>
443                 / <x:abnf-char-sequence>"TRACE"</x:abnf-char-sequence>         ; "TRACE", <xref target="TRACE"/>
444                 / <x:abnf-char-sequence>"CONNECT"</x:abnf-char-sequence>   ; "CONNECT", <xref target="CONNECT"/>
445                 / <x:ref>extension-method</x:ref>
446  <x:ref>extension-method</x:ref> = <x:ref>token</x:ref>
447</artwork></figure>
448<t>
449   The list of methods allowed by a resource can be specified in an
450   Allow header field (<xref target="header.allow"/>). The status code of the response
451   always notifies the client whether a method is currently allowed on a
452   resource, since the set of allowed methods can change dynamically. An
453   origin server &SHOULD; respond with the status code 405 (Method Not Allowed)
454   if the method is known by the origin server but not allowed for the
455   resource, and 501 (Not Implemented) if the method is
456   unrecognized or not implemented by the origin server. The methods GET
457   and HEAD &MUST; be supported by all general-purpose servers. All other
458   methods are &OPTIONAL;; however, if the above methods are implemented,
459   they &MUST; be implemented with the same semantics as those specified
460   in <xref target="method.definitions"/>.
461</t>
462
463<section title="Method Registry" anchor="method.registry">
464<t>
465  The HTTP Method Registry defines the name space for the Method token in the
466  Request line of an HTTP request.
467</t>
468<t>
469  Registrations &MUST; include the following fields:
470  <list style="symbols">
471    <t>Method Name (see <xref target="method"/>)</t>
472    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
473    <t>Pointer to specification text</t>
474  </list>
475</t>
476<t>
477  Values to be added to this name space are subject to IETF review
478  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
479</t>
480<t>
481  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
482</t>
483
484<section title="Considerations for New Methods" anchor="considerations.for.new.methods">
485<t>
486   When it is necessary to express new semantics for a HTTP request that
487   aren't specific to a single application or media type, and currently defined
488   methods are inadequate, it may be appropriate to register a new method.
489</t>
490<t>
491   HTTP methods are generic; that is, they are potentially applicable to any
492   resource, not just one particular media type, "type" of resource, or
493   application. As such, it is preferred that new HTTP methods be registered
494   in a document that isn't specific to a single application, so that this is
495   clear.
496</t>
497<t>
498   Due to the parsing rules defined in &message-body;, definitions of HTTP
499   methods cannot prohibit the presence of a message-body on either the request
500   or the response message (with responses to HEAD requests being the single
501   exception). Definitions of new methods cannot change this rule, but they can
502   specify that only zero-length bodies (as opposed to absent bodies) are allowed.
503</t>
504<t>
505   New method definitions need to indicate whether they are safe (<xref
506   target="safe.methods"/>) and whether they are idempotent (<xref
507   target="idempotent.methods"/>). They also need to state whether they can be
508   cached (&caching;); in particular what conditions a cache may store the
509   response, and under what conditions such a stored response may be used to
510   satisfy a subsequent request.
511</t>
512</section>
513
514</section>
515</section>
516
517<section title="Request Header Fields" anchor="request.header.fields">
518  <x:anchor-alias value="request-header"/>
519<t>
520   The request-header fields allow the client to pass additional
521   information about the request, and about the client itself, to the
522   server. These fields act as request modifiers, with semantics
523   equivalent to the parameters on a programming language method
524   invocation.
525</t>
526<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="request-header"/>
527  <x:ref>request-header</x:ref> = <x:ref>Accept</x:ref>                   ; &header-accept;
528                 / <x:ref>Accept-Charset</x:ref>           ; &header-accept-charset;
529                 / <x:ref>Accept-Encoding</x:ref>          ; &header-accept-encoding;
530                 / <x:ref>Accept-Language</x:ref>          ; &header-accept-language;
531                 / <x:ref>Authorization</x:ref>            ; &header-authorization;
532                 / <x:ref>Expect</x:ref>                   ; <xref target="header.expect"/>
533                 / <x:ref>From</x:ref>                     ; <xref target="header.from"/>
534                 / <x:ref>Host</x:ref>                     ; &header-host;
535                 / <x:ref>If-Match</x:ref>                 ; &header-if-match;
536                 / <x:ref>If-Modified-Since</x:ref>        ; &header-if-modified-since;
537                 / <x:ref>If-None-Match</x:ref>            ; &header-if-none-match;
538                 / <x:ref>If-Range</x:ref>                 ; &header-if-range;
539                 / <x:ref>If-Unmodified-Since</x:ref>      ; &header-if-unmodified-since;
540                 / <x:ref>Max-Forwards</x:ref>             ; <xref target="header.max-forwards"/>
541                 / <x:ref>Proxy-Authorization</x:ref>      ; &header-proxy-authorization;
542                 / <x:ref>Range</x:ref>                    ; &header-range;
543                 / <x:ref>Referer</x:ref>                  ; <xref target="header.referer"/>
544                 / <x:ref>TE</x:ref>                       ; &header-te;
545                 / <x:ref>User-Agent</x:ref>               ; <xref target="header.user-agent"/>
546</artwork></figure>
547<t>
548   Request-header field names can be extended reliably only in
549   combination with a change in the protocol version. However, new or
550   experimental header fields &MAY; be given the semantics of request-header
551   fields if all parties in the communication recognize them to
552   be request-header fields.
553</t>
554</section>
555
556<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
557  <x:anchor-alias value="Reason-Phrase"/>
558  <x:anchor-alias value="Status-Code"/>
559  <x:anchor-alias value="extension-code"/>
560<t>
561   The Status-Code element is a 3-digit integer result code of the
562   attempt to understand and satisfy the request. The status codes listed
563   below are defined in <xref target="status.codes"/>, &p4-status-codes;,
564   &p5-status-codes;, and &p7-status-codes;.
565</t>
566<t>
567   The Reason-Phrase is intended to give a short
568   textual description of the Status-Code. The Status-Code is intended
569   for use by automata and the Reason-Phrase is intended for the human
570   user. The client is not required to examine or display the Reason-Phrase.
571</t>
572<t> 
573   The individual values of the numeric status codes defined for
574   HTTP/1.1, and an example set of corresponding Reason-Phrase values, are
575   presented below. The reason phrases listed here are only
576   recommendations -- they &MAY; be replaced by local equivalents without
577   affecting the protocol.
578</t>
579<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"/>
580  <x:ref>Status-Code</x:ref> =
581       "100"  ; <xref target="status.100"/>: Continue
582     / "101"  ; <xref target="status.101"/>: Switching Protocols
583     / "200"  ; <xref target="status.200"/>: OK
584     / "201"  ; <xref target="status.201"/>: Created
585     / "202"  ; <xref target="status.202"/>: Accepted
586     / "203"  ; <xref target="status.203"/>: Non-Authoritative Information
587     / "204"  ; <xref target="status.204"/>: No Content
588     / "205"  ; <xref target="status.205"/>: Reset Content
589     / "206"  ; &status-206;: Partial Content
590     / "300"  ; <xref target="status.300"/>: Multiple Choices
591     / "301"  ; <xref target="status.301"/>: Moved Permanently
592     / "302"  ; <xref target="status.302"/>: Found
593     / "303"  ; <xref target="status.303"/>: See Other
594     / "304"  ; &status-304;: Not Modified
595     / "305"  ; <xref target="status.305"/>: Use Proxy
596     / "307"  ; <xref target="status.307"/>: Temporary Redirect
597     / "400"  ; <xref target="status.400"/>: Bad Request
598     / "401"  ; &status-401;: Unauthorized
599     / "402"  ; <xref target="status.402"/>: Payment Required
600     / "403"  ; <xref target="status.403"/>: Forbidden
601     / "404"  ; <xref target="status.404"/>: Not Found
602     / "405"  ; <xref target="status.405"/>: Method Not Allowed
603     / "406"  ; <xref target="status.406"/>: Not Acceptable
604     / "407"  ; &status-407;: Proxy Authentication Required
605     / "408"  ; <xref target="status.408"/>: Request Time-out
606     / "409"  ; <xref target="status.409"/>: Conflict
607     / "410"  ; <xref target="status.410"/>: Gone
608     / "411"  ; <xref target="status.411"/>: Length Required
609     / "412"  ; &status-412;: Precondition Failed
610     / "413"  ; <xref target="status.413"/>: Request Entity Too Large
611     / "414"  ; <xref target="status.414"/>: URI Too Long
612     / "415"  ; <xref target="status.415"/>: Unsupported Media Type
613     / "416"  ; &status-416;: Requested range not satisfiable
614     / "417"  ; <xref target="status.417"/>: Expectation Failed
615     / "500"  ; <xref target="status.500"/>: Internal Server Error
616     / "501"  ; <xref target="status.501"/>: Not Implemented
617     / "502"  ; <xref target="status.502"/>: Bad Gateway
618     / "503"  ; <xref target="status.503"/>: Service Unavailable
619     / "504"  ; <xref target="status.504"/>: Gateway Time-out
620     / "505"  ; <xref target="status.505"/>: HTTP Version not supported
621     / <x:ref>extension-code</x:ref>
622
623  <x:ref>extension-code</x:ref> = 3<x:ref>DIGIT</x:ref>
624  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
625</artwork></figure>
626<t>
627   HTTP status codes are extensible. HTTP applications are not required
628   to understand the meaning of all registered status codes, though such
629   understanding is obviously desirable. However, applications &MUST;
630   understand the class of any status code, as indicated by the first
631   digit, and treat any unrecognized response as being equivalent to the
632   x00 status code of that class, with the exception that an
633   unrecognized response &MUST-NOT; be cached. For example, if an
634   unrecognized status code of 431 is received by the client, it can
635   safely assume that there was something wrong with its request and
636   treat the response as if it had received a 400 status code. In such
637   cases, user agents &SHOULD; present to the user the representation enclosed
638   with the response, since that representation is likely to include human-readable
639   information which will explain the unusual status.
640</t>
641
642<section title="Status Code Registry" anchor="status.code.registry">
643<t>
644  The HTTP Status Code Registry defines the name space for the Status-Code
645  token in the Status-Line of an HTTP response.
646</t>
647<t>
648  Values to be added to this name space are subject to IETF review
649  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
650</t>
651<t>
652  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
653</t>
654
655<section title="Considerations for New Status Codes" anchor="considerations.for.new.status.codes">
656<t>
657   When it is necessary to express new semantics for a HTTP response that
658   aren't specific to a single application or media type, and currently defined
659   status codes are inadequate, a new status code can be registered.
660</t>
661<t>
662   New HTTP status codes &MUST; be defined in one of the categories defined
663   in <xref target="status.codes"/>. They &MUST-NOT; disallow a response body,
664   although they &MAY; mandate a zero-length response body. They &MAY; require
665   the presence of one or more particular HTTP response header(s).
666</t>
667<t>
668   Likewise, their definitions &MAY; specify that caches are allowed to use
669   heuristics to determine their freshness (see &caching;; by default, it is
670   not allowed), and &MAY; define how to determine the resource which they
671   carry a representation for (see <xref
672   target="identifying.response.associated.with.representation"/>; by default,
673   it is anonymous).
674</t>
675<t>
676   If there are particular request conditions that produce a response
677   containing the status code (e.g., request headers and/or method(s)), they
678   &SHOULD; be described in detail.
679</t>
680<t>
681   New HTTP status codes &SHOULD; be registered in a document that isn't
682   specific to a single application or other use of HTTP, so that it's clear that
683   they are not specific to that application or extension.
684</t>
685</section>
686
687</section>
688
689</section>
690
691<section title="Response Header Fields" anchor="response.header.fields">
692  <x:anchor-alias value="response-header"/>
693<t>
694   The response-header fields allow the server to pass additional
695   information about the response which cannot be placed in the Status-Line.
696   These header fields give information about the server and about
697   further access to the target resource (&effective-request-uri;).
698</t>
699<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="response-header"/>
700  <x:ref>response-header</x:ref> = <x:ref>Accept-Ranges</x:ref>           ; &header-accept-ranges;
701                  / <x:ref>Age</x:ref>                     ; &header-age;
702                  / <x:ref>Allow</x:ref>                   ; <xref target="header.allow"/>
703                  / <x:ref>ETag</x:ref>                    ; &header-etag;
704                  / <x:ref>Location</x:ref>                ; <xref target="header.location"/>
705                  / <x:ref>Proxy-Authenticate</x:ref>      ; &header-proxy-authenticate;
706                  / <x:ref>Retry-After</x:ref>             ; <xref target="header.retry-after"/>
707                  / <x:ref>Server</x:ref>                  ; <xref target="header.server"/>
708                  / <x:ref>Vary</x:ref>                    ; &header-vary;
709                  / <x:ref>WWW-Authenticate</x:ref>        ; &header-www-authenticate;
710</artwork></figure>
711<t>
712   Response-header field names can be extended reliably only in
713   combination with a change in the protocol version. However, new or
714   experimental header fields &MAY; be given the semantics of response-header
715   fields if all parties in the communication recognize them to
716   be response-header fields.
717</t>
718</section>
719
720<section title="Representation" anchor="representation">
721<t>
722   Request and Response messages &MAY; transfer a representation if not otherwise
723   restricted by the request method or response status code. A representation
724   consists of metadata (representation header fields) and data (representation
725   body).  When a complete or partial representation is enclosed in an HTTP message,
726   it is referred to as the payload of the message. HTTP representations
727   are defined in &payload;.
728</t>
729<t>
730   A representation body is only present in a message when a message-body is
731   present, as described in &message-body;. The representation body is obtained
732   from the message-body by decoding any Transfer-Encoding that might
733   have been applied to ensure safe and proper transfer of the message.
734</t>
735
736<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
737<t>
738   It is sometimes necessary to determine an identifier for the resource
739   associated with a representation.
740</t>
741<t>
742   An HTTP request representation, when present, is always associated with an
743   anonymous (i.e., unidentified) resource.
744</t>
745<t>
746   In the common case, an HTTP response is a representation of the target
747   resource (see &effective-request-uri;). However, this is not always the
748   case. To determine the URI of the resource a response is associated with,
749   the following rules are used (with the first applicable one being selected):
750</t>
751<t><list style="numbers">
752   <t>If the response status code is 200 or 203 and the request method was GET,
753   the response payload is a representation of the target resource.</t>
754   <t>If the response status code is 204, 206, or 304 and the request method was GET
755   or HEAD, the response payload is a partial representation of the target
756   (see &combining-responses;).</t>
757   <t>If the response has a Content-Location header field, and that URI is the same
758   as the effective request URI, the response payload is a representation of the
759   target resource.</t>
760   <t>If the response has a Content-Location header field, and that URI is not the
761   same as the effective request URI, then the response asserts that its
762   payload is a representation of the resource identified by the
763   Content-Location URI. However, such an assertion cannot be trusted unless
764   it can be verified by other means (not defined by HTTP).</t>
765   <t>Otherwise, the response is a representation of an anonymous (i.e.,
766   unidentified) resource.</t>
767</list></t>
768<t>
769  <cref anchor="TODO-req-uri">
770   The comparison function is going to have to be defined somewhere,
771   because we already need to compare URIs for things like cache invalidation.</cref>
772</t>
773</section>
774
775</section>
776
777
778<section title="Method Definitions" anchor="method.definitions">
779<t>
780   The set of common methods for HTTP/1.1 is defined below. Although
781   this set can be expanded, additional methods cannot be assumed to
782   share the same semantics for separately extended clients and servers.
783</t>
784
785<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
786
787<section title="Safe Methods" anchor="safe.methods">
788<iref item="Safe Methods" primary="true"/>
789<t>
790   Implementors need to be aware that the software represents the user in
791   their interactions over the Internet, and need to allow
792   the user to be aware of any actions they take which might have an
793   unexpected significance to themselves or others.
794</t>
795<t>
796   In particular, the convention has been established that the GET, HEAD,
797   OPTIONS, and TRACE methods &SHOULD-NOT; have the significance of taking an action
798   other than retrieval. These methods ought to be considered "<x:dfn anchor="safe">safe</x:dfn>".
799   This allows user agents to represent other methods, such as POST, PUT
800   and DELETE, in a special way, so that the user is made aware of the
801   fact that a possibly unsafe action is being requested.
802</t>
803<t>
804   Naturally, it is not possible to ensure that the server does not
805   generate side-effects as a result of performing a GET request; in
806   fact, some dynamic resources consider that a feature. The important
807   distinction here is that the user did not request the side-effects,
808   so therefore cannot be held accountable for them.
809</t>
810</section>
811
812<section title="Idempotent Methods" anchor="idempotent.methods">
813<iref item="Idempotent Methods" primary="true"/>
814<t>
815   Methods can also have the property of "idempotence" in that, aside
816   from error or expiration issues, the intended effect of multiple
817   identical requests is the same as for a single request.
818   The methods PUT, DELETE, and all safe methods are idempotent.
819   It is important to note that idempotence refers only to changes
820   requested by the client: a server is free to change its state due
821   to multiple requests for the purpose of tracking those requests,
822   versioning of results, etc.
823</t>
824</section>
825</section>
826
827<section title="OPTIONS" anchor="OPTIONS">
828  <rdf:Description>
829    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
830  </rdf:Description>
831  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
832  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
833<t>
834   The OPTIONS method represents a request for information about the
835   communication options available on the request/response chain
836   identified by the effective request URI. This method allows the client to
837   determine the options and/or requirements associated with a resource,
838   or the capabilities of a server, without implying a resource action
839   or initiating a resource retrieval.
840</t>
841<t>
842   Responses to this method are not cacheable.
843</t>
844<t>
845   If the OPTIONS request includes a message-body (as indicated by the
846   presence of Content-Length or Transfer-Encoding), then the media type
847   &MUST; be indicated by a Content-Type field. Although this
848   specification does not define any use for such a body, future
849   extensions to HTTP might use the OPTIONS body to make more detailed
850   queries on the server.
851</t>
852<t>
853   If the request-target is an asterisk ("*"), the OPTIONS request is
854   intended to apply to the server in general rather than to a specific
855   resource. Since a server's communication options typically depend on
856   the resource, the "*" request is only useful as a "ping" or "no-op"
857   type of method; it does nothing beyond allowing the client to test
858   the capabilities of the server. For example, this can be used to test
859   a proxy for HTTP/1.1 compliance (or lack thereof).
860</t>
861<t>
862   If the request-target is not an asterisk, the OPTIONS request applies
863   only to the options that are available when communicating with that
864   resource.
865</t>
866<t>
867   A 200 response &SHOULD; include any header fields that indicate
868   optional features implemented by the server and applicable to that
869   resource (e.g., Allow), possibly including extensions not defined by
870   this specification. The response body, if any, &SHOULD; also include
871   information about the communication options. The format for such a
872   body is not defined by this specification, but might be defined by
873   future extensions to HTTP. Content negotiation &MAY; be used to select
874   the appropriate response format. If no response body is included, the
875   response &MUST; include a Content-Length field with a field-value of
876   "0".
877</t>
878<t>
879   The Max-Forwards request-header field &MAY; be used to target a
880   specific proxy in the request chain (see <xref target="header.max-forwards"/>).
881   If no Max-Forwards field is present in the request, then the forwarded
882   request &MUST-NOT; include a Max-Forwards field.
883</t>
884</section>
885
886<section title="GET" anchor="GET">
887  <rdf:Description>
888    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
889  </rdf:Description>
890  <iref primary="true" item="GET method" x:for-anchor=""/>
891  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
892<t>
893   The GET method means retrieve whatever information (in the form of a
894   representation) currently corresponds to the target resource.
895</t>
896<t>   
897   If the target resource is a data-producing process, it is the
898   produced data which shall be returned as the representation in the response and not
899   the source text of the process, unless that text happens to be the output of
900   the process.
901</t>
902<t>
903   The semantics of the GET method change to a "conditional GET" if the
904   request message includes an If-Modified-Since, If-Unmodified-Since,
905   If-Match, If-None-Match, or If-Range header field. A conditional GET
906   method requests that the representation be transferred only under the
907   circumstances described by the conditional header field(s). The
908   conditional GET method is intended to reduce unnecessary network
909   usage by allowing cached representations to be refreshed without requiring
910   multiple requests or transferring data already held by the client.
911</t>
912<t>
913   The semantics of the GET method change to a "partial GET" if the
914   request message includes a Range header field. A partial GET requests
915   that only part of the representation be transferred, as described in &header-range;.
916   The partial GET method is intended to reduce unnecessary
917   network usage by allowing partially-retrieved representations to be
918   completed without transferring data already held by the client.
919</t>
920<t>
921   The response to a GET request is cacheable and &MAY; be used to satisfy
922   subsequent GET and HEAD requests (see &caching;).
923</t>
924<t>
925   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
926</t>
927</section>
928
929<section title="HEAD" anchor="HEAD">
930  <rdf:Description>
931    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
932  </rdf:Description>
933  <iref primary="true" item="HEAD method" x:for-anchor=""/>
934  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
935<t>
936   The HEAD method is identical to GET except that the server &MUST-NOT;
937   return a message-body in the response. The metadata contained
938   in the HTTP header fields in response to a HEAD request &SHOULD; be identical
939   to the information sent in response to a GET request. This method can
940   be used for obtaining metadata about the representation implied by the
941   request without transferring the representation body. This method is
942   often used for testing hypertext links for validity, accessibility,
943   and recent modification.
944</t>
945<t>
946   The response to a HEAD request is cacheable and &MAY; be used to satisfy
947   a subsequent HEAD request; see &caching;. It also &MAY; be used to update a previously cached
948   representation from that resource; if the new field values
949   indicate that the cached representation differs from the current representation (as
950   would be indicated by a change in Content-Length, Content-MD5, ETag
951   or Last-Modified), then the cache &MUST; treat the cache entry as
952   stale.
953</t>
954</section>
955
956<section title="POST" anchor="POST">
957  <iref primary="true" item="POST method" x:for-anchor=""/>
958  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
959<t>
960   The POST method is used to request that the origin server accept the
961   representation enclosed in the request as data to be processed by the
962   target resource. POST is designed to allow a uniform method to cover the
963   following functions:
964  <list style="symbols">
965    <t>
966      Annotation of existing resources;
967    </t>
968    <t>
969        Posting a message to a bulletin board, newsgroup, mailing list,
970        or similar group of articles;
971    </t>
972    <t>
973        Providing a block of data, such as the result of submitting a
974        form, to a data-handling process;
975    </t>
976    <t>
977        Extending a database through an append operation.
978    </t>
979  </list>
980</t>
981<t>
982   The actual function performed by the POST method is determined by the
983   server and is usually dependent on the effective request URI.
984</t>
985<t>
986   The action performed by the POST method might not result in a
987   resource that can be identified by a URI. In this case, either 200
988   (OK) or 204 (No Content) is the appropriate response status code,
989   depending on whether or not the response includes a representation that
990   describes the result.
991</t>
992<t>
993   If a resource has been created on the origin server, the response
994   &SHOULD; be 201 (Created) and contain a representation which describes the
995   status of the request and refers to the new resource, and a Location
996   header field (see <xref target="header.location"/>).
997</t>
998<t>
999   Responses to POST requests are only cacheable when they
1000   include explicit freshness information (see &p6-explicit;). A
1001   cached POST response with a Content-Location header field
1002   (see &header-content-location;) whose value is the effective
1003   Request URI &MAY; be used to satisfy subsequent GET and HEAD requests.
1004</t>
1005<t>
1006   Note that POST caching is not widely implemented.
1007   However, the 303 (See Other) response can be used to direct the
1008   user agent to retrieve a cacheable resource.
1009</t>
1010</section>
1011
1012<section title="PUT" anchor="PUT">
1013  <iref primary="true" item="PUT method" x:for-anchor=""/>
1014  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
1015<t>
1016   The PUT method requests that the enclosed representation be stored at the
1017   effective request URI. If the effective request URI refers to an already
1018   existing resource, the enclosed representation &SHOULD; be considered a
1019   modified version of the one residing on the origin server. Otherwise, if the
1020   effective request URI does not point to an existing resource, and that URI is
1021   capable of being defined as a new resource by the requesting user
1022   agent, the origin server can create the resource with that URI.
1023</t>
1024<t>   
1025   If a new resource is created at the effective request URI, the origin
1026   server &MUST; inform the user agent
1027   via the 201 (Created) response. If an existing resource is modified,
1028   either the 200 (OK) or 204 (No Content) response codes &SHOULD; be sent
1029   to indicate successful completion of the request.
1030</t>
1031<t>   
1032   If the target resource could not be created or modified, an appropriate
1033   error response &SHOULD; be given that reflects the nature of the problem.
1034   The recipient of the representation &MUST-NOT; ignore any Content-*
1035   header fields (headers starting with the prefix "Content-") that it does
1036   not understand or implement
1037   and &MUST; return a 501 (Not Implemented) response in such cases.
1038</t>
1039<t>
1040   If the request passes through a cache that has one or more stored
1041   responses for the effective request URI, those stored responses
1042   &SHOULD; be marked as stale if the response to the PUT request
1043   has a success status code. Responses to the PUT method are
1044   not cacheable.
1045</t>
1046<t>
1047   The fundamental difference between the POST and PUT requests is
1048   reflected in the different meaning of the effective request URI. The URI in a
1049   POST request identifies the resource that will handle the enclosed
1050   representation. That resource might be a data-accepting process, a gateway to
1051   some other protocol, or a document that accepts annotations.
1052   In contrast, the URI in a PUT request identifies the resource for
1053   which enclosed representation is a new or replacement value; the
1054   user agent knows what URI is intended and the server &MUST-NOT; attempt
1055   to apply the request to some other resource.
1056   If the server desires that the request be applied to a different URI,
1057   it &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
1058   then make its own decision regarding whether or not to redirect the
1059   request.
1060</t>
1061<t>
1062   A single resource &MAY; be identified by many different URIs. For
1063   example, an article might have a URI for identifying "the current
1064   version" which is separate from the URI identifying each particular
1065   version. In this case, a PUT request on a general URI might result in
1066   several other URIs being defined by the origin server.
1067</t>
1068<t>
1069   HTTP/1.1 does not define how a PUT method affects the state of an
1070   origin server.
1071</t>
1072<t>
1073   Header fields in a PUT request that are recognized as representation
1074   metadata &SHOULD; be applied to the resource created or modified by
1075   the PUT.  Unrecognized header fields &SHOULD; be ignored.
1076</t>
1077</section>
1078
1079<section title="DELETE" anchor="DELETE">
1080  <iref primary="true" item="DELETE method" x:for-anchor=""/>
1081  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
1082<t>
1083   The DELETE method requests that the origin server delete the target
1084   resource. This method &MAY; be overridden by
1085   human intervention (or other means) on the origin server. The client cannot
1086   be guaranteed that the operation has been carried out, even if the
1087   status code returned from the origin server indicates that the action
1088   has been completed successfully. However, the server &SHOULD-NOT; 
1089   indicate success unless, at the time the response is given, it
1090   intends to delete the resource or move it to an inaccessible
1091   location.
1092</t>
1093<t>
1094   A successful response &SHOULD; be 200 (OK) if the response includes an
1095   representation describing the status, 202 (Accepted) if the action has not
1096   yet been enacted, or 204 (No Content) if the action has been enacted
1097   but the response does not include a representation.
1098</t>
1099<t>
1100   If the request passes through a cache and the effective request URI
1101   identifies one or more currently cached representations, those entries &SHOULD; be
1102   treated as stale. Responses to the DELETE method are not cacheable.
1103</t>
1104</section>
1105
1106<section title="TRACE" anchor="TRACE">
1107  <rdf:Description>
1108    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1109  </rdf:Description>
1110  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1111  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1112<t>
1113   The TRACE method is used to invoke a remote, application-layer loop-back
1114   of the request message. The final recipient of the request
1115   &SHOULD; reflect the message received back to the client as the
1116   message-body of a 200 (OK) response. The final recipient is either the
1117   origin server or the first proxy or gateway to receive a Max-Forwards
1118   value of zero (0) in the request (see <xref target="header.max-forwards"/>).
1119   A TRACE request &MUST-NOT; include a message-body.
1120</t>
1121<t>
1122   TRACE allows the client to see what is being received at the other
1123   end of the request chain and use that data for testing or diagnostic
1124   information. The value of the Via header field (&header-via;) is of
1125   particular interest, since it acts as a trace of the request chain.
1126   Use of the Max-Forwards header field allows the client to limit the
1127   length of the request chain, which is useful for testing a chain of
1128   proxies forwarding messages in an infinite loop.
1129</t>
1130<t>
1131   If the request is valid, the response &SHOULD; have a Content-Type of
1132   "message/http" (see &media-type-message-http;) and contain a message-body
1133   that encloses a copy of the entire request message.
1134   Responses to the TRACE method are not cacheable.
1135</t>
1136</section>
1137
1138<section title="CONNECT" anchor="CONNECT">
1139  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1140  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1141<t>
1142   This specification reserves the method name CONNECT for use with a
1143   proxy that can dynamically switch to being a tunnel (e.g., SSL
1144   tunneling <xref target="RFC2817"/>).
1145</t>
1146</section>
1147</section>
1148
1149
1150<section title="Status Code Definitions" anchor="status.codes">
1151<t>
1152   Each Status-Code is described below, including any metadata required
1153   in the response.
1154</t>
1155
1156<section title="Informational 1xx" anchor="status.1xx">
1157<t>
1158   This class of status code indicates a provisional response,
1159   consisting only of the Status-Line and optional header fields, and is
1160   terminated by an empty line. There are no required header fields for this
1161   class of status code. Since HTTP/1.0 did not define any 1xx status
1162   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1163   except under experimental conditions.
1164</t>
1165<t>
1166   A client &MUST; be prepared to accept one or more 1xx status responses
1167   prior to a regular response, even if the client does not expect a 100
1168   (Continue) status message. Unexpected 1xx status responses &MAY; be
1169   ignored by a user agent.
1170</t>
1171<t>
1172   Proxies &MUST; forward 1xx responses, unless the connection between the
1173   proxy and its client has been closed, or unless the proxy itself
1174   requested the generation of the 1xx response. (For example, if a
1175   proxy adds a "Expect: 100-continue" field when it forwards a request,
1176   then it need not forward the corresponding 100 (Continue)
1177   response(s).)
1178</t>
1179
1180<section title="100 Continue" anchor="status.100">
1181  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1182  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1183<t>
1184   The client &SHOULD; continue with its request. This interim response is
1185   used to inform the client that the initial part of the request has
1186   been received and has not yet been rejected by the server. The client
1187   &SHOULD; continue by sending the remainder of the request or, if the
1188   request has already been completed, ignore this response. The server
1189   &MUST; send a final response after the request has been completed. See
1190   &use100; for detailed discussion of the use and handling of this
1191   status code.
1192</t>
1193</section>
1194
1195<section title="101 Switching Protocols" anchor="status.101">
1196  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1197  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1198<t>
1199   The server understands and is willing to comply with the client's
1200   request, via the Upgrade message header field (&header-upgrade;), for a
1201   change in the application protocol being used on this connection. The
1202   server will switch protocols to those defined by the response's
1203   Upgrade header field immediately after the empty line which
1204   terminates the 101 response.
1205</t>
1206<t>
1207   The protocol &SHOULD; be switched only when it is advantageous to do
1208   so. For example, switching to a newer version of HTTP is advantageous
1209   over older versions, and switching to a real-time, synchronous
1210   protocol might be advantageous when delivering resources that use
1211   such features.
1212</t>
1213</section>
1214</section>
1215
1216<section title="Successful 2xx" anchor="status.2xx">
1217<t>
1218   This class of status code indicates that the client's request was
1219   successfully received, understood, and accepted.
1220</t>
1221
1222<section title="200 OK" anchor="status.200">
1223  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1224  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1225<t>
1226   The request has succeeded. The payload returned with the response
1227   is dependent on the method used in the request, for example:
1228  <list style="hanging">
1229    <t hangText="GET">
1230          a representation of the target resource is sent in the response;
1231    </t>
1232    <t hangText="HEAD">
1233          the same representation as GET, except without the message-body;
1234    </t>
1235    <t hangText="POST">
1236      a representation describing or containing the result of the action;
1237    </t>
1238    <t hangText="TRACE">
1239      a representation containing the request message as received by the
1240      end server.
1241    </t>
1242  </list>
1243</t>
1244<t>
1245   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1246   freshness for 200 responses.
1247</t>
1248</section>
1249
1250<section title="201 Created" anchor="status.201">
1251  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1252  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1253<t>
1254   The request has been fulfilled and has resulted in a new resource being
1255   created. The newly created resource can be referenced by the URI(s)
1256   returned in the payload of the response, with the most specific URI
1257   for the resource given by a Location header field. The response
1258   &SHOULD; include a payload containing a list of resource
1259   characteristics and location(s) from which the user or user agent can
1260   choose the one most appropriate. The payload format is specified by
1261   the media type given in the Content-Type header field. The origin
1262   server &MUST; create the resource before returning the 201 status code.
1263   If the action cannot be carried out immediately, the server &SHOULD;
1264   respond with 202 (Accepted) response instead.
1265</t>
1266<t>
1267   A 201 response &MAY; contain an ETag response header field indicating
1268   the current value of the entity-tag for the representation of the resource
1269   just created (see &header-etag;).
1270</t>
1271</section>
1272
1273<section title="202 Accepted" anchor="status.202">
1274  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1275  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1276<t>
1277   The request has been accepted for processing, but the processing has
1278   not been completed.  The request might or might not eventually be
1279   acted upon, as it might be disallowed when processing actually takes
1280   place. There is no facility for re-sending a status code from an
1281   asynchronous operation such as this.
1282</t>
1283<t>
1284   The 202 response is intentionally non-committal. Its purpose is to
1285   allow a server to accept a request for some other process (perhaps a
1286   batch-oriented process that is only run once per day) without
1287   requiring that the user agent's connection to the server persist
1288   until the process is completed. The representation returned with this
1289   response &SHOULD; include an indication of the request's current status
1290   and either a pointer to a status monitor or some estimate of when the
1291   user can expect the request to be fulfilled.
1292</t>
1293</section>
1294
1295<section title="203 Non-Authoritative Information" anchor="status.203">
1296  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1297  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1298<t>
1299   The returned metadata in the header fields is not the
1300   definitive set as available from the origin server, but is gathered
1301   from a local or a third-party copy. The set presented &MAY; be a subset
1302   or superset of the original version. For example, including local
1303   annotation information about the resource might result in a superset
1304   of the metadata known by the origin server. Use of this
1305   response code is not required and is only appropriate when the
1306   response would otherwise be 200 (OK).
1307</t>
1308<t>
1309   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1310   freshness for 203 responses.
1311</t>
1312
1313</section>
1314
1315<section title="204 No Content" anchor="status.204">
1316  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1317  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1318<t>
1319   The server has successfully fulfilled the request, but there is no
1320   additional content to return in the response payload body.  The
1321   resource metadata and representation metadata in the response message's
1322   header fields refer to the target resource
1323   and its current representation, respectively, after the requested action.
1324   For example, if a 204 status code is received in response to a PUT
1325   and the response contains an ETag header field, then the value of
1326   that field is the current entity-tag for the representation that
1327   was successfully PUT.
1328</t>
1329<t>
1330   If the client is a user agent, it &SHOULD-NOT; change its document view
1331   from that which caused the request to be sent. This response is
1332   primarily intended to allow input for actions to take place without
1333   causing a change to the user agent's active document view, although
1334   any new or updated metadata &SHOULD; be applied to the document
1335   currently in the user agent's active view.
1336</t>
1337<t>
1338   The 204 response &MUST-NOT; include a message-body, and thus is always
1339   terminated by the first empty line after the header fields.
1340</t>
1341</section>
1342
1343<section title="205 Reset Content" anchor="status.205">
1344  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1345  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1346<t>
1347   The server has fulfilled the request and the user agent &SHOULD; reset
1348   the document view which caused the request to be sent. This response
1349   is primarily intended to allow input for actions to take place via
1350   user input, followed by a clearing of the form in which the input is
1351   given so that the user can easily initiate another input action. The
1352   response &MUST-NOT; include a message-body.
1353</t>
1354</section>
1355
1356<section title="206 Partial Content" anchor="status.206">
1357  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1358  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1359  <rdf:Description>
1360    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1361  </rdf:Description>
1362<t>
1363   The server has fulfilled the partial GET request for the resource
1364   and the enclosed payload is a partial representation as defined in &status-206;.
1365</t>
1366<t>
1367   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1368   freshness for 206 responses.
1369</t>
1370</section>
1371</section>
1372
1373<section title="Redirection 3xx" anchor="status.3xx">
1374<t>
1375   This class of status code indicates that further action needs to be
1376   taken by the user agent in order to fulfill the request.  The action
1377   required &MAY; be carried out by the user agent without interaction
1378   with the user if and only if the method used in the second request is
1379   known to be "safe", as defined in <xref target="safe.methods"/>.
1380   A client &SHOULD; detect infinite redirection loops, since such loops
1381   generate network traffic for each redirection.
1382</t>
1383<x:note>
1384  <t>
1385    <x:h>Note:</x:h> An earlier version of this specification recommended a
1386    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1387    Content developers need to be aware that some clients might
1388    implement such a fixed limitation.
1389  </t>
1390</x:note>
1391
1392<section title="300 Multiple Choices" anchor="status.300">
1393  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1394  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1395<t>
1396   The target resource has more than one
1397   representation, each with its own specific location, and agent-driven
1398   negotiation information (&content-negotiation;) is being provided so that
1399   the user (or user agent) can select a preferred representation by
1400   redirecting its request to that location.
1401</t>
1402<t>
1403   Unless it was a HEAD request, the response &SHOULD; include a representation
1404   containing a list of representation metadata and location(s) from
1405   which the user or user agent can choose the one most appropriate. The
1406   data format is specified by the media type given in the Content-Type
1407   header field. Depending upon the format and the capabilities of
1408   the user agent, selection of the most appropriate choice &MAY; be
1409   performed automatically. However, this specification does not define
1410   any standard for such automatic selection.
1411</t>
1412<t>
1413   If the server has a preferred choice of representation, it &SHOULD;
1414   include the specific URI for that representation in the Location
1415   field; user agents &MAY; use the Location field value for automatic
1416   redirection.
1417</t>
1418<t>
1419   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1420   freshness for 300 responses.
1421</t>
1422
1423</section>
1424
1425<section title="301 Moved Permanently" anchor="status.301">
1426  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1427  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1428<t>
1429   The target resource has been assigned a new permanent URI and any
1430   future references to this resource &SHOULD; use one of the returned
1431   URIs.  Clients with link editing capabilities ought to automatically
1432   re-link references to the effective request URI to one or more of the new
1433   references returned by the server, where possible.
1434</t>
1435<t>
1436   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1437   freshness for 301 responses.
1438</t>
1439<t>
1440   The new permanent URI &SHOULD; be given by the Location field in the
1441   response. Unless the request method was HEAD, the representation of the
1442   response &SHOULD; contain a short hypertext note with a hyperlink to
1443   the new URI(s).
1444</t>
1445<t>
1446   If the 301 status code is received in response to a request method
1447   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1448   then the request &MAY; be automatically redirected by the user agent without
1449   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1450   request unless it can be confirmed by the user, since this might
1451   change the conditions under which the request was issued.
1452</t>
1453<x:note>
1454  <t>
1455    <x:h>Note:</x:h> When automatically redirecting a POST request after
1456    receiving a 301 status code, some existing HTTP/1.0 user agents
1457    will erroneously change it into a GET request.
1458  </t>
1459</x:note>
1460</section>
1461
1462<section title="302 Found" anchor="status.302">
1463  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1464  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1465<t>
1466   The target resource resides temporarily under a different URI.
1467   Since the redirection might be altered on occasion, the client &SHOULD;
1468   continue to use the effective request URI for future requests.
1469</t>
1470<t>
1471   The temporary URI &SHOULD; be given by the Location field in the
1472   response. Unless the request method was HEAD, the representation of the
1473   response &SHOULD; contain a short hypertext note with a hyperlink to
1474   the new URI(s).
1475</t>
1476<t>
1477   If the 302 status code is received in response to a request method
1478   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1479   then the request &MAY; be automatically redirected by the user agent without
1480   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1481   request unless it can be confirmed by the user, since this might
1482   change the conditions under which the request was issued.
1483</t>
1484<x:note>
1485  <t>
1486    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1487    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1488    specify that the client is not allowed to change the method on the
1489    redirected request.  However, most existing user agent implementations
1490    treat 302 as if it were a 303 response, performing a GET on the Location
1491    field-value regardless of the original request method. Therefore, a
1492    previous version of this specification
1493    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1494    status codes
1495    <xref target="status.303" format="none">303</xref> and
1496    <xref target="status.307" format="none">307</xref> for servers that wish
1497    to make unambiguously clear which kind of reaction is expected of the
1498    client.
1499  </t>
1500</x:note>
1501</section>
1502
1503<section title="303 See Other" anchor="status.303">
1504  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1505  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1506<t>
1507   The server directs the user agent to a different resource, indicated
1508   by a URI in the Location header field, that provides an indirect
1509   response to the original request.  The user agent &MAY; perform a GET
1510   request on the URI in the Location field in order to obtain a
1511   representation corresponding to the response, be redirected again,
1512   or end with an error status.  The Location URI is not a substitute
1513   reference for the effective request URI.
1514</t>
1515<t>
1516   The 303 status code is generally applicable to any HTTP method.  It is
1517   primarily used to allow the output of a POST action to redirect
1518   the user agent to a selected resource, since doing so provides the
1519   information corresponding to the POST response in a form that
1520   can be separately identified, bookmarked, and cached independent
1521   of the original request.
1522</t>
1523<t>
1524   A 303 response to a GET request indicates that the requested
1525   resource does not have a representation of its own that can be
1526   transferred by the server over HTTP.  The Location URI indicates a
1527   resource that is descriptive of the target resource, such that the
1528   follow-on representation might be useful to recipients without
1529   implying that it adequately represents the target resource.
1530   Note that answers to the questions of what can be represented, what
1531   representations are adequate, and what might be a useful description
1532   are outside the scope of HTTP and thus entirely determined by the
1533   URI owner(s).
1534</t>
1535<t>
1536   Except for responses to a HEAD request, the representation of a 303
1537   response &SHOULD; contain a short hypertext note with a hyperlink
1538   to the Location URI.
1539</t>
1540</section>
1541
1542<section title="304 Not Modified" anchor="status.304">
1543  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1544  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1545  <rdf:Description>
1546    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1547  </rdf:Description>
1548<t>
1549   The response to the request has not been modified since the conditions
1550   indicated by the client's conditional GET request, as defined in &status-304;.
1551</t>
1552</section>
1553
1554<section title="305 Use Proxy" anchor="status.305">
1555  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1556  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1557<t>
1558   The 305 status code was defined in a previous version of this specification
1559   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1560</t>
1561</section>
1562
1563<section title="306 (Unused)" anchor="status.306">
1564  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1565  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1566<t>
1567   The 306 status code was used in a previous version of the
1568   specification, is no longer used, and the code is reserved.
1569</t>
1570</section>
1571
1572<section title="307 Temporary Redirect" anchor="status.307">
1573  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1574  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1575<t>
1576   The target resource resides temporarily under a different URI.
1577   Since the redirection can change over time, the client &SHOULD;
1578   continue to use the effective request URI for future requests.
1579</t>
1580<t>
1581   The temporary URI &SHOULD; be given by the Location field in the
1582   response. Unless the request method was HEAD, the representation of the
1583   response &SHOULD; contain a short hypertext note with a hyperlink to
1584   the new URI(s), since many pre-HTTP/1.1 user agents do not
1585   understand the 307 status code. Therefore, the note &SHOULD; contain the
1586   information necessary for a user to repeat the original request on
1587   the new URI.
1588</t>
1589<t>
1590   If the 307 status code is received in response to a request method
1591   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1592   then the request &MAY; be automatically redirected by the user agent without
1593   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1594   request unless it can be confirmed by the user, since this might
1595   change the conditions under which the request was issued.
1596</t>
1597</section>
1598</section>
1599
1600<section title="Client Error 4xx" anchor="status.4xx">
1601<t>
1602   The 4xx class of status code is intended for cases in which the
1603   client seems to have erred. Except when responding to a HEAD request,
1604   the server &SHOULD; include a representation containing an explanation of the
1605   error situation, and whether it is a temporary or permanent
1606   condition. These status codes are applicable to any request method.
1607   User agents &SHOULD; display any included representation to the user.
1608</t>
1609<t>
1610   If the client is sending data, a server implementation using TCP
1611   &SHOULD; be careful to ensure that the client acknowledges receipt of
1612   the packet(s) containing the response, before the server closes the
1613   input connection. If the client continues sending data to the server
1614   after the close, the server's TCP stack will send a reset packet to
1615   the client, which might erase the client's unacknowledged input buffers
1616   before they can be read and interpreted by the HTTP application.
1617</t>
1618
1619<section title="400 Bad Request" anchor="status.400">
1620  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1621  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1622<t>
1623   The request could not be understood by the server due to malformed
1624   syntax. The client &SHOULD-NOT; repeat the request without
1625   modifications.
1626</t>
1627</section>
1628
1629<section title="401 Unauthorized" anchor="status.401">
1630  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1631  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1632  <rdf:Description>
1633    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part7</redirects-to>
1634  </rdf:Description>
1635<t>
1636   The request requires user authentication (see &status-401;).
1637</t>
1638</section>
1639
1640<section title="402 Payment Required" anchor="status.402">
1641  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1642  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1643<t>
1644   This code is reserved for future use.
1645</t>
1646</section>
1647
1648<section title="403 Forbidden" anchor="status.403">
1649  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1650  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1651<t>
1652   The server understood the request, but is refusing to fulfill it.
1653   Authorization will not help and the request &SHOULD-NOT;  be repeated.
1654   If the request method was not HEAD and the server wishes to make
1655   public why the request has not been fulfilled, it &SHOULD; describe the
1656   reason for the refusal in the representation.  If the server does not wish to
1657   make this information available to the client, the status code 404
1658   (Not Found) can be used instead.
1659</t>
1660</section>
1661
1662<section title="404 Not Found" anchor="status.404">
1663  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1664  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1665<t>
1666   The server has not found anything matching the effective request URI. No
1667   indication is given of whether the condition is temporary or
1668   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1669   knows, through some internally configurable mechanism, that an old
1670   resource is permanently unavailable and has no forwarding address.
1671   This status code is commonly used when the server does not wish to
1672   reveal exactly why the request has been refused, or when no other
1673   response is applicable.
1674</t>
1675</section>
1676
1677<section title="405 Method Not Allowed" anchor="status.405">
1678  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1679  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1680<t>
1681   The method specified in the Request-Line is not allowed for the target
1682   resource. The response &MUST; include an
1683   Allow header field containing a list of valid methods for the requested
1684   resource.
1685</t>
1686</section>
1687
1688<section title="406 Not Acceptable" anchor="status.406">
1689  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1690  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1691<t>
1692   The resource identified by the request is only capable of generating
1693   response representations which have content characteristics not acceptable
1694   according to the accept header fields sent in the request.
1695</t>
1696<t>
1697   Unless it was a HEAD request, the response &SHOULD; include a representation
1698   containing a list of available representation characteristics and location(s)
1699   from which the user or user agent can choose the one most
1700   appropriate. The data format is specified by the media type given
1701   in the Content-Type header field. Depending upon the format and the
1702   capabilities of the user agent, selection of the most appropriate
1703   choice &MAY; be performed automatically. However, this specification
1704   does not define any standard for such automatic selection.
1705</t>
1706<x:note>
1707  <t>
1708    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1709    not acceptable according to the accept header fields sent in the
1710    request. In some cases, this might even be preferable to sending a
1711    406 response. User agents are encouraged to inspect the header fields of
1712    an incoming response to determine if it is acceptable.
1713  </t>
1714</x:note>
1715<t>
1716   If the response could be unacceptable, a user agent &SHOULD;
1717   temporarily stop receipt of more data and query the user for a
1718   decision on further actions.
1719</t>
1720</section>
1721
1722<section title="407 Proxy Authentication Required" anchor="status.407">
1723  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1724  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1725<t>
1726   This code is similar to 401 (Unauthorized), but indicates that the
1727   client must first authenticate itself with the proxy (see &status-407;).
1728</t>
1729</section>
1730
1731<section title="408 Request Timeout" anchor="status.408">
1732  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1733  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1734<t>
1735   The client did not produce a request within the time that the server
1736   was prepared to wait. The client &MAY; repeat the request without
1737   modifications at any later time.
1738</t>
1739</section>
1740
1741<section title="409 Conflict" anchor="status.409">
1742  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1743  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1744<t>
1745   The request could not be completed due to a conflict with the current
1746   state of the resource. This code is only allowed in situations where
1747   it is expected that the user might be able to resolve the conflict
1748   and resubmit the request. The response body &SHOULD; include enough
1749   information for the user to recognize the source of the conflict.
1750   Ideally, the response representation would include enough information for the
1751   user or user agent to fix the problem; however, that might not be
1752   possible and is not required.
1753</t>
1754<t>
1755   Conflicts are most likely to occur in response to a PUT request. For
1756   example, if versioning were being used and the representation being PUT
1757   included changes to a resource which conflict with those made by an
1758   earlier (third-party) request, the server might use the 409 response
1759   to indicate that it can't complete the request. In this case, the
1760   response representation would likely contain a list of the differences
1761   between the two versions in a format defined by the response
1762   Content-Type.
1763</t>
1764</section>
1765
1766<section title="410 Gone" anchor="status.410">
1767  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1768  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1769<t>
1770   The target resource is no longer available at the server and no
1771   forwarding address is known. This condition is expected to be
1772   considered permanent. Clients with link editing capabilities &SHOULD;
1773   delete references to the effective request URI after user approval. If the
1774   server does not know, or has no facility to determine, whether or not
1775   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1776   used instead.
1777</t>
1778<t>
1779   The 410 response is primarily intended to assist the task of web
1780   maintenance by notifying the recipient that the resource is
1781   intentionally unavailable and that the server owners desire that
1782   remote links to that resource be removed. Such an event is common for
1783   limited-time, promotional services and for resources belonging to
1784   individuals no longer working at the server's site. It is not
1785   necessary to mark all permanently unavailable resources as "gone" or
1786   to keep the mark for any length of time -- that is left to the
1787   discretion of the server owner.
1788</t>
1789<t>
1790   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine freshness
1791   for 410 responses.
1792</t>
1793
1794</section>
1795
1796<section title="411 Length Required" anchor="status.411">
1797  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1798  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1799<t>
1800   The server refuses to accept the request without a defined Content-Length.
1801   The client &MAY; repeat the request if it adds a valid
1802   Content-Length header field containing the length of the message-body
1803   in the request message.
1804</t>
1805</section>
1806
1807<section title="412 Precondition Failed" anchor="status.412">
1808  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1809  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1810  <rdf:Description>
1811    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1812  </rdf:Description>
1813<t>
1814   The precondition given in one or more of the request-header fields
1815   evaluated to false when it was tested on the server, as defined in
1816   &status-412;.
1817</t>
1818</section>
1819
1820<section title="413 Request Entity Too Large" anchor="status.413">
1821  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1822  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1823<t>
1824   The server is refusing to process a request because the request
1825   representation is larger than the server is willing or able to process. The
1826   server &MAY; close the connection to prevent the client from continuing
1827   the request.
1828</t>
1829<t>
1830   If the condition is temporary, the server &SHOULD; include a Retry-After
1831   header field to indicate that it is temporary and after what
1832   time the client &MAY; try again.
1833</t>
1834</section>
1835
1836<section title="414 URI Too Long" anchor="status.414">
1837  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1838  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1839<t>
1840   The server is refusing to service the request because the effective request URI
1841   is longer than the server is willing to interpret. This rare
1842   condition is only likely to occur when a client has improperly
1843   converted a POST request to a GET request with long query
1844   information, when the client has descended into a URI "black hole" of
1845   redirection (e.g., a redirected URI prefix that points to a suffix of
1846   itself), or when the server is under attack by a client attempting to
1847   exploit security holes present in some servers using fixed-length
1848   buffers for reading or manipulating the effective request URI.
1849</t>
1850</section>
1851
1852<section title="415 Unsupported Media Type" anchor="status.415">
1853  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1854  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1855<t>
1856   The server is refusing to service the request because the representation of
1857   the request is in a format not supported by the target resource
1858   for the requested method.
1859</t>
1860</section>
1861
1862<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1863  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1864  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1865  <rdf:Description>
1866    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1867  </rdf:Description>
1868<t>
1869   The request included a Range request-header field (&header-range;) and none of
1870   the range-specifier values in this field overlap the current extent
1871   of the selected resource. See &status-416;.
1872</t>
1873</section>
1874
1875<section title="417 Expectation Failed" anchor="status.417">
1876  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
1877  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
1878<t>
1879   The expectation given in an Expect request-header field (see <xref target="header.expect"/>)
1880   could not be met by this server, or, if the server is a proxy,
1881   the server has unambiguous evidence that the request could not be met
1882   by the next-hop server.
1883</t>
1884</section>
1885</section>
1886
1887<section title="Server Error 5xx" anchor="status.5xx">
1888<t>
1889   Response status codes beginning with the digit "5" indicate cases in
1890   which the server is aware that it has erred or is incapable of
1891   performing the request. Except when responding to a HEAD request, the
1892   server &SHOULD; include a representation containing an explanation of the
1893   error situation, and whether it is a temporary or permanent
1894   condition. User agents &SHOULD; display any included representation to the
1895   user. These response codes are applicable to any request method.
1896</t>
1897
1898<section title="500 Internal Server Error" anchor="status.500">
1899  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
1900  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
1901<t>
1902   The server encountered an unexpected condition which prevented it
1903   from fulfilling the request.
1904</t>
1905</section>
1906
1907<section title="501 Not Implemented" anchor="status.501">
1908  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
1909  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
1910<t>
1911   The server does not support the functionality required to fulfill the
1912   request. This is the appropriate response when the server does not
1913   recognize the request method and is not capable of supporting it for
1914   any resource.
1915</t>
1916</section>
1917
1918<section title="502 Bad Gateway" anchor="status.502">
1919  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
1920  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
1921<t>
1922   The server, while acting as a gateway or proxy, received an invalid
1923   response from the upstream server it accessed in attempting to
1924   fulfill the request.
1925</t>
1926</section>
1927
1928<section title="503 Service Unavailable" anchor="status.503">
1929  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
1930  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
1931<t>
1932   The server is currently unable to handle the request due to a
1933   temporary overloading or maintenance of the server. The implication
1934   is that this is a temporary condition which will be alleviated after
1935   some delay. If known, the length of the delay &MAY; be indicated in a
1936   Retry-After header field. If no Retry-After is given, the client &SHOULD;
1937   handle the response as it would for a 500 response.
1938</t>
1939<x:note>
1940  <t>
1941    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
1942    server must use it when becoming overloaded. Some servers might wish
1943    to simply refuse the connection.
1944  </t>
1945</x:note>
1946</section>
1947
1948<section title="504 Gateway Timeout" anchor="status.504">
1949  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
1950  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
1951<t>
1952   The server, while acting as a gateway or proxy, did not receive a
1953   timely response from the upstream server specified by the URI (e.g.,
1954   HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
1955   to access in attempting to complete the request.
1956</t>
1957<x:note>
1958  <t>
1959    <x:h>Note</x:h> to implementors: some deployed proxies are known to
1960    return 400 or 500 when DNS lookups time out.
1961  </t>
1962</x:note>
1963</section>
1964
1965<section title="505 HTTP Version Not Supported" anchor="status.505">
1966  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
1967  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
1968<t>
1969   The server does not support, or refuses to support, the protocol
1970   version that was used in the request message. The server is
1971   indicating that it is unable or unwilling to complete the request
1972   using the same major version as the client, as described in &http-version;,
1973   other than with this error message. The response &SHOULD; contain
1974   a representation describing why that version is not supported and what other
1975   protocols are supported by that server.
1976</t>
1977
1978</section>
1979</section>
1980</section>
1981
1982
1983<section title="Header Field Definitions" anchor="header.fields">
1984<t>
1985   This section defines the syntax and semantics of HTTP/1.1 header fields
1986   related to request and response semantics.
1987</t>
1988
1989<section title="Allow" anchor="header.allow">
1990  <iref primary="true" item="Allow header" x:for-anchor=""/>
1991  <iref primary="true" item="Headers" subitem="Allow" x:for-anchor=""/>
1992  <x:anchor-alias value="Allow"/>
1993  <x:anchor-alias value="Allow-v"/>
1994<t>
1995   The "Allow" response-header field lists the set of methods advertised as
1996   supported by the target resource. The purpose of
1997   this field is strictly to inform the recipient of valid methods
1998   associated with the resource.
1999</t>
2000<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/><iref primary="true" item="Grammar" subitem="Allow-v"/>
2001  <x:ref>Allow</x:ref>   = "Allow" ":" <x:ref>OWS</x:ref> <x:ref>Allow-v</x:ref>
2002  <x:ref>Allow-v</x:ref> = #<x:ref>Method</x:ref>
2003</artwork></figure>
2004<t>
2005      Example of use:
2006</t>
2007<figure><artwork type="example">
2008  Allow: GET, HEAD, PUT
2009</artwork></figure>
2010<t>
2011      The actual set of allowed methods is defined
2012      by the origin server at the time of each request.
2013</t>
2014<t>
2015      A proxy &MUST-NOT; modify the Allow header field even if it does not
2016      understand all the methods specified, since the user agent might
2017      have other means of communicating with the origin server.
2018</t>
2019</section>
2020
2021<section title="Expect" anchor="header.expect">
2022  <iref primary="true" item="Expect header" x:for-anchor=""/>
2023  <iref primary="true" item="Headers" subitem="Expect" x:for-anchor=""/>
2024  <x:anchor-alias value="Expect"/>
2025  <x:anchor-alias value="Expect-v"/>
2026  <x:anchor-alias value="expectation"/>
2027  <x:anchor-alias value="expectation-extension"/>
2028  <x:anchor-alias value="expect-params"/>
2029<t>
2030   The "Expect" request-header field is used to indicate that particular
2031   server behaviors are required by the client.
2032</t>
2033<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"/>
2034  <x:ref>Expect</x:ref>       = "Expect" ":" <x:ref>OWS</x:ref> <x:ref>Expect-v</x:ref>
2035  <x:ref>Expect-v</x:ref>     = 1#<x:ref>expectation</x:ref>
2036 
2037  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
2038  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
2039                           *<x:ref>expect-params</x:ref> ]
2040  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
2041</artwork></figure>
2042<t>
2043   A server that does not understand or is unable to comply with any of
2044   the expectation values in the Expect field of a request &MUST; respond
2045   with appropriate error status code. The server &MUST; respond with a 417
2046   (Expectation Failed) status code if any of the expectations cannot be met
2047   or, if there are other problems with the request, some other 4xx
2048   status code.
2049</t>
2050<t>
2051   This header field is defined with extensible syntax to allow for
2052   future extensions. If a server receives a request containing an
2053   Expect field that includes an expectation-extension that it does not
2054   support, it &MUST; respond with a 417 (Expectation Failed) status code.
2055</t>
2056<t>
2057   Comparison of expectation values is case-insensitive for unquoted
2058   tokens (including the 100-continue token), and is case-sensitive for
2059   quoted-string expectation-extensions.
2060</t>
2061<t>
2062   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
2063   return a 417 (Expectation Failed) status code if it receives a request
2064   with an expectation that it cannot meet. However, the Expect
2065   request-header field itself is end-to-end; it &MUST; be forwarded if the
2066   request is forwarded.
2067</t>
2068<t>
2069   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
2070   Expect header field.
2071</t>
2072<t>
2073   See &use100; for the use of the 100 (Continue) status code.
2074</t>
2075</section>
2076
2077<section title="From" anchor="header.from">
2078  <iref primary="true" item="From header" x:for-anchor=""/>
2079  <iref primary="true" item="Headers" subitem="From" x:for-anchor=""/>
2080  <x:anchor-alias value="From"/>
2081  <x:anchor-alias value="From-v"/>
2082  <x:anchor-alias value="mailbox"/>
2083<t>
2084   The "From" request-header field, if given, &SHOULD; contain an Internet
2085   e-mail address for the human user who controls the requesting user
2086   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
2087   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
2088</t>
2089<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/><iref primary="true" item="Grammar" subitem="From-v"/>
2090  <x:ref>From</x:ref>    = "From" ":" <x:ref>OWS</x:ref> <x:ref>From-v</x:ref>
2091  <x:ref>From-v</x:ref>  = <x:ref>mailbox</x:ref>
2092 
2093  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
2094</artwork></figure>
2095<t>
2096   An example is:
2097</t>
2098<figure><artwork type="example">
2099  From: webmaster@example.org
2100</artwork></figure>
2101<t>
2102   This header field &MAY; be used for logging purposes and as a means for
2103   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
2104   be used as an insecure form of access protection. The interpretation
2105   of this field is that the request is being performed on behalf of the
2106   person given, who accepts responsibility for the method performed. In
2107   particular, robot agents &SHOULD; include this header field so that the
2108   person responsible for running the robot can be contacted if problems
2109   occur on the receiving end.
2110</t>
2111<t>
2112   The Internet e-mail address in this field &MAY; be separate from the
2113   Internet host which issued the request. For example, when a request
2114   is passed through a proxy the original issuer's address &SHOULD; be
2115   used.
2116</t>
2117<t>
2118   The client &SHOULD-NOT;  send the From header field without the user's
2119   approval, as it might conflict with the user's privacy interests or
2120   their site's security policy. It is strongly recommended that the
2121   user be able to disable, enable, and modify the value of this field
2122   at any time prior to a request.
2123</t>
2124</section>
2125
2126<section title="Location" anchor="header.location">
2127  <iref primary="true" item="Location header" x:for-anchor=""/>
2128  <iref primary="true" item="Headers" subitem="Location" x:for-anchor=""/>
2129  <x:anchor-alias value="Location"/>
2130  <x:anchor-alias value="Location-v"/>
2131<t>
2132   The "Location" response-header field is used to identify a newly created
2133   resource, or to redirect the recipient to a different location for
2134   completion of the request.
2135</t>
2136<t>
2137   For 201 (Created) responses, the Location is the URI of the new resource
2138   which was created by the request. For 3xx responses, the location &SHOULD;
2139   indicate the server's preferred URI for automatic redirection to the
2140   resource.
2141</t>
2142<t>
2143   The field value consists of a single URI-reference. When it has the form
2144   of a relative reference (<xref target="RFC3986" x:fmt="," x:sec="4.2"/>),
2145   the final value is computed by resolving it against the effective request
2146   URI (<xref target="RFC3986" x:fmt="," x:sec="5"/>).
2147</t>
2148<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/><iref primary="true" item="Grammar" subitem="Location-v"/>
2149  <x:ref>Location</x:ref>       = "Location" ":" <x:ref>OWS</x:ref> <x:ref>Location-v</x:ref>
2150  <x:ref>Location-v</x:ref>     = <x:ref>URI-reference</x:ref>
2151</artwork></figure>
2152<figure>
2153<preamble>Examples are:</preamble><!--DO NOT DARE changing the vertical WSP below, it's necessary this way for xml2rfc-->
2154<artwork type="example">
2155  Location: http://www.example.org/pub/WWW/People.html#tim
2156</artwork></figure><figure><artwork type="example">  Location: /index.html
2157</artwork></figure>
2158<t>
2159   There are circumstances in which a fragment identifier in a Location URI
2160   would not be appropriate:
2161   <list style="symbols">
2162      <t>With a 201 Created response, because in this usage the Location header
2163      field specifies the URI for the entire created resource.</t>
2164      <t>With 305 Use Proxy.</t>
2165   </list>
2166</t>
2167<x:note>
2168  <t>
2169    <x:h>Note:</x:h> This specification does not define precedence rules
2170    for the case where the original URI, as navigated to by the user
2171    agent, and the Location header field value both contain fragment
2172    identifiers.
2173  </t>
2174</x:note>
2175<x:note>
2176  <t>
2177    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2178    from Location in that the Content-Location identifies the most specific
2179    resource corresponding to the enclosed representation.
2180    It is therefore possible for a response to contain header fields for
2181    both Location and Content-Location.
2182  </t>
2183</x:note>
2184</section>
2185
2186<section title="Max-Forwards" anchor="header.max-forwards">
2187  <iref primary="true" item="Max-Forwards header" x:for-anchor=""/>
2188  <iref primary="true" item="Headers" subitem="Max-Forwards" x:for-anchor=""/>
2189  <x:anchor-alias value="Max-Forwards"/>
2190  <x:anchor-alias value="Max-Forwards-v"/>
2191<t>
2192   The "Max-Forwards" request-header field provides a mechanism with the
2193   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>)
2194   methods to limit the number of times that the request is forwarded by
2195   proxies or gateways. This can be useful when the client is attempting to
2196   trace a request which appears to be failing or looping in mid-chain.
2197</t>
2198<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/><iref primary="true" item="Grammar" subitem="Max-Forwards-v"/>
2199  <x:ref>Max-Forwards</x:ref>   = "Max-Forwards" ":" <x:ref>OWS</x:ref> <x:ref>Max-Forwards-v</x:ref>
2200  <x:ref>Max-Forwards-v</x:ref> = 1*<x:ref>DIGIT</x:ref>
2201</artwork></figure>
2202<t>
2203   The Max-Forwards value is a decimal integer indicating the remaining
2204   number of times this request message can be forwarded.
2205</t>
2206<t>
2207   Each proxy or gateway recipient of a TRACE or OPTIONS request
2208   containing a Max-Forwards header field &MUST; check and update its
2209   value prior to forwarding the request. If the received value is zero
2210   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2211   respond as the final recipient. If the received Max-Forwards value is
2212   greater than zero, then the forwarded message &MUST; contain an updated
2213   Max-Forwards field with a value decremented by one (1).
2214</t>
2215<t>
2216   The Max-Forwards header field &MAY; be ignored for all other methods
2217   defined by this specification and for any extension methods for which
2218   it is not explicitly referred to as part of that method definition.
2219</t>
2220</section>
2221
2222<section title="Referer" anchor="header.referer">
2223  <iref primary="true" item="Referer header" x:for-anchor=""/>
2224  <iref primary="true" item="Headers" subitem="Referer" x:for-anchor=""/>
2225  <x:anchor-alias value="Referer"/>
2226  <x:anchor-alias value="Referer-v"/>
2227<t>
2228   The "Referer" [sic] request-header field allows the client to specify the
2229   URI of the resource from which the effective request URI was obtained (the
2230   "referrer", although the header field is misspelled.).
2231</t>
2232<t>
2233   The Referer header field allows servers to generate lists of back-links to
2234   resources for interest, logging, optimized caching, etc. It also allows
2235   obsolete or mistyped links to be traced for maintenance. Some servers use
2236   Referer as a means of controlling where they allow links from (so-called
2237   "deep linking"), but legitimate requests do not always
2238   contain a Referer header field.
2239</t>
2240<t>
2241   If the effective request URI was obtained from a source that does not have its own
2242   URI (e.g., input from the user keyboard), the Referer field &MUST; either be
2243   sent with the value "about:blank", or not be sent at all. Note that this
2244   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2245</t>
2246<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/><iref primary="true" item="Grammar" subitem="Referer-v"/>
2247  <x:ref>Referer</x:ref>        = "Referer" ":" <x:ref>OWS</x:ref> <x:ref>Referer-v</x:ref>
2248  <x:ref>Referer-v</x:ref>      = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2249</artwork></figure>
2250<t>
2251   Example:
2252</t>
2253<figure><artwork type="example">
2254  Referer: http://www.example.org/hypertext/Overview.html
2255</artwork></figure>
2256<t>
2257   If the field value is a relative URI, it &SHOULD; be interpreted
2258   relative to the effective request URI. The URI &MUST-NOT; include a fragment. See
2259   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2260</t>
2261</section>
2262
2263<section title="Retry-After" anchor="header.retry-after">
2264  <iref primary="true" item="Retry-After header" x:for-anchor=""/>
2265  <iref primary="true" item="Headers" subitem="Retry-After" x:for-anchor=""/>
2266  <x:anchor-alias value="Retry-After"/>
2267  <x:anchor-alias value="Retry-After-v"/>
2268<t>
2269   The response-header "Retry-After" field can be used with a 503 (Service
2270   Unavailable) response to indicate how long the service is expected to
2271   be unavailable to the requesting client. This field &MAY; also be used
2272   with any 3xx (Redirection) response to indicate the minimum time the
2273   user-agent is asked wait before issuing the redirected request.
2274</t>
2275<t>
2276   The value of this field can be either an HTTP-date or an integer number
2277   of seconds (in decimal) after the time of the response.
2278</t>
2279<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/><iref primary="true" item="Grammar" subitem="Retry-After-v"/>
2280  <x:ref>Retry-After</x:ref>   = "Retry-After" ":" <x:ref>OWS</x:ref> <x:ref>Retry-After-v</x:ref>
2281  <x:ref>Retry-After-v</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2282</artwork></figure>
2283<t anchor="rule.delta-seconds">
2284  <x:anchor-alias value="delta-seconds"/>
2285   Time spans are non-negative decimal integers, representing time in
2286   seconds.
2287</t>
2288<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2289  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2290</artwork></figure>
2291<t>
2292   Two examples of its use are
2293</t>
2294<figure><artwork type="example">
2295  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2296  Retry-After: 120
2297</artwork></figure>
2298<t>
2299   In the latter example, the delay is 2 minutes.
2300</t>
2301</section>
2302
2303<section title="Server" anchor="header.server">
2304  <iref primary="true" item="Server header" x:for-anchor=""/>
2305  <iref primary="true" item="Headers" subitem="Server" x:for-anchor=""/>
2306  <x:anchor-alias value="Server"/>
2307  <x:anchor-alias value="Server-v"/>
2308<t>
2309   The "Server" response-header field contains information about the
2310   software used by the origin server to handle the request.
2311</t>
2312<t>
2313   The field can contain multiple product tokens (&product-tokens;) and
2314   comments (&header-fields;) identifying the server and any significant
2315   subproducts. The product tokens are listed in order of their significance
2316   for identifying the application.
2317</t>
2318<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/><iref primary="true" item="Grammar" subitem="Server-v"/>
2319  <x:ref>Server</x:ref>         = "Server" ":" <x:ref>OWS</x:ref> <x:ref>Server-v</x:ref>
2320  <x:ref>Server-v</x:ref>       = <x:ref>product</x:ref>
2321                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2322</artwork></figure>
2323<t>
2324   Example:
2325</t>
2326<figure><artwork type="example">
2327  Server: CERN/3.0 libwww/2.17
2328</artwork></figure>
2329<t>
2330   If the response is being forwarded through a proxy, the proxy
2331   application &MUST-NOT; modify the Server response-header field. Instead, it
2332   &MUST; include a Via field (as described in &header-via;).
2333</t>
2334<x:note>
2335  <t>
2336    <x:h>Note:</x:h> Revealing the specific software version of the server might
2337    allow the server machine to become more vulnerable to attacks
2338    against software that is known to contain security holes. Server
2339    implementors are encouraged to make this field a configurable
2340    option.
2341  </t>
2342</x:note>
2343</section>
2344
2345<section title="User-Agent" anchor="header.user-agent">
2346  <iref primary="true" item="User-Agent header" x:for-anchor=""/>
2347  <iref primary="true" item="Headers" subitem="User-Agent" x:for-anchor=""/>
2348  <x:anchor-alias value="User-Agent"/>
2349  <x:anchor-alias value="User-Agent-v"/>
2350<t>
2351   The "User-Agent" request-header field contains information about the user
2352   agent originating the request. User agents &SHOULD; include this field with
2353   requests.
2354</t>
2355<t>
2356   Typically, it is used for statistical purposes, the tracing of protocol
2357   violations, and tailoring responses to avoid particular user agent
2358   limitations.
2359</t>
2360<t>
2361   The field can contain multiple product tokens (&product-tokens;)
2362   and comments (&header-fields;) identifying the agent and its
2363   significant subproducts. By convention, the product tokens are listed in
2364   order of their significance for identifying the application.
2365</t>
2366<t>
2367   Because this field is usually sent on every request a user agent makes,
2368   implementations are encouraged not to include needlessly fine-grained
2369   detail, and to limit (or even prohibit) the addition of subproducts by third
2370   parties. Overly long and detailed User-Agent field values make requests
2371   larger and can also be used to identify ("fingerprint") the user against
2372   their wishes.
2373</t>
2374<t>
2375   Likewise, implementations are encouraged not to use the product tokens of
2376   other implementations in order to declare compatibility with them, as this
2377   circumvents the purpose of the field. Finally, they are encouraged not to
2378   use comments to identify products; doing so makes the field value more
2379   difficult to parse.
2380</t>
2381<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/><iref primary="true" item="Grammar" subitem="User-Agent-v"/>
2382  <x:ref>User-Agent</x:ref>     = "User-Agent" ":" <x:ref>OWS</x:ref> <x:ref>User-Agent-v</x:ref>
2383  <x:ref>User-Agent-v</x:ref>   = <x:ref>product</x:ref>
2384                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2385</artwork></figure>
2386<t>
2387   Example:
2388</t>
2389<figure><artwork type="example">
2390  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2391</artwork></figure>
2392</section>
2393
2394</section>
2395
2396<section title="IANA Considerations" anchor="IANA.considerations">
2397
2398<section title="Method Registry" anchor="method.registration">
2399<t>
2400  The registration procedure for HTTP Methods is defined by
2401  <xref target="method.registry"/> of this document.
2402</t>
2403<t>
2404   The HTTP Method Registry shall be created at <eref target="http://www.iana.org/assignments/http-methods"/>
2405   and be populated with the registrations below:
2406</t>
2407<?BEGININC p2-semantics.iana-methods ?>
2408<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2409<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2410   <ttcol>Method</ttcol>
2411   <ttcol>Safe</ttcol>
2412   <ttcol>Reference</ttcol>
2413   <c>CONNECT</c>
2414   <c>no</c>
2415   <c>
2416      <xref target="CONNECT"/>
2417   </c>
2418   <c>DELETE</c>
2419   <c>no</c>
2420   <c>
2421      <xref target="DELETE"/>
2422   </c>
2423   <c>GET</c>
2424   <c>yes</c>
2425   <c>
2426      <xref target="GET"/>
2427   </c>
2428   <c>HEAD</c>
2429   <c>yes</c>
2430   <c>
2431      <xref target="HEAD"/>
2432   </c>
2433   <c>OPTIONS</c>
2434   <c>yes</c>
2435   <c>
2436      <xref target="OPTIONS"/>
2437   </c>
2438   <c>POST</c>
2439   <c>no</c>
2440   <c>
2441      <xref target="POST"/>
2442   </c>
2443   <c>PUT</c>
2444   <c>no</c>
2445   <c>
2446      <xref target="PUT"/>
2447   </c>
2448   <c>TRACE</c>
2449   <c>yes</c>
2450   <c>
2451      <xref target="TRACE"/>
2452   </c>
2453</texttable>
2454<!--(END)-->
2455<?ENDINC p2-semantics.iana-methods ?>
2456</section>
2457
2458<section title="Status Code Registry" anchor="status.code.registration">
2459<t>
2460   The registration procedure for HTTP Status Codes -- previously defined
2461   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> -- is now defined
2462   by <xref target="status.code.registry"/> of this document.
2463</t>
2464<t>
2465   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2466   shall be updated with the registrations below:
2467</t>
2468<?BEGININC p2-semantics.iana-status-codes ?>
2469<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2470<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2471   <ttcol>Value</ttcol>
2472   <ttcol>Description</ttcol>
2473   <ttcol>Reference</ttcol>
2474   <c>100</c>
2475   <c>Continue</c>
2476   <c>
2477      <xref target="status.100"/>
2478   </c>
2479   <c>101</c>
2480   <c>Switching Protocols</c>
2481   <c>
2482      <xref target="status.101"/>
2483   </c>
2484   <c>200</c>
2485   <c>OK</c>
2486   <c>
2487      <xref target="status.200"/>
2488   </c>
2489   <c>201</c>
2490   <c>Created</c>
2491   <c>
2492      <xref target="status.201"/>
2493   </c>
2494   <c>202</c>
2495   <c>Accepted</c>
2496   <c>
2497      <xref target="status.202"/>
2498   </c>
2499   <c>203</c>
2500   <c>Non-Authoritative Information</c>
2501   <c>
2502      <xref target="status.203"/>
2503   </c>
2504   <c>204</c>
2505   <c>No Content</c>
2506   <c>
2507      <xref target="status.204"/>
2508   </c>
2509   <c>205</c>
2510   <c>Reset Content</c>
2511   <c>
2512      <xref target="status.205"/>
2513   </c>
2514   <c>300</c>
2515   <c>Multiple Choices</c>
2516   <c>
2517      <xref target="status.300"/>
2518   </c>
2519   <c>301</c>
2520   <c>Moved Permanently</c>
2521   <c>
2522      <xref target="status.301"/>
2523   </c>
2524   <c>302</c>
2525   <c>Found</c>
2526   <c>
2527      <xref target="status.302"/>
2528   </c>
2529   <c>303</c>
2530   <c>See Other</c>
2531   <c>
2532      <xref target="status.303"/>
2533   </c>
2534   <c>305</c>
2535   <c>Use Proxy</c>
2536   <c>
2537      <xref target="status.305"/>
2538   </c>
2539   <c>306</c>
2540   <c>(Unused)</c>
2541   <c>
2542      <xref target="status.306"/>
2543   </c>
2544   <c>307</c>
2545   <c>Temporary Redirect</c>
2546   <c>
2547      <xref target="status.307"/>
2548   </c>
2549   <c>400</c>
2550   <c>Bad Request</c>
2551   <c>
2552      <xref target="status.400"/>
2553   </c>
2554   <c>402</c>
2555   <c>Payment Required</c>
2556   <c>
2557      <xref target="status.402"/>
2558   </c>
2559   <c>403</c>
2560   <c>Forbidden</c>
2561   <c>
2562      <xref target="status.403"/>
2563   </c>
2564   <c>404</c>
2565   <c>Not Found</c>
2566   <c>
2567      <xref target="status.404"/>
2568   </c>
2569   <c>405</c>
2570   <c>Method Not Allowed</c>
2571   <c>
2572      <xref target="status.405"/>
2573   </c>
2574   <c>406</c>
2575   <c>Not Acceptable</c>
2576   <c>
2577      <xref target="status.406"/>
2578   </c>
2579   <c>407</c>
2580   <c>Proxy Authentication Required</c>
2581   <c>
2582      <xref target="status.407"/>
2583   </c>
2584   <c>408</c>
2585   <c>Request Timeout</c>
2586   <c>
2587      <xref target="status.408"/>
2588   </c>
2589   <c>409</c>
2590   <c>Conflict</c>
2591   <c>
2592      <xref target="status.409"/>
2593   </c>
2594   <c>410</c>
2595   <c>Gone</c>
2596   <c>
2597      <xref target="status.410"/>
2598   </c>
2599   <c>411</c>
2600   <c>Length Required</c>
2601   <c>
2602      <xref target="status.411"/>
2603   </c>
2604   <c>413</c>
2605   <c>Request Entity Too Large</c>
2606   <c>
2607      <xref target="status.413"/>
2608   </c>
2609   <c>414</c>
2610   <c>URI Too Long</c>
2611   <c>
2612      <xref target="status.414"/>
2613   </c>
2614   <c>415</c>
2615   <c>Unsupported Media Type</c>
2616   <c>
2617      <xref target="status.415"/>
2618   </c>
2619   <c>417</c>
2620   <c>Expectation Failed</c>
2621   <c>
2622      <xref target="status.417"/>
2623   </c>
2624   <c>500</c>
2625   <c>Internal Server Error</c>
2626   <c>
2627      <xref target="status.500"/>
2628   </c>
2629   <c>501</c>
2630   <c>Not Implemented</c>
2631   <c>
2632      <xref target="status.501"/>
2633   </c>
2634   <c>502</c>
2635   <c>Bad Gateway</c>
2636   <c>
2637      <xref target="status.502"/>
2638   </c>
2639   <c>503</c>
2640   <c>Service Unavailable</c>
2641   <c>
2642      <xref target="status.503"/>
2643   </c>
2644   <c>504</c>
2645   <c>Gateway Timeout</c>
2646   <c>
2647      <xref target="status.504"/>
2648   </c>
2649   <c>505</c>
2650   <c>HTTP Version Not Supported</c>
2651   <c>
2652      <xref target="status.505"/>
2653   </c>
2654</texttable>
2655<!--(END)-->
2656<?ENDINC p2-semantics.iana-status-codes ?>
2657</section>
2658<section title="Header Field Registration" anchor="header.field.registration">
2659<t>
2660   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
2661   with the permanent registrations below (see <xref target="RFC3864"/>):
2662</t>
2663<?BEGININC p2-semantics.iana-headers ?>
2664<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2665<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2666   <ttcol>Header Field Name</ttcol>
2667   <ttcol>Protocol</ttcol>
2668   <ttcol>Status</ttcol>
2669   <ttcol>Reference</ttcol>
2670
2671   <c>Allow</c>
2672   <c>http</c>
2673   <c>standard</c>
2674   <c>
2675      <xref target="header.allow"/>
2676   </c>
2677   <c>Expect</c>
2678   <c>http</c>
2679   <c>standard</c>
2680   <c>
2681      <xref target="header.expect"/>
2682   </c>
2683   <c>From</c>
2684   <c>http</c>
2685   <c>standard</c>
2686   <c>
2687      <xref target="header.from"/>
2688   </c>
2689   <c>Location</c>
2690   <c>http</c>
2691   <c>standard</c>
2692   <c>
2693      <xref target="header.location"/>
2694   </c>
2695   <c>Max-Forwards</c>
2696   <c>http</c>
2697   <c>standard</c>
2698   <c>
2699      <xref target="header.max-forwards"/>
2700   </c>
2701   <c>Referer</c>
2702   <c>http</c>
2703   <c>standard</c>
2704   <c>
2705      <xref target="header.referer"/>
2706   </c>
2707   <c>Retry-After</c>
2708   <c>http</c>
2709   <c>standard</c>
2710   <c>
2711      <xref target="header.retry-after"/>
2712   </c>
2713   <c>Server</c>
2714   <c>http</c>
2715   <c>standard</c>
2716   <c>
2717      <xref target="header.server"/>
2718   </c>
2719   <c>User-Agent</c>
2720   <c>http</c>
2721   <c>standard</c>
2722   <c>
2723      <xref target="header.user-agent"/>
2724   </c>
2725</texttable>
2726<!--(END)-->
2727<?ENDINC p2-semantics.iana-headers ?>
2728<t>
2729   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2730</t>
2731</section>
2732</section>
2733
2734<section title="Security Considerations" anchor="security.considerations">
2735<t>
2736   This section is meant to inform application developers, information
2737   providers, and users of the security limitations in HTTP/1.1 as
2738   described by this document. The discussion does not include
2739   definitive solutions to the problems revealed, though it does make
2740   some suggestions for reducing security risks.
2741</t>
2742
2743<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2744<t>
2745   Like any generic data transfer protocol, HTTP cannot regulate the
2746   content of the data that is transferred, nor is there any a priori
2747   method of determining the sensitivity of any particular piece of
2748   information within the context of any given request. Therefore,
2749   applications &SHOULD; supply as much control over this information as
2750   possible to the provider of that information. Four header fields are
2751   worth special mention in this context: Server, Via, Referer and From.
2752</t>
2753<t>
2754   Revealing the specific software version of the server might allow the
2755   server machine to become more vulnerable to attacks against software
2756   that is known to contain security holes. Implementors &SHOULD; make the
2757   Server header field a configurable option.
2758</t>
2759<t>
2760   Proxies which serve as a portal through a network firewall &SHOULD;
2761   take special precautions regarding the transfer of header information
2762   that identifies the hosts behind the firewall. In particular, they
2763   &SHOULD; remove, or replace with sanitized versions, any Via fields
2764   generated behind the firewall.
2765</t>
2766<t>
2767   The Referer header field allows reading patterns to be studied and reverse
2768   links drawn. Although it can be very useful, its power can be abused
2769   if user details are not separated from the information contained in
2770   the Referer. Even when the personal information has been removed, the
2771   Referer header field might indicate a private document's URI whose
2772   publication would be inappropriate.
2773</t>
2774<t>
2775   The information sent in the From field might conflict with the user's
2776   privacy interests or their site's security policy, and hence it
2777   &SHOULD-NOT;  be transmitted without the user being able to disable,
2778   enable, and modify the contents of the field. The user &MUST; be able
2779   to set the contents of this field within a user preference or
2780   application defaults configuration.
2781</t>
2782<t>
2783   We suggest, though do not require, that a convenient toggle interface
2784   be provided for the user to enable or disable the sending of From and
2785   Referer information.
2786</t>
2787<t>
2788   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref
2789   target="header.server"/>) header fields can sometimes be used to determine
2790   that a specific client or server have a particular security hole which might
2791   be exploited. Unfortunately, this same information is often used for other
2792   valuable purposes for which HTTP currently has no better mechanism.
2793</t>
2794<t>
2795   Furthermore, the User-Agent header field may contain enough entropy to be
2796   used, possibly in conjunction with other material, to uniquely identify the
2797   user.
2798</t>
2799<t>
2800   Some methods, like TRACE (<xref target="TRACE"/>), expose information
2801   that was sent in request header fields within the body of their response.
2802   Clients &SHOULD; be careful with sensitive information, like Cookies,
2803   Authorization credentials and other header fields that might be used to
2804   collect data from the client.
2805</t> 
2806</section>
2807
2808<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2809<t>
2810   Because the source of a link might be private information or might
2811   reveal an otherwise private information source, it is strongly
2812   recommended that the user be able to select whether or not the
2813   Referer field is sent. For example, a browser client could have a
2814   toggle switch for browsing openly/anonymously, which would
2815   respectively enable/disable the sending of Referer and From
2816   information.
2817</t>
2818<t>
2819   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2820   HTTP request if the referring page was transferred with a secure
2821   protocol.
2822</t>
2823<t>
2824   Authors of services &SHOULD-NOT; use GET-based forms for the submission of
2825   sensitive data because that data will be placed in the request-target. Many
2826   existing servers, proxies, and user agents log or display the request-target
2827   in places where it might be visible to third parties. Such services can
2828   use POST-based form submission instead.
2829</t>
2830</section>
2831
2832<section title="Location Headers and Spoofing" anchor="location.spoofing">
2833<t>
2834   If a single server supports multiple organizations that do not trust
2835   one another, then it &MUST; check the values of Location and Content-Location
2836   header fields in responses that are generated under control of
2837   said organizations to make sure that they do not attempt to
2838   invalidate resources over which they have no authority.
2839</t>
2840</section>
2841
2842</section>
2843
2844<section title="Acknowledgments" anchor="ack">
2845</section>
2846</middle>
2847<back>
2848
2849<references title="Normative References">
2850
2851<reference anchor="Part1">
2852  <front>
2853    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2854    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2855      <organization abbrev="Day Software">Day Software</organization>
2856      <address><email>fielding@gbiv.com</email></address>
2857    </author>
2858    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2859      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2860      <address><email>jg@freedesktop.org</email></address>
2861    </author>
2862    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2863      <organization abbrev="HP">Hewlett-Packard Company</organization>
2864      <address><email>JeffMogul@acm.org</email></address>
2865    </author>
2866    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2867      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2868      <address><email>henrikn@microsoft.com</email></address>
2869    </author>
2870    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2871      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2872      <address><email>LMM@acm.org</email></address>
2873    </author>
2874    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2875      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2876      <address><email>paulle@microsoft.com</email></address>
2877    </author>
2878    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2879      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2880      <address><email>timbl@w3.org</email></address>
2881    </author>
2882    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2883      <organization abbrev="W3C">World Wide Web Consortium</organization>
2884      <address><email>ylafon@w3.org</email></address>
2885    </author>
2886    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2887      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2888      <address><email>julian.reschke@greenbytes.de</email></address>
2889    </author>
2890    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2891  </front>
2892  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
2893  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
2894</reference>
2895
2896<reference anchor="Part3">
2897  <front>
2898    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
2899    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2900      <organization abbrev="Day Software">Day Software</organization>
2901      <address><email>fielding@gbiv.com</email></address>
2902    </author>
2903    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2904      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2905      <address><email>jg@freedesktop.org</email></address>
2906    </author>
2907    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2908      <organization abbrev="HP">Hewlett-Packard Company</organization>
2909      <address><email>JeffMogul@acm.org</email></address>
2910    </author>
2911    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2912      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2913      <address><email>henrikn@microsoft.com</email></address>
2914    </author>
2915    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2916      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2917      <address><email>LMM@acm.org</email></address>
2918    </author>
2919    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2920      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2921      <address><email>paulle@microsoft.com</email></address>
2922    </author>
2923    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2924      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2925      <address><email>timbl@w3.org</email></address>
2926    </author>
2927    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2928      <organization abbrev="W3C">World Wide Web Consortium</organization>
2929      <address><email>ylafon@w3.org</email></address>
2930    </author>
2931    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2932      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2933      <address><email>julian.reschke@greenbytes.de</email></address>
2934    </author>
2935    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2936  </front>
2937  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
2938  <x:source href="p3-payload.xml" basename="p3-payload"/>
2939</reference>
2940
2941<reference anchor="Part4">
2942  <front>
2943    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
2944    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2945      <organization abbrev="Day Software">Day Software</organization>
2946      <address><email>fielding@gbiv.com</email></address>
2947    </author>
2948    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2949      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2950      <address><email>jg@freedesktop.org</email></address>
2951    </author>
2952    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2953      <organization abbrev="HP">Hewlett-Packard Company</organization>
2954      <address><email>JeffMogul@acm.org</email></address>
2955    </author>
2956    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2957      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2958      <address><email>henrikn@microsoft.com</email></address>
2959    </author>
2960    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2961      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2962      <address><email>LMM@acm.org</email></address>
2963    </author>
2964    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2965      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2966      <address><email>paulle@microsoft.com</email></address>
2967    </author>
2968    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2969      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2970      <address><email>timbl@w3.org</email></address>
2971    </author>
2972    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2973      <organization abbrev="W3C">World Wide Web Consortium</organization>
2974      <address><email>ylafon@w3.org</email></address>
2975    </author>
2976    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2977      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2978      <address><email>julian.reschke@greenbytes.de</email></address>
2979    </author>
2980    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2981  </front>
2982  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
2983  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
2984</reference>
2985
2986<reference anchor="Part5">
2987  <front>
2988    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
2989    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2990      <organization abbrev="Day Software">Day Software</organization>
2991      <address><email>fielding@gbiv.com</email></address>
2992    </author>
2993    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2994      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2995      <address><email>jg@freedesktop.org</email></address>
2996    </author>
2997    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2998      <organization abbrev="HP">Hewlett-Packard Company</organization>
2999      <address><email>JeffMogul@acm.org</email></address>
3000    </author>
3001    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3002      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3003      <address><email>henrikn@microsoft.com</email></address>
3004    </author>
3005    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3006      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3007      <address><email>LMM@acm.org</email></address>
3008    </author>
3009    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3010      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3011      <address><email>paulle@microsoft.com</email></address>
3012    </author>
3013    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3014      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3015      <address><email>timbl@w3.org</email></address>
3016    </author>
3017    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3018      <organization abbrev="W3C">World Wide Web Consortium</organization>
3019      <address><email>ylafon@w3.org</email></address>
3020    </author>
3021    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3022      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3023      <address><email>julian.reschke@greenbytes.de</email></address>
3024    </author>
3025    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3026  </front>
3027  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
3028  <x:source href="p5-range.xml" basename="p5-range"/>
3029</reference>
3030
3031<reference anchor="Part6">
3032  <front>
3033    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
3034    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3035      <organization abbrev="Day Software">Day Software</organization>
3036      <address><email>fielding@gbiv.com</email></address>
3037    </author>
3038    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3039      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3040      <address><email>jg@freedesktop.org</email></address>
3041    </author>
3042    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3043      <organization abbrev="HP">Hewlett-Packard Company</organization>
3044      <address><email>JeffMogul@acm.org</email></address>
3045    </author>
3046    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3047      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3048      <address><email>henrikn@microsoft.com</email></address>
3049    </author>
3050    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3051      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3052      <address><email>LMM@acm.org</email></address>
3053    </author>
3054    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3055      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3056      <address><email>paulle@microsoft.com</email></address>
3057    </author>
3058    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3059      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3060      <address><email>timbl@w3.org</email></address>
3061    </author>
3062    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3063      <organization abbrev="W3C">World Wide Web Consortium</organization>
3064      <address><email>ylafon@w3.org</email></address>
3065    </author>
3066    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
3067      <address><email>mnot@mnot.net</email></address>
3068    </author>
3069    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3070      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3071      <address><email>julian.reschke@greenbytes.de</email></address>
3072    </author>
3073    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3074  </front>
3075  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
3076  <x:source href="p6-cache.xml" basename="p6-cache"/>
3077</reference>
3078
3079<reference anchor="Part7">
3080  <front>
3081    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
3082    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3083      <organization abbrev="Day Software">Day Software</organization>
3084      <address><email>fielding@gbiv.com</email></address>
3085    </author>
3086    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3087      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3088      <address><email>jg@freedesktop.org</email></address>
3089    </author>
3090    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3091      <organization abbrev="HP">Hewlett-Packard Company</organization>
3092      <address><email>JeffMogul@acm.org</email></address>
3093    </author>
3094    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3095      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3096      <address><email>henrikn@microsoft.com</email></address>
3097    </author>
3098    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3099      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3100      <address><email>LMM@acm.org</email></address>
3101    </author>
3102    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3103      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3104      <address><email>paulle@microsoft.com</email></address>
3105    </author>
3106    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3107      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3108      <address><email>timbl@w3.org</email></address>
3109    </author>
3110    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3111      <organization abbrev="W3C">World Wide Web Consortium</organization>
3112      <address><email>ylafon@w3.org</email></address>
3113    </author>
3114    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3115      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3116      <address><email>julian.reschke@greenbytes.de</email></address>
3117    </author>
3118    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3119  </front>
3120  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
3121  <x:source href="p7-auth.xml" basename="p7-auth"/>
3122</reference>
3123
3124<reference anchor="RFC2119">
3125  <front>
3126    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
3127    <author initials="S." surname="Bradner" fullname="Scott Bradner">
3128      <organization>Harvard University</organization>
3129      <address><email>sob@harvard.edu</email></address>
3130    </author>
3131    <date month="March" year="1997"/>
3132  </front>
3133  <seriesInfo name="BCP" value="14"/>
3134  <seriesInfo name="RFC" value="2119"/>
3135</reference>
3136
3137<reference anchor="RFC3986">
3138 <front>
3139  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
3140  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
3141    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3142    <address>
3143       <email>timbl@w3.org</email>
3144       <uri>http://www.w3.org/People/Berners-Lee/</uri>
3145    </address>
3146  </author>
3147  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
3148    <organization abbrev="Day Software">Day Software</organization>
3149    <address>
3150      <email>fielding@gbiv.com</email>
3151      <uri>http://roy.gbiv.com/</uri>
3152    </address>
3153  </author>
3154  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
3155    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
3156    <address>
3157      <email>LMM@acm.org</email>
3158      <uri>http://larry.masinter.net/</uri>
3159    </address>
3160  </author>
3161  <date month='January' year='2005'></date>
3162 </front>
3163 <seriesInfo name="STD" value="66"/>
3164 <seriesInfo name="RFC" value="3986"/>
3165</reference>
3166
3167<reference anchor="RFC5234">
3168  <front>
3169    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
3170    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3171      <organization>Brandenburg InternetWorking</organization>
3172      <address>
3173        <email>dcrocker@bbiw.net</email>
3174      </address> 
3175    </author>
3176    <author initials="P." surname="Overell" fullname="Paul Overell">
3177      <organization>THUS plc.</organization>
3178      <address>
3179        <email>paul.overell@thus.net</email>
3180      </address>
3181    </author>
3182    <date month="January" year="2008"/>
3183  </front>
3184  <seriesInfo name="STD" value="68"/>
3185  <seriesInfo name="RFC" value="5234"/>
3186</reference>
3187
3188</references>
3189
3190<references title="Informative References">
3191
3192<reference anchor="RFC1945">
3193  <front>
3194    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3195    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3196      <organization>MIT, Laboratory for Computer Science</organization>
3197      <address><email>timbl@w3.org</email></address>
3198    </author>
3199    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3200      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3201      <address><email>fielding@ics.uci.edu</email></address>
3202    </author>
3203    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3204      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3205      <address><email>frystyk@w3.org</email></address>
3206    </author>
3207    <date month="May" year="1996"/>
3208  </front>
3209  <seriesInfo name="RFC" value="1945"/>
3210</reference>
3211
3212<reference anchor="RFC2068">
3213  <front>
3214    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3215    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3216      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3217      <address><email>fielding@ics.uci.edu</email></address>
3218    </author>
3219    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3220      <organization>MIT Laboratory for Computer Science</organization>
3221      <address><email>jg@w3.org</email></address>
3222    </author>
3223    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3224      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3225      <address><email>mogul@wrl.dec.com</email></address>
3226    </author>
3227    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3228      <organization>MIT Laboratory for Computer Science</organization>
3229      <address><email>frystyk@w3.org</email></address>
3230    </author>
3231    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3232      <organization>MIT Laboratory for Computer Science</organization>
3233      <address><email>timbl@w3.org</email></address>
3234    </author>
3235    <date month="January" year="1997"/>
3236  </front>
3237  <seriesInfo name="RFC" value="2068"/>
3238</reference>
3239
3240<reference anchor="RFC2616">
3241  <front>
3242    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3243    <author initials="R." surname="Fielding" fullname="R. Fielding">
3244      <organization>University of California, Irvine</organization>
3245      <address><email>fielding@ics.uci.edu</email></address>
3246    </author>
3247    <author initials="J." surname="Gettys" fullname="J. Gettys">
3248      <organization>W3C</organization>
3249      <address><email>jg@w3.org</email></address>
3250    </author>
3251    <author initials="J." surname="Mogul" fullname="J. Mogul">
3252      <organization>Compaq Computer Corporation</organization>
3253      <address><email>mogul@wrl.dec.com</email></address>
3254    </author>
3255    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3256      <organization>MIT Laboratory for Computer Science</organization>
3257      <address><email>frystyk@w3.org</email></address>
3258    </author>
3259    <author initials="L." surname="Masinter" fullname="L. Masinter">
3260      <organization>Xerox Corporation</organization>
3261      <address><email>masinter@parc.xerox.com</email></address>
3262    </author>
3263    <author initials="P." surname="Leach" fullname="P. Leach">
3264      <organization>Microsoft Corporation</organization>
3265      <address><email>paulle@microsoft.com</email></address>
3266    </author>
3267    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3268      <organization>W3C</organization>
3269      <address><email>timbl@w3.org</email></address>
3270    </author>
3271    <date month="June" year="1999"/>
3272  </front>
3273  <seriesInfo name="RFC" value="2616"/>
3274</reference>
3275
3276<reference anchor='RFC2817'>
3277  <front>
3278    <title>Upgrading to TLS Within HTTP/1.1</title>
3279    <author initials='R.' surname='Khare' fullname='R. Khare'>
3280      <organization>4K Associates / UC Irvine</organization>
3281      <address><email>rohit@4K-associates.com</email></address>
3282    </author>
3283    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3284      <organization>Agranat Systems, Inc.</organization>
3285      <address><email>lawrence@agranat.com</email></address>
3286    </author>
3287    <date year='2000' month='May' />
3288  </front>
3289  <seriesInfo name='RFC' value='2817' />
3290</reference>
3291
3292<reference anchor='RFC3864'>
3293  <front>
3294    <title>Registration Procedures for Message Header Fields</title>
3295    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3296      <organization>Nine by Nine</organization>
3297      <address><email>GK-IETF@ninebynine.org</email></address>
3298    </author>
3299    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3300      <organization>BEA Systems</organization>
3301      <address><email>mnot@pobox.com</email></address>
3302    </author>
3303    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3304      <organization>HP Labs</organization>
3305      <address><email>JeffMogul@acm.org</email></address>
3306    </author>
3307    <date year='2004' month='September' />
3308  </front>
3309  <seriesInfo name='BCP' value='90' />
3310  <seriesInfo name='RFC' value='3864' />
3311</reference>
3312
3313<reference anchor='RFC5226'>
3314  <front>
3315    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3316    <author initials='T.' surname='Narten' fullname='T. Narten'>
3317      <organization>IBM</organization>
3318      <address><email>narten@us.ibm.com</email></address>
3319    </author>
3320    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3321      <organization>Google</organization>
3322      <address><email>Harald@Alvestrand.no</email></address>
3323    </author>
3324    <date year='2008' month='May' />
3325  </front>
3326  <seriesInfo name='BCP' value='26' />
3327  <seriesInfo name='RFC' value='5226' />
3328</reference>
3329
3330<reference anchor="RFC5322">
3331  <front>
3332    <title>Internet Message Format</title>
3333    <author initials="P." surname="Resnick" fullname="P. Resnick">
3334      <organization>Qualcomm Incorporated</organization>
3335    </author>
3336    <date year="2008" month="October"/>
3337  </front> 
3338  <seriesInfo name="RFC" value="5322"/>
3339</reference>
3340
3341</references>
3342
3343<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3344<t>
3345  This document takes over the Status Code Registry, previously defined
3346  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3347  (<xref target="status.code.registry"/>)
3348</t>
3349<t>
3350  Clarify definition of POST.
3351  (<xref target="POST"/>)
3352</t>
3353<t>
3354  Failed to consider that there are
3355  many other request methods that are safe to automatically redirect,
3356  and further that the user agent is able to make that determination
3357  based on the request method semantics.
3358  (Sections <xref format="counter" target="status.301"/>,
3359  <xref format="counter" target="status.302"/> and
3360  <xref format="counter" target="status.307"/>)
3361</t>
3362<t>
3363  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3364  It used to indicate that the target resource must be accessed through the
3365  proxy given by the Location field. The Location field gave the URI of the
3366  proxy. The recipient was expected to repeat this single request via the proxy.
3367  (<xref target="status.305"/>)
3368</t>
3369<t>
3370  Reclassify "Allow" as response header field, removing the option to
3371  specify it in a PUT request.
3372  Relax the server requirement on the contents of the Allow header field and
3373  remove requirement on clients to always trust the header field value.
3374  (<xref target="header.allow"/>)
3375</t>
3376<t>
3377  Correct syntax of Location header field to allow URI references (including
3378  relative references and fragments), as referred symbol "absoluteURI" wasn't
3379  what was expected, and add some clarifications as to when use of fragments
3380  would not be appropriate.
3381  (<xref target="header.location"/>)
3382</t>
3383<t>
3384  Allow Referer field value of "about:blank" as alternative to not specifying it.
3385  (<xref target="header.referer"/>)
3386</t>
3387<t>
3388  In the description of the Server header field, the Via field
3389  was described as a SHOULD. The requirement was and is stated
3390  correctly in the description of the Via header field in &header-via;.
3391  (<xref target="header.server"/>)
3392</t>
3393</section>
3394
3395<?BEGININC p2-semantics.abnf-appendix ?>
3396<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3397<figure>
3398<artwork type="abnf" name="p2-semantics.parsed-abnf">
3399<x:ref>Accept</x:ref> = &lt;Accept, defined in [Part3], Section 6.1&gt;
3400<x:ref>Accept-Charset</x:ref> = &lt;Accept-Charset, defined in [Part3], Section 6.2&gt;
3401<x:ref>Accept-Encoding</x:ref> = &lt;Accept-Encoding, defined in [Part3], Section 6.3&gt;
3402<x:ref>Accept-Language</x:ref> = &lt;Accept-Language, defined in [Part3], Section 6.4&gt;
3403<x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in [Part5], Section 5.1&gt;
3404<x:ref>Age</x:ref> = &lt;Age, defined in [Part6], Section 3.1&gt;
3405<x:ref>Allow</x:ref> = "Allow:" OWS Allow-v
3406<x:ref>Allow-v</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3407<x:ref>Authorization</x:ref> = &lt;Authorization, defined in [Part7], Section 4.1&gt;
3408
3409<x:ref>ETag</x:ref> = &lt;ETag, defined in [Part4], Section 6.1&gt;
3410<x:ref>Expect</x:ref> = "Expect:" OWS Expect-v
3411<x:ref>Expect-v</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3412
3413<x:ref>From</x:ref> = "From:" OWS From-v
3414<x:ref>From-v</x:ref> = mailbox
3415
3416<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3417<x:ref>Host</x:ref> = &lt;Host, defined in [Part1], Section 2.6&gt;
3418
3419<x:ref>If-Match</x:ref> = &lt;If-Match, defined in [Part4], Section 6.2&gt;
3420If-Modified-Since =
3421 &lt;If-Modified-Since, defined in [Part4], Section 6.3&gt;
3422<x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in [Part4], Section 6.4&gt;
3423<x:ref>If-Range</x:ref> = &lt;If-Range, defined in [Part5], Section 5.3&gt;
3424If-Unmodified-Since =
3425 &lt;If-Unmodified-Since, defined in [Part4], Section 6.5&gt;
3426
3427<x:ref>Location</x:ref> = "Location:" OWS Location-v
3428<x:ref>Location-v</x:ref> = URI-reference
3429
3430<x:ref>Max-Forwards</x:ref> = "Max-Forwards:" OWS Max-Forwards-v
3431<x:ref>Max-Forwards-v</x:ref> = 1*DIGIT
3432<x:ref>Method</x:ref> = %x4F.50.54.49.4F.4E.53 ; OPTIONS
3433 / %x47.45.54 ; GET
3434 / %x48.45.41.44 ; HEAD
3435 / %x50.4F.53.54 ; POST
3436 / %x50.55.54 ; PUT
3437 / %x44.45.4C.45.54.45 ; DELETE
3438 / %x54.52.41.43.45 ; TRACE
3439 / %x43.4F.4E.4E.45.43.54 ; CONNECT
3440 / extension-method
3441
3442<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3443
3444Proxy-Authenticate =
3445 &lt;Proxy-Authenticate, defined in [Part7], Section 4.2&gt;
3446Proxy-Authorization =
3447 &lt;Proxy-Authorization, defined in [Part7], Section 4.3&gt;
3448
3449<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3450<x:ref>Range</x:ref> = &lt;Range, defined in [Part5], Section 5.4&gt;
3451<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3452<x:ref>Referer</x:ref> = "Referer:" OWS Referer-v
3453<x:ref>Referer-v</x:ref> = absolute-URI / partial-URI
3454<x:ref>Retry-After</x:ref> = "Retry-After:" OWS Retry-After-v
3455<x:ref>Retry-After-v</x:ref> = HTTP-date / delta-seconds
3456
3457<x:ref>Server</x:ref> = "Server:" OWS Server-v
3458<x:ref>Server-v</x:ref> = product *( RWS ( product / comment ) )
3459<x:ref>Status-Code</x:ref> = "100" / "101" / "200" / "201" / "202" / "203" / "204" /
3460 "205" / "206" / "300" / "301" / "302" / "303" / "304" / "305" /
3461 "307" / "400" / "401" / "402" / "403" / "404" / "405" / "406" /
3462 "407" / "408" / "409" / "410" / "411" / "412" / "413" / "414" /
3463 "415" / "416" / "417" / "500" / "501" / "502" / "503" / "504" /
3464 "505" / extension-code
3465
3466<x:ref>TE</x:ref> = &lt;TE, defined in [Part1], Section 9.5&gt;
3467
3468<x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in [Part1], Section 2.6&gt;
3469<x:ref>User-Agent</x:ref> = "User-Agent:" OWS User-Agent-v
3470<x:ref>User-Agent-v</x:ref> = product *( RWS ( product / comment ) )
3471
3472<x:ref>Vary</x:ref> = &lt;Vary, defined in [Part6], Section 3.5&gt;
3473
3474WWW-Authenticate =
3475 &lt;WWW-Authenticate, defined in [Part7], Section 4.4&gt;
3476
3477<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
3478
3479<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3480
3481<x:ref>delta-seconds</x:ref> = 1*DIGIT
3482
3483<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3484<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3485<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3486 *expect-params ]
3487<x:ref>extension-code</x:ref> = 3DIGIT
3488<x:ref>extension-method</x:ref> = token
3489
3490<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3491
3492<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3493
3494<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
3495<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3496
3497<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3498
3499<x:ref>request-header</x:ref> = Accept / Accept-Charset / Accept-Encoding /
3500 Accept-Language / Authorization / Expect / From / Host / If-Match /
3501 If-Modified-Since / If-None-Match / If-Range / If-Unmodified-Since /
3502 Max-Forwards / Proxy-Authorization / Range / Referer / TE /
3503 User-Agent
3504<x:ref>response-header</x:ref> = Accept-Ranges / Age / Allow / ETag / Location /
3505 Proxy-Authenticate / Retry-After / Server / Vary / WWW-Authenticate
3506
3507<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3508</artwork>
3509</figure>
3510<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3511; Reason-Phrase defined but not used
3512; Status-Code defined but not used
3513; request-header defined but not used
3514; response-header defined but not used
3515</artwork></figure></section>
3516<?ENDINC p2-semantics.abnf-appendix ?>
3517
3518<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3519
3520<section title="Since RFC 2616">
3521<t>
3522  Extracted relevant partitions from <xref target="RFC2616"/>.
3523</t>
3524</section>
3525
3526<section title="Since draft-ietf-httpbis-p2-semantics-00">
3527<t>
3528  Closed issues:
3529  <list style="symbols"> 
3530    <t>
3531      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3532      "Via is a MUST"
3533      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3534    </t>
3535    <t>
3536      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3537      "Fragments allowed in Location"
3538      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3539    </t>
3540    <t>
3541      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3542      "Safe Methods vs Redirection"
3543      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3544    </t>
3545    <t>
3546      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3547      "Revise description of the POST method"
3548      (<eref target="http://purl.org/NET/http-errata#post"/>)
3549    </t>
3550    <t>
3551      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3552      "Normative and Informative references"
3553    </t>
3554    <t>
3555      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3556      "RFC2606 Compliance"
3557    </t>
3558    <t>
3559      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3560      "Informative references"
3561    </t>
3562    <t>
3563      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3564      "Redundant cross-references"
3565    </t>
3566  </list>
3567</t>
3568<t>
3569  Other changes:
3570  <list style="symbols"> 
3571    <t>
3572      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3573    </t>
3574  </list>
3575</t>
3576</section>
3577
3578<section title="Since draft-ietf-httpbis-p2-semantics-01">
3579<t>
3580  Closed issues:
3581  <list style="symbols"> 
3582    <t>
3583      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3584      "PUT side effects"
3585    </t>
3586    <t>
3587      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3588      "Duplicate Host header requirements"
3589    </t>
3590  </list>
3591</t>
3592<t>
3593  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3594  <list style="symbols"> 
3595    <t>
3596      Move "Product Tokens" section (back) into Part 1, as "token" is used
3597      in the definition of the Upgrade header field.
3598    </t>
3599    <t>
3600      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3601    </t>
3602    <t>
3603      Copy definition of delta-seconds from Part6 instead of referencing it.
3604    </t>
3605  </list>
3606</t>
3607</section>
3608
3609<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3610<t>
3611  Closed issues:
3612  <list style="symbols"> 
3613    <t>
3614      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3615      "Requiring Allow in 405 responses"
3616    </t>
3617    <t>
3618      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3619      "Status Code Registry"
3620    </t>
3621    <t>
3622      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3623      "Redirection vs. Location"
3624    </t>
3625    <t>
3626      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3627      "Cacheability of 303 response"
3628    </t>
3629    <t>
3630      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3631      "305 Use Proxy"
3632    </t>
3633    <t>
3634      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3635      "Classification for Allow header"
3636    </t>
3637    <t>
3638      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3639      "PUT - 'store under' vs 'store at'"
3640    </t>
3641  </list>
3642</t>
3643<t>
3644  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3645  <list style="symbols"> 
3646    <t>
3647      Reference RFC 3984, and update header field registrations for headers defined
3648      in this document.
3649    </t>
3650  </list>
3651</t>
3652<t>
3653  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3654  <list style="symbols"> 
3655    <t>
3656      Replace string literals when the string really is case-sensitive (method).
3657    </t>
3658  </list>
3659</t>
3660</section>
3661
3662<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3663<t>
3664  Closed issues:
3665  <list style="symbols"> 
3666    <t>
3667      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3668      "OPTIONS request bodies"
3669    </t>
3670    <t>
3671      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3672      "Description of CONNECT should refer to RFC2817"
3673    </t>
3674    <t>
3675      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3676      "Location Content-Location reference request/response mixup"
3677    </t>
3678  </list>
3679</t>
3680<t>
3681  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3682  <list style="symbols"> 
3683    <t>
3684      Added initial proposal for registration process, plus initial
3685      content (non-HTTP/1.1 methods to be added by a separate specification).
3686    </t>
3687  </list>
3688</t>
3689</section>
3690
3691<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3692<t>
3693  Closed issues:
3694  <list style="symbols"> 
3695    <t>
3696      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3697      "Content-*"
3698    </t>
3699    <t>
3700      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3701      "RFC 2822 is updated by RFC 5322"
3702    </t>
3703  </list>
3704</t>
3705<t>
3706  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3707  <list style="symbols"> 
3708    <t>
3709      Use "/" instead of "|" for alternatives.
3710    </t>
3711    <t>
3712      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3713      whitespace ("OWS") and required whitespace ("RWS").
3714    </t>
3715    <t>
3716      Rewrite ABNFs to spell out whitespace rules, factor out
3717      header field value format definitions.
3718    </t>
3719  </list>
3720</t>
3721</section>
3722
3723<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3724<t>
3725  Closed issues:
3726  <list style="symbols"> 
3727    <t>
3728      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3729      "Reason-Phrase BNF"
3730    </t>
3731  </list>
3732</t>
3733<t>
3734  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3735  <list style="symbols"> 
3736    <t>
3737      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3738    </t>
3739  </list>
3740</t>
3741</section>
3742
3743<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3744<t>
3745  Closed issues:
3746  <list style="symbols"> 
3747    <t>
3748      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3749      "Clarify when Referer is sent"
3750    </t>
3751    <t>
3752      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3753      "status codes vs methods"
3754    </t>
3755    <t>
3756      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3757      "Do not require "updates" relation for specs that register status codes or method names"
3758    </t>
3759  </list>
3760</t>
3761</section>
3762
3763<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3764<t>
3765  Closed issues:
3766  <list style="symbols"> 
3767    <t>
3768      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3769      "Idempotency"
3770    </t>
3771    <t>
3772      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3773      "TRACE security considerations"
3774    </t>
3775    <t>
3776      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3777      "Clarify rules for determining what entities a response carries"
3778    </t>
3779    <t>
3780      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3781      "update note citing RFC 1945 and 2068"
3782    </t>
3783    <t>
3784      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3785      "update note about redirect limit"
3786    </t>
3787    <t>
3788      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3789      "Location header ABNF should use 'URI'"
3790    </t>
3791    <t>
3792      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3793      "fragments in Location vs status 303"
3794    </t>
3795    <t>
3796      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
3797      "move IANA registrations for optional status codes"
3798    </t>
3799  </list>
3800</t>
3801<t>
3802  Partly resolved issues:
3803  <list style="symbols"> 
3804    <t>
3805      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/171"/>:
3806      "Are OPTIONS and TRACE safe?"
3807    </t>
3808  </list>
3809</t>
3810</section>
3811
3812<section title="Since draft-ietf-httpbis-p2-semantics-08" anchor="changes.since.08">
3813<t>
3814  Closed issues:
3815  <list style="symbols"> 
3816    <t>
3817      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3818      "Safe Methods vs Redirection" (we missed the introduction to the 3xx
3819      status codes when fixing this previously)
3820    </t>
3821  </list>
3822</t>
3823</section>
3824
3825<section title="Since draft-ietf-httpbis-p2-semantics-09" anchor="changes.since.09">
3826<t>
3827  Closed issues:
3828  <list style="symbols"> 
3829    <t>
3830      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
3831      "Fragment combination / precedence during redirects"
3832    </t>
3833  </list>
3834</t>
3835<t>
3836  Partly resolved issues:
3837  <list style="symbols"> 
3838    <t>
3839      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/185"/>:
3840      "Location header payload handling"
3841    </t>
3842    <t>
3843      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
3844      "Term for the requested resource's URI"
3845    </t>
3846  </list>
3847</t>
3848</section>
3849
3850<section title="Since draft-ietf-httpbis-p2-semantics-10" anchor="changes.since.10">
3851<t>
3852  Closed issues:
3853  <list style="symbols"> 
3854    <t>
3855      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
3856      "Clarify 'Requested Variant'"
3857    </t>
3858    <t>
3859      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
3860      "Clarify entity / representation / variant terminology"
3861    </t>
3862    <t>
3863      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/139"/>:
3864      "Methods and Caching"
3865    </t>
3866    <t>
3867      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/190"/>:
3868      "OPTIONS vs Max-Forwards"
3869    </t>
3870    <t>
3871      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/199"/>:
3872      "Status codes and caching"
3873    </t>
3874    <t>
3875      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
3876      "consider removing the 'changes from 2068' sections"
3877    </t>
3878  </list>
3879</t>
3880</section>
3881
3882<section title="Since draft-ietf-httpbis-p2-semantics-11" anchor="changes.since.11">
3883<t>
3884  Closed issues:
3885  <list style="symbols"> 
3886    <t>
3887      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/229"/>:
3888      "Considerations for new status codes"
3889    </t>
3890    <t>
3891      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/230"/>:
3892      "Considerations for new methods"
3893    </t>
3894    <t>
3895      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/232"/>:
3896      "User-Agent guidelines" (relating to the 'User-Agent' header field)
3897    </t>
3898  </list>
3899</t>
3900</section>
3901
3902</section>
3903
3904</back>
3905</rfc>
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