source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1035

Last change on this file since 1035 was 1035, checked in by mnot@…, 9 years ago

Explain considerations for new status codes; addresses #229.

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