source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1034

Last change on this file since 1034 was 1034, checked in by mnot@…, 9 years ago

Explain requirements for new method registrations; addresses #230.

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