source: draft-ietf-httpbis/latest/p2-semantics.xml @ 972

Last change on this file since 972 was 972, checked in by julian.reschke@…, 9 years ago

lowercase "effective request URI" throughout, use "target resource" instead of "resource identified by the effective request URI" where possible.

  • Property svn:eol-style set to native
File size: 159.9 KB
Line 
1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "August">
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 caching-combining-headers  "<xref target='Part6' x:rel='#combining.headers' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY content-negotiation        "<xref target='Part3' x:rel='#content.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY notation-abnf              "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY basic-rules                "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY uri                        "<xref target='Part1' x:rel='#uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY 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  <!ENTITY p6-combine               "<xref target='Part6' x:rel='#combining.headers'
81xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
82]>
83<?rfc toc="yes" ?>
84<?rfc symrefs="yes" ?>
85<?rfc sortrefs="yes" ?>
86<?rfc compact="yes"?>
87<?rfc subcompact="no" ?>
88<?rfc linkmailto="no" ?>
89<?rfc editing="no" ?>
90<?rfc comments="yes"?>
91<?rfc inline="yes"?>
92<?rfc rfcedstyle="yes"?>
93<?rfc-ext allow-markup-in-artwork="yes" ?>
94<?rfc-ext include-references-in-index="yes" ?>
95<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
96     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
97     xmlns:x='http://purl.org/net/xml2rfc/ext'
98     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
99<front>
100
101  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
102
103  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
104    <organization abbrev="Day Software">Day Software</organization>
105    <address>
106      <postal>
107        <street>23 Corporate Plaza DR, Suite 280</street>
108        <city>Newport Beach</city>
109        <region>CA</region>
110        <code>92660</code>
111        <country>USA</country>
112      </postal>
113      <phone>+1-949-706-5300</phone>
114      <facsimile>+1-949-706-5305</facsimile>
115      <email>fielding@gbiv.com</email>
116      <uri>http://roy.gbiv.com/</uri>
117    </address>
118  </author>
119
120  <author initials="J." surname="Gettys" fullname="Jim Gettys">
121    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
122    <address>
123      <postal>
124        <street>21 Oak Knoll Road</street>
125        <city>Carlisle</city>
126        <region>MA</region>
127        <code>01741</code>
128        <country>USA</country>
129      </postal>
130      <email>jg@freedesktop.org</email>
131      <uri>http://gettys.wordpress.com/</uri>
132    </address>
133  </author>
134 
135  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
136    <organization abbrev="HP">Hewlett-Packard Company</organization>
137    <address>
138      <postal>
139        <street>HP Labs, Large Scale Systems Group</street>
140        <street>1501 Page Mill Road, MS 1177</street>
141        <city>Palo Alto</city>
142        <region>CA</region>
143        <code>94304</code>
144        <country>USA</country>
145      </postal>
146      <email>JeffMogul@acm.org</email>
147    </address>
148  </author>
149
150  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
151    <organization abbrev="Microsoft">Microsoft Corporation</organization>
152    <address>
153      <postal>
154        <street>1 Microsoft Way</street>
155        <city>Redmond</city>
156        <region>WA</region>
157        <code>98052</code>
158        <country>USA</country>
159      </postal>
160      <email>henrikn@microsoft.com</email>
161    </address>
162  </author>
163
164  <author initials="L." surname="Masinter" fullname="Larry Masinter">
165    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
166    <address>
167      <postal>
168        <street>345 Park Ave</street>
169        <city>San Jose</city>
170        <region>CA</region>
171        <code>95110</code>
172        <country>USA</country>
173      </postal>
174      <email>LMM@acm.org</email>
175      <uri>http://larry.masinter.net/</uri>
176    </address>
177  </author>
178 
179  <author initials="P." surname="Leach" fullname="Paul J. Leach">
180    <organization abbrev="Microsoft">Microsoft Corporation</organization>
181    <address>
182      <postal>
183        <street>1 Microsoft Way</street>
184        <city>Redmond</city>
185        <region>WA</region>
186        <code>98052</code>
187      </postal>
188      <email>paulle@microsoft.com</email>
189    </address>
190  </author>
191   
192  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
193    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
194    <address>
195      <postal>
196        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
197        <street>The Stata Center, Building 32</street>
198        <street>32 Vassar Street</street>
199        <city>Cambridge</city>
200        <region>MA</region>
201        <code>02139</code>
202        <country>USA</country>
203      </postal>
204      <email>timbl@w3.org</email>
205      <uri>http://www.w3.org/People/Berners-Lee/</uri>
206    </address>
207  </author>
208
209  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
210    <organization abbrev="W3C">World Wide Web Consortium</organization>
211    <address>
212      <postal>
213        <street>W3C / ERCIM</street>
214        <street>2004, rte des Lucioles</street>
215        <city>Sophia-Antipolis</city>
216        <region>AM</region>
217        <code>06902</code>
218        <country>France</country>
219      </postal>
220      <email>ylafon@w3.org</email>
221      <uri>http://www.raubacapeu.net/people/yves/</uri>
222    </address>
223  </author>
224
225  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
226    <organization abbrev="greenbytes">greenbytes GmbH</organization>
227    <address>
228      <postal>
229        <street>Hafenweg 16</street>
230        <city>Muenster</city><region>NW</region><code>48155</code>
231        <country>Germany</country>
232      </postal>
233      <phone>+49 251 2807760</phone>
234      <facsimile>+49 251 2807761</facsimile>
235      <email>julian.reschke@greenbytes.de</email>
236      <uri>http://greenbytes.de/tech/webdav/</uri>
237    </address>
238  </author>
239
240  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
241  <workgroup>HTTPbis Working Group</workgroup>
242
243<abstract>
244<t>
245   The Hypertext Transfer Protocol (HTTP) is an application-level
246   protocol for distributed, collaborative, hypermedia information
247   systems. HTTP has been in use by the World Wide Web global information
248   initiative since 1990. This document is Part 2 of the seven-part specification
249   that defines the protocol referred to as "HTTP/1.1" and, taken together,
250   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
251   as expressed by request methods, request-header fields, response status codes,
252   and response-header fields.
253</t>
254</abstract>
255
256<note title="Editorial Note (To be removed by RFC Editor)">
257  <t>
258    Discussion of this draft should take place on the HTTPBIS working group
259    mailing list (ietf-http-wg@w3.org). The current issues list is
260    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/>
261    and related documents (including fancy diffs) can be found at
262    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
263  </t>
264  <t>
265    The changes in this draft are summarized in <xref target="changes.since.10"/>.
266  </t>
267</note>
268</front>
269<middle>
270<section title="Introduction" anchor="introduction">
271<t>
272   This document defines HTTP/1.1 request and response semantics.  Each HTTP
273   message, as defined in &messaging;, is in the form of either a request or
274   a response.  An HTTP server listens on a connection for HTTP requests and
275   responds to each request, in the order received on that connection, with
276   one or more HTTP response messages.  This document defines the commonly
277   agreed upon semantics of the HTTP uniform interface, the intentions defined
278   by each request method, and the various response messages that might be
279   expected as a result of applying that method to the target resource.
280</t>
281<t>
282   This document is currently disorganized in order to minimize the changes
283   between drafts and enable reviewers to see the smaller errata changes.
284   The next draft will reorganize the sections to better reflect the content.
285   In particular, the sections will be ordered according to the typical
286   processing of an HTTP request message (after message parsing): resource
287   mapping, general header fields, methods, request modifiers, response
288   status, and resource metadata.  The current mess reflects how widely
289   dispersed these topics and associated requirements had become in
290   <xref target="RFC2616"/>.
291</t>
292
293<section title="Requirements" anchor="intro.requirements">
294<t>
295   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
296   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
297   document are to be interpreted as described in <xref target="RFC2119"/>.
298</t>
299<t>
300   An implementation is not compliant if it fails to satisfy one or more
301   of the "MUST" or "REQUIRED" level requirements for the protocols it
302   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
303   level and all the "SHOULD" level requirements for its protocols is said
304   to be "unconditionally compliant"; one that satisfies all the "MUST"
305   level requirements but not all the "SHOULD" level requirements for its
306   protocols is said to be "conditionally compliant".
307</t>
308</section>
309
310<section title="Syntax Notation" anchor="notation">
311  <x:anchor-alias value="CR"/>
312  <x:anchor-alias value="DIGIT"/>
313  <x:anchor-alias value="LF"/>
314  <x:anchor-alias value="VCHAR"/>
315  <x:anchor-alias value="WSP"/>
316<t>
317  This specification uses the ABNF syntax defined in &notation; (which
318  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
319  <xref target="collected.abnf"/> shows the collected ABNF, with the list
320  rule expanded.
321</t>
322<t>
323  The following core rules are included by
324  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
325  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
326  DIGIT (decimal 0-9), DQUOTE (double quote),
327  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
328  OCTET (any 8-bit sequence of data), SP (space),
329  VCHAR (any visible USASCII character),
330  and WSP (whitespace).
331</t>
332
333<section title="Core Rules" anchor="core.rules">
334  <x:anchor-alias value="obs-text"/>
335  <x:anchor-alias value="quoted-string"/>
336  <x:anchor-alias value="token"/>
337  <x:anchor-alias value="OWS"/>
338  <x:anchor-alias value="RWS"/>
339<t>
340  The core rules below are defined in &basic-rules;:
341</t>
342<figure><artwork type="abnf2616">
343  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
344  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
345  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
346  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
347  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
348</artwork></figure>
349</section>
350
351<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
352  <x:anchor-alias value="absolute-URI"/>
353  <x:anchor-alias value="Accept"/>
354  <x:anchor-alias value="Accept-Charset"/>
355  <x:anchor-alias value="Accept-Encoding"/>
356  <x:anchor-alias value="Accept-Language"/>
357  <x:anchor-alias value="Accept-Ranges"/>
358  <x:anchor-alias value="Age"/>
359  <x:anchor-alias value="Authorization"/>
360  <x:anchor-alias value="comment"/>
361  <x:anchor-alias value="ETag"/>
362  <x:anchor-alias value="Host"/>
363  <x:anchor-alias value="HTTP-date"/>
364  <x:anchor-alias value="If-Match"/>
365  <x:anchor-alias value="If-Modified-Since"/>
366  <x:anchor-alias value="If-None-Match"/>
367  <x:anchor-alias value="If-Range"/>
368  <x:anchor-alias value="If-Unmodified-Since"/>
369  <x:anchor-alias value="partial-URI"/>
370  <x:anchor-alias value="product"/>
371  <x:anchor-alias value="Proxy-Authenticate"/>
372  <x:anchor-alias value="Proxy-Authorization"/>
373  <x:anchor-alias value="Range"/>
374  <x:anchor-alias value="TE"/>
375  <x:anchor-alias value="URI-reference"/>
376  <x:anchor-alias value="Vary"/>
377  <x:anchor-alias value="WWW-Authenticate"/>
378<t>
379  The ABNF rules below are defined in other parts:
380</t>
381<figure><!--Part1--><artwork type="abnf2616">
382  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
383  <x:ref>comment</x:ref>       = &lt;comment, defined in &header-fields;&gt;
384  <x:ref>Host</x:ref>          = &lt;Host, defined in &uri;&gt;
385  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
386  <x:ref>partial-URI</x:ref>   = &lt;partial-URI, defined in &uri;&gt;
387  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
388  <x:ref>TE</x:ref>            = &lt;TE, defined in &header-te;&gt;
389  <x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in &uri;&gt;
390</artwork></figure>
391<figure><!--Part3--><artwork type="abnf2616">
392  <x:ref>Accept</x:ref>        = &lt;Accept, defined in &header-accept;&gt;
393  <x:ref>Accept-Charset</x:ref> =
394             &lt;Accept-Charset, defined in &header-accept-charset;&gt;
395  <x:ref>Accept-Encoding</x:ref> =
396             &lt;Accept-Encoding, defined in &header-accept-encoding;&gt;
397  <x:ref>Accept-Language</x:ref> =
398             &lt;Accept-Language, defined in &header-accept-language;&gt;
399</artwork></figure>
400<figure><!--Part4--><artwork type="abnf2616">
401  <x:ref>ETag</x:ref>          = &lt;ETag, defined in &header-etag;&gt;
402  <x:ref>If-Match</x:ref>      = &lt;If-Match, defined in &header-if-match;&gt;
403  <x:ref>If-Modified-Since</x:ref> =
404             &lt;If-Modified-Since, defined in &header-if-modified-since;&gt;
405  <x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in &header-if-none-match;&gt;
406  <x:ref>If-Unmodified-Since</x:ref> =
407             &lt;If-Unmodified-Since, defined in &header-if-unmodified-since;&gt;
408</artwork></figure>
409<figure><!--Part5--><artwork type="abnf2616">
410  <x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in &header-accept-ranges;&gt;
411  <x:ref>If-Range</x:ref>      = &lt;If-Range, defined in &header-if-range;&gt;
412  <x:ref>Range</x:ref>         = &lt;Range, defined in &header-range;&gt;
413</artwork></figure>
414<figure><!--Part6--><artwork type="abnf2616">
415  <x:ref>Age</x:ref>           = &lt;Age, defined in &header-age;&gt;
416  <x:ref>Vary</x:ref>          = &lt;Vary, defined in &header-vary;&gt;
417</artwork><!--Part7--></figure>
418<figure><artwork type="abnf2616">
419  <x:ref>Authorization</x:ref> = &lt;Authorization, defined in &header-authorization;&gt;
420  <x:ref>Proxy-Authenticate</x:ref> =
421             &lt;Proxy-Authenticate, defined in &header-proxy-authenticate;&gt;
422  <x:ref>Proxy-Authorization</x:ref> =
423             &lt;Proxy-Authorization, defined in &header-proxy-authorization;&gt;
424  <x:ref>WWW-Authenticate</x:ref> =
425             &lt;WWW-Authenticate, defined in &header-www-authenticate;&gt;
426</artwork></figure>
427</section>
428</section>
429</section>
430
431<section title="Method" anchor="method">
432  <x:anchor-alias value="Method"/>
433  <x:anchor-alias value="extension-method"/>
434<t>
435   The Method token indicates the method to be performed on the target
436   resource (&effective-request-uri;). The method is case-sensitive.
437</t>
438<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/><iref primary="true" item="Grammar" subitem="extension-method"/>
439  <x:ref>Method</x:ref>         = <x:abnf-char-sequence>"OPTIONS"</x:abnf-char-sequence>   ; "OPTIONS", <xref target="OPTIONS"/>
440                 / <x:abnf-char-sequence>"GET"</x:abnf-char-sequence>               ; "GET", <xref target="GET"/>
441                 / <x:abnf-char-sequence>"HEAD"</x:abnf-char-sequence>            ; "HEAD", <xref target="HEAD"/>
442                 / <x:abnf-char-sequence>"POST"</x:abnf-char-sequence>            ; "POST", <xref target="POST"/>
443                 / <x:abnf-char-sequence>"PUT"</x:abnf-char-sequence>               ; "PUT", <xref target="PUT"/>
444                 / <x:abnf-char-sequence>"DELETE"</x:abnf-char-sequence>      ; "DELETE", <xref target="DELETE"/>
445                 / <x:abnf-char-sequence>"TRACE"</x:abnf-char-sequence>         ; "TRACE", <xref target="TRACE"/>
446                 / <x:abnf-char-sequence>"CONNECT"</x:abnf-char-sequence>   ; "CONNECT", <xref target="CONNECT"/>
447                 / <x:ref>extension-method</x:ref>
448  <x:ref>extension-method</x:ref> = <x:ref>token</x:ref>
449</artwork></figure>
450<t>
451   The list of methods allowed by a resource can be specified in an
452   Allow header field (<xref target="header.allow"/>). The status code of the response
453   always notifies the client whether a method is currently allowed on a
454   resource, since the set of allowed methods can change dynamically. An
455   origin server &SHOULD; respond with the status code 405 (Method Not Allowed)
456   if the method is known by the origin server but not allowed for the
457   resource, and 501 (Not Implemented) if the method is
458   unrecognized or not implemented by the origin server. The methods GET
459   and HEAD &MUST; be supported by all general-purpose servers. All other
460   methods are &OPTIONAL;; however, if the above methods are implemented,
461   they &MUST; be implemented with the same semantics as those specified
462   in <xref target="method.definitions"/>.
463</t>
464
465<section title="Method Registry" anchor="method.registry">
466<t>
467  The HTTP Method Registry defines the name space for the Method token in the
468  Request line of an HTTP request.
469</t>
470<t>
471  Registrations &MUST; include the following fields:
472  <list style="symbols">
473    <t>Method Name (see <xref target="method"/>)</t>
474    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
475    <t>Pointer to specification text</t>
476  </list>
477</t>
478<t>
479  Values to be added to this name space are subject to IETF review
480  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
481</t>
482<t>
483  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
484</t>
485</section>
486</section>
487
488<section title="Request Header Fields" anchor="request.header.fields">
489  <x:anchor-alias value="request-header"/>
490<t>
491   The request-header fields allow the client to pass additional
492   information about the request, and about the client itself, to the
493   server. These fields act as request modifiers, with semantics
494   equivalent to the parameters on a programming language method
495   invocation.
496</t>
497<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="request-header"/>
498  <x:ref>request-header</x:ref> = <x:ref>Accept</x:ref>                   ; &header-accept;
499                 / <x:ref>Accept-Charset</x:ref>           ; &header-accept-charset;
500                 / <x:ref>Accept-Encoding</x:ref>          ; &header-accept-encoding;
501                 / <x:ref>Accept-Language</x:ref>          ; &header-accept-language;
502                 / <x:ref>Authorization</x:ref>            ; &header-authorization;
503                 / <x:ref>Expect</x:ref>                   ; <xref target="header.expect"/>
504                 / <x:ref>From</x:ref>                     ; <xref target="header.from"/>
505                 / <x:ref>Host</x:ref>                     ; &header-host;
506                 / <x:ref>If-Match</x:ref>                 ; &header-if-match;
507                 / <x:ref>If-Modified-Since</x:ref>        ; &header-if-modified-since;
508                 / <x:ref>If-None-Match</x:ref>            ; &header-if-none-match;
509                 / <x:ref>If-Range</x:ref>                 ; &header-if-range;
510                 / <x:ref>If-Unmodified-Since</x:ref>      ; &header-if-unmodified-since;
511                 / <x:ref>Max-Forwards</x:ref>             ; <xref target="header.max-forwards"/>
512                 / <x:ref>Proxy-Authorization</x:ref>      ; &header-proxy-authorization;
513                 / <x:ref>Range</x:ref>                    ; &header-range;
514                 / <x:ref>Referer</x:ref>                  ; <xref target="header.referer"/>
515                 / <x:ref>TE</x:ref>                       ; &header-te;
516                 / <x:ref>User-Agent</x:ref>               ; <xref target="header.user-agent"/>
517</artwork></figure>
518<t>
519   Request-header field names can be extended reliably only in
520   combination with a change in the protocol version. However, new or
521   experimental header fields &MAY; be given the semantics of request-header
522   fields if all parties in the communication recognize them to
523   be request-header fields.
524</t>
525</section>
526
527<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
528  <x:anchor-alias value="Reason-Phrase"/>
529  <x:anchor-alias value="Status-Code"/>
530  <x:anchor-alias value="extension-code"/>
531<t>
532   The Status-Code element is a 3-digit integer result code of the
533   attempt to understand and satisfy the request. The status codes listed
534   below are defined in <xref target="status.codes"/>, &p4-status-codes;,
535   &p5-status-codes;, and &p7-status-codes;.
536</t>
537<t>
538   The Reason-Phrase is intended to give a short
539   textual description of the Status-Code. The Status-Code is intended
540   for use by automata and the Reason-Phrase is intended for the human
541   user. The client is not required to examine or display the Reason-Phrase.
542</t>
543<t> 
544   The individual values of the numeric status codes defined for
545   HTTP/1.1, and an example set of corresponding Reason-Phrase values, are
546   presented below. The reason phrases listed here are only
547   recommendations -- they &MAY; be replaced by local equivalents without
548   affecting the protocol.
549</t>
550<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"/>
551  <x:ref>Status-Code</x:ref> =
552       "100"  ; <xref target="status.100"/>: Continue
553     / "101"  ; <xref target="status.101"/>: Switching Protocols
554     / "200"  ; <xref target="status.200"/>: OK
555     / "201"  ; <xref target="status.201"/>: Created
556     / "202"  ; <xref target="status.202"/>: Accepted
557     / "203"  ; <xref target="status.203"/>: Non-Authoritative Information
558     / "204"  ; <xref target="status.204"/>: No Content
559     / "205"  ; <xref target="status.205"/>: Reset Content
560     / "206"  ; &status-206;: Partial Content
561     / "300"  ; <xref target="status.300"/>: Multiple Choices
562     / "301"  ; <xref target="status.301"/>: Moved Permanently
563     / "302"  ; <xref target="status.302"/>: Found
564     / "303"  ; <xref target="status.303"/>: See Other
565     / "304"  ; &status-304;: Not Modified
566     / "305"  ; <xref target="status.305"/>: Use Proxy
567     / "307"  ; <xref target="status.307"/>: Temporary Redirect
568     / "400"  ; <xref target="status.400"/>: Bad Request
569     / "401"  ; &status-401;: Unauthorized
570     / "402"  ; <xref target="status.402"/>: Payment Required
571     / "403"  ; <xref target="status.403"/>: Forbidden
572     / "404"  ; <xref target="status.404"/>: Not Found
573     / "405"  ; <xref target="status.405"/>: Method Not Allowed
574     / "406"  ; <xref target="status.406"/>: Not Acceptable
575     / "407"  ; &status-407;: Proxy Authentication Required
576     / "408"  ; <xref target="status.408"/>: Request Time-out
577     / "409"  ; <xref target="status.409"/>: Conflict
578     / "410"  ; <xref target="status.410"/>: Gone
579     / "411"  ; <xref target="status.411"/>: Length Required
580     / "412"  ; &status-412;: Precondition Failed
581     / "413"  ; <xref target="status.413"/>: Request Entity Too Large
582     / "414"  ; <xref target="status.414"/>: URI Too Long
583     / "415"  ; <xref target="status.415"/>: Unsupported Media Type
584     / "416"  ; &status-416;: Requested range not satisfiable
585     / "417"  ; <xref target="status.417"/>: Expectation Failed
586     / "500"  ; <xref target="status.500"/>: Internal Server Error
587     / "501"  ; <xref target="status.501"/>: Not Implemented
588     / "502"  ; <xref target="status.502"/>: Bad Gateway
589     / "503"  ; <xref target="status.503"/>: Service Unavailable
590     / "504"  ; <xref target="status.504"/>: Gateway Time-out
591     / "505"  ; <xref target="status.505"/>: HTTP Version not supported
592     / <x:ref>extension-code</x:ref>
593
594  <x:ref>extension-code</x:ref> = 3<x:ref>DIGIT</x:ref>
595  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
596</artwork></figure>
597<t>
598   HTTP status codes are extensible. HTTP applications are not required
599   to understand the meaning of all registered status codes, though such
600   understanding is obviously desirable. However, applications &MUST;
601   understand the class of any status code, as indicated by the first
602   digit, and treat any unrecognized response as being equivalent to the
603   x00 status code of that class, with the exception that an
604   unrecognized response &MUST-NOT; be cached. For example, if an
605   unrecognized status code of 431 is received by the client, it can
606   safely assume that there was something wrong with its request and
607   treat the response as if it had received a 400 status code. In such
608   cases, user agents &SHOULD; present to the user the representation enclosed
609   with the response, since that representation is likely to include human-readable
610   information which will explain the unusual status.
611</t>
612
613<section title="Status Code Registry" anchor="status.code.registry">
614<t>
615  The HTTP Status Code Registry defines the name space for the Status-Code
616  token in the Status-Line of an HTTP response.
617</t>
618<t>
619  Values to be added to this name space are subject to IETF review
620  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
621</t>
622<t>
623  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
624</t>
625</section>
626
627</section>
628
629<section title="Response Header Fields" anchor="response.header.fields">
630  <x:anchor-alias value="response-header"/>
631<t>
632   The response-header fields allow the server to pass additional
633   information about the response which cannot be placed in the Status-Line.
634   These header fields give information about the server and about
635   further access to the target resource (&effective-request-uri;).
636</t>
637<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="response-header"/>
638  <x:ref>response-header</x:ref> = <x:ref>Accept-Ranges</x:ref>           ; &header-accept-ranges;
639                  / <x:ref>Age</x:ref>                     ; &header-age;
640                  / <x:ref>Allow</x:ref>                   ; <xref target="header.allow"/>
641                  / <x:ref>ETag</x:ref>                    ; &header-etag;
642                  / <x:ref>Location</x:ref>                ; <xref target="header.location"/>
643                  / <x:ref>Proxy-Authenticate</x:ref>      ; &header-proxy-authenticate;
644                  / <x:ref>Retry-After</x:ref>             ; <xref target="header.retry-after"/>
645                  / <x:ref>Server</x:ref>                  ; <xref target="header.server"/>
646                  / <x:ref>Vary</x:ref>                    ; &header-vary;
647                  / <x:ref>WWW-Authenticate</x:ref>        ; &header-www-authenticate;
648</artwork></figure>
649<t>
650   Response-header field names can be extended reliably only in
651   combination with a change in the protocol version. However, new or
652   experimental header fields &MAY; be given the semantics of response-header
653   fields if all parties in the communication recognize them to
654   be response-header fields.
655</t>
656</section>
657
658<section title="Representation" anchor="representation">
659<t>
660   Request and Response messages &MAY; transfer a representation if not otherwise
661   restricted by the request method or response status code. A representation
662   consists of metadata (representation header fields) and data (representation
663   body).  When a complete or partial representation is enclosed in an HTTP message,
664   it is referred to as the payload of the message. HTTP representations
665   are defined in &payload;.
666</t>
667<t>
668   A representation body is only present in a message when a message-body is
669   present, as described in &message-body;. The representation body is obtained
670   from the message-body by decoding any Transfer-Encoding that might
671   have been applied to ensure safe and proper transfer of the message.
672</t>
673
674<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
675<t>
676   It is sometimes necessary to determine an identifier for the resource
677   associated with a representation.
678</t>
679<t>
680   An HTTP request representation, when present, is always associated with an
681   anonymous (i.e., unidentified) resource.
682</t>
683<t>
684   In the common case, an HTTP response is a representation of the target
685   resource (see &effective-request-uri;). However, this is not always the
686   case. To determine the URI of the resource a response is associated with,
687   the following rules are used (with the first applicable one being selected):
688</t>
689<t><list style="numbers">
690   <t>If the response status code is 200 or 203 and the request method was GET,
691   the response payload is a representation of the target resource.</t>
692   <t>If the response status code is 204, 206, or 304 and the request method was GET
693   or HEAD, the response payload is a partial representation of the target
694   (see &caching-combining-headers;).</t>
695   <t>If the response has a Content-Location header, and that URI is the same
696   as the effective request URI, the response payload is a representation of the
697   target resource.</t>
698   <t>If the response has a Content-Location header, and that URI is not the
699   same as the effective request URI, then the response asserts that its
700   payload is a representation of the resource identified by the
701   Content-Location URI. However, such an assertion cannot be trusted unless
702   it can be verified by other means (not defined by HTTP).</t>
703   <t>Otherwise, the response is a representation of an anonymous (i.e.,
704   unidentified) resource.</t>
705</list></t>
706<t>
707  <cref anchor="TODO-req-uri">
708   The comparison function is going to have to be defined somewhere,
709   because we already need to compare URIs for things like cache invalidation.</cref>
710</t>
711</section>
712
713</section>
714
715
716<section title="Method Definitions" anchor="method.definitions">
717<t>
718   The set of common methods for HTTP/1.1 is defined below. Although
719   this set can be expanded, additional methods cannot be assumed to
720   share the same semantics for separately extended clients and servers.
721</t>
722
723<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
724
725<section title="Safe Methods" anchor="safe.methods">
726<iref item="Safe Methods" primary="true"/>
727<t>
728   Implementors need to be aware that the software represents the user in
729   their interactions over the Internet, and need to allow
730   the user to be aware of any actions they take which might have an
731   unexpected significance to themselves or others.
732</t>
733<t>
734   In particular, the convention has been established that the GET, HEAD,
735   OPTIONS, and TRACE methods &SHOULD-NOT; have the significance of taking an action
736   other than retrieval. These methods ought to be considered "<x:dfn anchor="safe">safe</x:dfn>".
737   This allows user agents to represent other methods, such as POST, PUT
738   and DELETE, in a special way, so that the user is made aware of the
739   fact that a possibly unsafe action is being requested.
740</t>
741<t>
742   Naturally, it is not possible to ensure that the server does not
743   generate side-effects as a result of performing a GET request; in
744   fact, some dynamic resources consider that a feature. The important
745   distinction here is that the user did not request the side-effects,
746   so therefore cannot be held accountable for them.
747</t>
748</section>
749
750<section title="Idempotent Methods" anchor="idempotent.methods">
751<iref item="Idempotent Methods" primary="true"/>
752<t>
753   Methods can also have the property of "idempotence" in that, aside
754   from error or expiration issues, the intended effect of multiple
755   identical requests is the same as for a single request.
756   The methods PUT, DELETE, and all safe methods are idempotent.
757   It is important to note that idempotence refers only to changes
758   requested by the client: a server is free to change its state due
759   to multiple requests for the purpose of tracking those requests,
760   versioning of results, etc.
761</t>
762</section>
763</section>
764
765<section title="OPTIONS" anchor="OPTIONS">
766  <rdf:Description>
767    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
768  </rdf:Description>
769  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
770  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
771<t>
772   The OPTIONS method represents a request for information about the
773   communication options available on the request/response chain
774   identified by the effective request URI. This method allows the client to
775   determine the options and/or requirements associated with a resource,
776   or the capabilities of a server, without implying a resource action
777   or initiating a resource retrieval.
778</t>
779<t>
780   Responses to this method are not cacheable.
781</t>
782<t>
783   If the OPTIONS request includes a message-body (as indicated by the
784   presence of Content-Length or Transfer-Encoding), then the media type
785   &MUST; be indicated by a Content-Type field. Although this
786   specification does not define any use for such a body, future
787   extensions to HTTP might use the OPTIONS body to make more detailed
788   queries on the server.
789</t>
790<t>
791   If the request-target is an asterisk ("*"), the OPTIONS request is
792   intended to apply to the server in general rather than to a specific
793   resource. Since a server's communication options typically depend on
794   the resource, the "*" request is only useful as a "ping" or "no-op"
795   type of method; it does nothing beyond allowing the client to test
796   the capabilities of the server. For example, this can be used to test
797   a proxy for HTTP/1.1 compliance (or lack thereof).
798</t>
799<t>
800   If the request-target is not an asterisk, the OPTIONS request applies
801   only to the options that are available when communicating with that
802   resource.
803</t>
804<t>
805   A 200 response &SHOULD; include any header fields that indicate
806   optional features implemented by the server and applicable to that
807   resource (e.g., Allow), possibly including extensions not defined by
808   this specification. The response body, if any, &SHOULD; also include
809   information about the communication options. The format for such a
810   body is not defined by this specification, but might be defined by
811   future extensions to HTTP. Content negotiation &MAY; be used to select
812   the appropriate response format. If no response body is included, the
813   response &MUST; include a Content-Length field with a field-value of
814   "0".
815</t>
816<t>
817   The Max-Forwards request-header field &MAY; be used to target a
818   specific proxy in the request chain (see <xref target="header.max-forwards"/>).
819   If no Max-Forwards field is present in the request, then the forwarded
820   request &MUST-NOT; include a Max-Forwards field.
821</t>
822</section>
823
824<section title="GET" anchor="GET">
825  <rdf:Description>
826    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
827  </rdf:Description>
828  <iref primary="true" item="GET method" x:for-anchor=""/>
829  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
830<t>
831   The GET method means retrieve whatever information (in the form of a
832   representation) currently corresponds to the target resource.
833</t>
834<t>   
835   If the target resource is a data-producing process, it is the
836   produced data which shall be returned as the representation in the response and not
837   the source text of the process, unless that text happens to be the output of
838   the process.
839</t>
840<t>
841   The semantics of the GET method change to a "conditional GET" if the
842   request message includes an If-Modified-Since, If-Unmodified-Since,
843   If-Match, If-None-Match, or If-Range header field. A conditional GET
844   method requests that the representation be transferred only under the
845   circumstances described by the conditional header field(s). The
846   conditional GET method is intended to reduce unnecessary network
847   usage by allowing cached representations to be refreshed without requiring
848   multiple requests or transferring data already held by the client.
849</t>
850<t>
851   The semantics of the GET method change to a "partial GET" if the
852   request message includes a Range header field. A partial GET requests
853   that only part of the representation be transferred, as described in &header-range;.
854   The partial GET method is intended to reduce unnecessary
855   network usage by allowing partially-retrieved representations to be
856   completed without transferring data already held by the client.
857</t>
858<t>
859   The response to a GET request is cacheable and &MAY; be used to satisfy
860   subsequent GET and HEAD requests (see &caching;).
861</t>
862<t>
863   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
864</t>
865</section>
866
867<section title="HEAD" anchor="HEAD">
868  <rdf:Description>
869    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
870  </rdf:Description>
871  <iref primary="true" item="HEAD method" x:for-anchor=""/>
872  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
873<t>
874   The HEAD method is identical to GET except that the server &MUST-NOT;
875   return a message-body in the response. The metadata contained
876   in the HTTP headers in response to a HEAD request &SHOULD; be identical
877   to the information sent in response to a GET request. This method can
878   be used for obtaining metadata about the representation implied by the
879   request without transferring the representation body. This method is
880   often used for testing hypertext links for validity, accessibility,
881   and recent modification.
882</t>
883<t>
884   The response to a HEAD request is cacheable and &MAY; be used to satisfy
885   a subsequent HEAD request; see &caching;. It also &MAY; be used to update a previously cached
886   representation from that resource; if the new field values
887   indicate that the cached representation differs from the current representation (as
888   would be indicated by a change in Content-Length, Content-MD5, ETag
889   or Last-Modified), then the cache &MUST; treat the cache entry as
890   stale.
891</t>
892</section>
893
894<section title="POST" anchor="POST">
895  <iref primary="true" item="POST method" x:for-anchor=""/>
896  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
897<t>
898   The POST method is used to request that the origin server accept the
899   representation enclosed in the request as data to be processed by the
900   target resource. POST is designed to allow a uniform method to cover the
901   following functions:
902  <list style="symbols">
903    <t>
904      Annotation of existing resources;
905    </t>
906    <t>
907        Posting a message to a bulletin board, newsgroup, mailing list,
908        or similar group of articles;
909    </t>
910    <t>
911        Providing a block of data, such as the result of submitting a
912        form, to a data-handling process;
913    </t>
914    <t>
915        Extending a database through an append operation.
916    </t>
917  </list>
918</t>
919<t>
920   The actual function performed by the POST method is determined by the
921   server and is usually dependent on the effective request URI.
922</t>
923<t>
924   The action performed by the POST method might not result in a
925   resource that can be identified by a URI. In this case, either 200
926   (OK) or 204 (No Content) is the appropriate response status code,
927   depending on whether or not the response includes a representation that
928   describes the result.
929</t>
930<t>
931   If a resource has been created on the origin server, the response
932   &SHOULD; be 201 (Created) and contain a representation which describes the
933   status of the request and refers to the new resource, and a Location
934   header (see <xref target="header.location"/>).
935</t>
936<t>
937   Responses to POST requests are only cacheable when they
938   include explicit freshness information (see &p6-explicit;). A
939   cached POST response with a Content-Location header
940   (see &header-content-location;) whose value is the effective
941   Request URI &MAY; be used to satisfy subsequent GET and HEAD requests.
942</t>
943<t>
944   Note that POST caching is not widely implemented.
945   However, the 303 (See Other) response can be used to direct the
946   user agent to retrieve a cacheable resource.
947</t>
948</section>
949
950<section title="PUT" anchor="PUT">
951  <iref primary="true" item="PUT method" x:for-anchor=""/>
952  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
953<t>
954   The PUT method requests that the enclosed representation be stored at the
955   effective request URI. If the effective request URI refers to an already
956   existing resource, the enclosed representation &SHOULD; be considered a
957   modified version of the one residing on the origin server. Otherwise, if the
958   effective request URI does not point to an existing resource, and that URI is
959   capable of being defined as a new resource by the requesting user
960   agent, the origin server can create the resource with that URI.
961</t>
962<t>   
963   If a new resource is created at the effective request URI, the origin
964   server &MUST; inform the user agent
965   via the 201 (Created) response. If an existing resource is modified,
966   either the 200 (OK) or 204 (No Content) response codes &SHOULD; be sent
967   to indicate successful completion of the request.
968</t>
969<t>   
970   If the target resource could not be created or modified, an appropriate
971   error response &SHOULD; be given that reflects the nature of the problem.
972   The recipient of the representation &MUST-NOT; ignore any Content-*
973   headers (headers starting with the prefix "Content-") that it does
974   not understand or implement
975   and &MUST; return a 501 (Not Implemented) response in such cases.
976</t>
977<t>
978   If the request passes through a cache that has one or more stored
979   responses for the effective request URI, those stored responses
980   &SHOULD; be marked as stale if the response to the PUT request
981   has a success status code. Responses to the PUT method are
982   not cacheable.
983</t>
984<t>
985   The fundamental difference between the POST and PUT requests is
986   reflected in the different meaning of the effective request URI. The URI in a
987   POST request identifies the resource that will handle the enclosed
988   representation. That resource might be a data-accepting process, a gateway to
989   some other protocol, or a document that accepts annotations.
990   In contrast, the URI in a PUT request identifies the resource for
991   which enclosed representation is a new or replacement value; the
992   user agent knows what URI is intended and the server &MUST-NOT; attempt
993   to apply the request to some other resource.
994   If the server desires that the request be applied to a different URI,
995   it &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
996   then make its own decision regarding whether or not to redirect the
997   request.
998</t>
999<t>
1000   A single resource &MAY; be identified by many different URIs. For
1001   example, an article might have a URI for identifying "the current
1002   version" which is separate from the URI identifying each particular
1003   version. In this case, a PUT request on a general URI might result in
1004   several other URIs being defined by the origin server.
1005</t>
1006<t>
1007   HTTP/1.1 does not define how a PUT method affects the state of an
1008   origin server.
1009</t>
1010<t>
1011   Header fields in a PUT request that are recognized as representation
1012   metadata &SHOULD; be applied to the resource created or modified by
1013   the PUT.  Unrecognized header fields &SHOULD; be ignored.
1014</t>
1015</section>
1016
1017<section title="DELETE" anchor="DELETE">
1018  <iref primary="true" item="DELETE method" x:for-anchor=""/>
1019  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
1020<t>
1021   The DELETE method requests that the origin server delete the target
1022   resource. This method &MAY; be overridden by
1023   human intervention (or other means) on the origin server. The client cannot
1024   be guaranteed that the operation has been carried out, even if the
1025   status code returned from the origin server indicates that the action
1026   has been completed successfully. However, the server &SHOULD-NOT; 
1027   indicate success unless, at the time the response is given, it
1028   intends to delete the resource or move it to an inaccessible
1029   location.
1030</t>
1031<t>
1032   A successful response &SHOULD; be 200 (OK) if the response includes an
1033   representation describing the status, 202 (Accepted) if the action has not
1034   yet been enacted, or 204 (No Content) if the action has been enacted
1035   but the response does not include a representation.
1036</t>
1037<t>
1038   If the request passes through a cache and the effective request URI
1039   identifies one or more currently cached representations, those entries &SHOULD; be
1040   treated as stale. Responses to the DELETE method are not cacheable.
1041</t>
1042</section>
1043
1044<section title="TRACE" anchor="TRACE">
1045  <rdf:Description>
1046    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1047  </rdf:Description>
1048  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1049  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1050<t>
1051   The TRACE method is used to invoke a remote, application-layer loop-back
1052   of the request message. The final recipient of the request
1053   &SHOULD; reflect the message received back to the client as the
1054   message-body of a 200 (OK) response. The final recipient is either the
1055   origin server or the first proxy or gateway to receive a Max-Forwards
1056   value of zero (0) in the request (see <xref target="header.max-forwards"/>).
1057   A TRACE request &MUST-NOT; include a message-body.
1058</t>
1059<t>
1060   TRACE allows the client to see what is being received at the other
1061   end of the request chain and use that data for testing or diagnostic
1062   information. The value of the Via header field (&header-via;) is of
1063   particular interest, since it acts as a trace of the request chain.
1064   Use of the Max-Forwards header field allows the client to limit the
1065   length of the request chain, which is useful for testing a chain of
1066   proxies forwarding messages in an infinite loop.
1067</t>
1068<t>
1069   If the request is valid, the response &SHOULD; have a Content-Type of
1070   "message/http" (see &media-type-message-http;) and contain a message-body
1071   that encloses a copy of the entire request message.
1072   Responses to the TRACE method are not cacheable.
1073</t>
1074</section>
1075
1076<section title="CONNECT" anchor="CONNECT">
1077  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1078  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1079<t>
1080   This specification reserves the method name CONNECT for use with a
1081   proxy that can dynamically switch to being a tunnel (e.g., SSL
1082   tunneling <xref target="RFC2817"/>).
1083</t>
1084</section>
1085</section>
1086
1087
1088<section title="Status Code Definitions" anchor="status.codes">
1089<t>
1090   Each Status-Code is described below, including any metadata required
1091   in the response.
1092</t>
1093
1094<section title="Informational 1xx" anchor="status.1xx">
1095<t>
1096   This class of status code indicates a provisional response,
1097   consisting only of the Status-Line and optional headers, and is
1098   terminated by an empty line. There are no required headers for this
1099   class of status code. Since HTTP/1.0 did not define any 1xx status
1100   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1101   except under experimental conditions.
1102</t>
1103<t>
1104   A client &MUST; be prepared to accept one or more 1xx status responses
1105   prior to a regular response, even if the client does not expect a 100
1106   (Continue) status message. Unexpected 1xx status responses &MAY; be
1107   ignored by a user agent.
1108</t>
1109<t>
1110   Proxies &MUST; forward 1xx responses, unless the connection between the
1111   proxy and its client has been closed, or unless the proxy itself
1112   requested the generation of the 1xx response. (For example, if a
1113   proxy adds a "Expect: 100-continue" field when it forwards a request,
1114   then it need not forward the corresponding 100 (Continue)
1115   response(s).)
1116</t>
1117
1118<section title="100 Continue" anchor="status.100">
1119  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1120  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1121<t>
1122   The client &SHOULD; continue with its request. This interim response is
1123   used to inform the client that the initial part of the request has
1124   been received and has not yet been rejected by the server. The client
1125   &SHOULD; continue by sending the remainder of the request or, if the
1126   request has already been completed, ignore this response. The server
1127   &MUST; send a final response after the request has been completed. See
1128   &use100; for detailed discussion of the use and handling of this
1129   status code.
1130</t>
1131</section>
1132
1133<section title="101 Switching Protocols" anchor="status.101">
1134  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1135  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1136<t>
1137   The server understands and is willing to comply with the client's
1138   request, via the Upgrade message header field (&header-upgrade;), for a
1139   change in the application protocol being used on this connection. The
1140   server will switch protocols to those defined by the response's
1141   Upgrade header field immediately after the empty line which
1142   terminates the 101 response.
1143</t>
1144<t>
1145   The protocol &SHOULD; be switched only when it is advantageous to do
1146   so. For example, switching to a newer version of HTTP is advantageous
1147   over older versions, and switching to a real-time, synchronous
1148   protocol might be advantageous when delivering resources that use
1149   such features.
1150</t>
1151</section>
1152</section>
1153
1154<section title="Successful 2xx" anchor="status.2xx">
1155<t>
1156   This class of status code indicates that the client's request was
1157   successfully received, understood, and accepted.
1158</t>
1159
1160<section title="200 OK" anchor="status.200">
1161  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1162  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1163<t>
1164   The request has succeeded. The payload returned with the response
1165   is dependent on the method used in the request, for example:
1166  <list style="hanging">
1167    <t hangText="GET">
1168          a representation of the target resource is sent in the response;
1169    </t>
1170    <t hangText="HEAD">
1171          the same representation as GET, except without the message-body;
1172    </t>
1173    <t hangText="POST">
1174      a representation describing or containing the result of the action;
1175    </t>
1176    <t hangText="TRACE">
1177      a representation containing the request message as received by the
1178      end server.
1179    </t>
1180  </list>
1181</t>
1182<t>
1183   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1184   freshness for 200 responses.
1185</t>
1186</section>
1187
1188<section title="201 Created" anchor="status.201">
1189  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1190  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1191<t>
1192   The request has been fulfilled and has resulted in a new resource being
1193   created. The newly created resource can be referenced by the URI(s)
1194   returned in the payload of the response, with the most specific URI
1195   for the resource given by a Location header field. The response
1196   &SHOULD; include a payload containing a list of resource
1197   characteristics and location(s) from which the user or user agent can
1198   choose the one most appropriate. The payload format is specified by
1199   the media type given in the Content-Type header field. The origin
1200   server &MUST; create the resource before returning the 201 status code.
1201   If the action cannot be carried out immediately, the server &SHOULD;
1202   respond with 202 (Accepted) response instead.
1203</t>
1204<t>
1205   A 201 response &MAY; contain an ETag response header field indicating
1206   the current value of the entity-tag for the representation of the resource
1207   just created (see &header-etag;).
1208</t>
1209</section>
1210
1211<section title="202 Accepted" anchor="status.202">
1212  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1213  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1214<t>
1215   The request has been accepted for processing, but the processing has
1216   not been completed.  The request might or might not eventually be
1217   acted upon, as it might be disallowed when processing actually takes
1218   place. There is no facility for re-sending a status code from an
1219   asynchronous operation such as this.
1220</t>
1221<t>
1222   The 202 response is intentionally non-committal. Its purpose is to
1223   allow a server to accept a request for some other process (perhaps a
1224   batch-oriented process that is only run once per day) without
1225   requiring that the user agent's connection to the server persist
1226   until the process is completed. The representation returned with this
1227   response &SHOULD; include an indication of the request's current status
1228   and either a pointer to a status monitor or some estimate of when the
1229   user can expect the request to be fulfilled.
1230</t>
1231</section>
1232
1233<section title="203 Non-Authoritative Information" anchor="status.203">
1234  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1235  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1236<t>
1237   The returned metadata in the header fields is not the
1238   definitive set as available from the origin server, but is gathered
1239   from a local or a third-party copy. The set presented &MAY; be a subset
1240   or superset of the original version. For example, including local
1241   annotation information about the resource might result in a superset
1242   of the metadata known by the origin server. Use of this
1243   response code is not required and is only appropriate when the
1244   response would otherwise be 200 (OK).
1245</t>
1246<t>
1247   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1248   freshness for 203 responses.
1249</t>
1250
1251</section>
1252
1253<section title="204 No Content" anchor="status.204">
1254  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1255  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1256<t>
1257   The server has successfully fulfilled the request, but there is no
1258   additional content to return in the response payload body.  The
1259   resource metadata and representation metadata in the response message's
1260   header fields refer to the target resource
1261   and its current representation, respectively, after the requested action.
1262   For example, if a 204 status code is received in response to a PUT
1263   and the response contains an ETag header field, then the value of
1264   that field is the current entity-tag for the representation that
1265   was successfully PUT.
1266</t>
1267<t>
1268   If the client is a user agent, it &SHOULD-NOT; change its document view
1269   from that which caused the request to be sent. This response is
1270   primarily intended to allow input for actions to take place without
1271   causing a change to the user agent's active document view, although
1272   any new or updated metadata &SHOULD; be applied to the document
1273   currently in the user agent's active view.
1274</t>
1275<t>
1276   The 204 response &MUST-NOT; include a message-body, and thus is always
1277   terminated by the first empty line after the header fields.
1278</t>
1279</section>
1280
1281<section title="205 Reset Content" anchor="status.205">
1282  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1283  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1284<t>
1285   The server has fulfilled the request and the user agent &SHOULD; reset
1286   the document view which caused the request to be sent. This response
1287   is primarily intended to allow input for actions to take place via
1288   user input, followed by a clearing of the form in which the input is
1289   given so that the user can easily initiate another input action. The
1290   response &MUST-NOT; include a message-body.
1291</t>
1292</section>
1293
1294<section title="206 Partial Content" anchor="status.206">
1295  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1296  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1297  <rdf:Description>
1298    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1299  </rdf:Description>
1300<t>
1301   The server has fulfilled the partial GET request for the resource
1302   and the enclosed payload is a partial representation as defined in &status-206;.
1303</t>
1304<t>
1305   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1306   freshness for 206 responses.
1307</t>
1308</section>
1309</section>
1310
1311<section title="Redirection 3xx" anchor="status.3xx">
1312<t>
1313   This class of status code indicates that further action needs to be
1314   taken by the user agent in order to fulfill the request.  The action
1315   required &MAY; be carried out by the user agent without interaction
1316   with the user if and only if the method used in the second request is
1317   known to be "safe", as defined in <xref target="safe.methods"/>.
1318   A client &SHOULD; detect infinite redirection loops, since such loops
1319   generate network traffic for each redirection.
1320</t>
1321<x:note>
1322  <t>
1323    <x:h>Note:</x:h> An earlier version of this specification recommended a
1324    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1325    Content developers need to be aware that some clients might
1326    implement such a fixed limitation.
1327  </t>
1328</x:note>
1329
1330<section title="300 Multiple Choices" anchor="status.300">
1331  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1332  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1333<t>
1334   The target resource more than one
1335   representation, each with its own specific location, and agent-driven
1336   negotiation information (&content-negotiation;) is being provided so that
1337   the user (or user agent) can select a preferred representation by
1338   redirecting its request to that location.
1339</t>
1340<t>
1341   Unless it was a HEAD request, the response &SHOULD; include a representation
1342   containing a list of representation metadata and location(s) from
1343   which the user or user agent can choose the one most appropriate. The
1344   data format is specified by the media type given in the Content-Type
1345   header field. Depending upon the format and the capabilities of
1346   the user agent, selection of the most appropriate choice &MAY; be
1347   performed automatically. However, this specification does not define
1348   any standard for such automatic selection.
1349</t>
1350<t>
1351   If the server has a preferred choice of representation, it &SHOULD;
1352   include the specific URI for that representation in the Location
1353   field; user agents &MAY; use the Location field value for automatic
1354   redirection.
1355</t>
1356<t>
1357   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1358   freshness for 300 responses.
1359</t>
1360
1361</section>
1362
1363<section title="301 Moved Permanently" anchor="status.301">
1364  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1365  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1366<t>
1367   The target resource has been assigned a new permanent URI and any
1368   future references to this resource &SHOULD; use one of the returned
1369   URIs.  Clients with link editing capabilities ought to automatically
1370   re-link references to the effective request URI to one or more of the new
1371   references returned by the server, where possible.
1372</t>
1373<t>
1374   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1375   freshness for 301 responses.
1376</t>
1377<t>
1378   The new permanent URI &SHOULD; be given by the Location field in the
1379   response. Unless the request method was HEAD, the representation of the
1380   response &SHOULD; contain a short hypertext note with a hyperlink to
1381   the new URI(s).
1382</t>
1383<t>
1384   If the 301 status code is received in response to a request method
1385   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1386   then the request &MAY; be automatically redirected by the user agent without
1387   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1388   request unless it can be confirmed by the user, since this might
1389   change the conditions under which the request was issued.
1390</t>
1391<x:note>
1392  <t>
1393    <x:h>Note:</x:h> When automatically redirecting a POST request after
1394    receiving a 301 status code, some existing HTTP/1.0 user agents
1395    will erroneously change it into a GET request.
1396  </t>
1397</x:note>
1398</section>
1399
1400<section title="302 Found" anchor="status.302">
1401  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1402  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1403<t>
1404   The target resource resides temporarily under a different URI.
1405   Since the redirection might be altered on occasion, the client &SHOULD;
1406   continue to use the effective request URI for future requests.
1407</t>
1408<t>
1409   The temporary URI &SHOULD; be given by the Location field in the
1410   response. Unless the request method was HEAD, the representation of the
1411   response &SHOULD; contain a short hypertext note with a hyperlink to
1412   the new URI(s).
1413</t>
1414<t>
1415   If the 302 status code is received in response to a request method
1416   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1417   then the request &MAY; be automatically redirected by the user agent without
1418   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1419   request unless it can be confirmed by the user, since this might
1420   change the conditions under which the request was issued.
1421</t>
1422<x:note>
1423  <t>
1424    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1425    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1426    specify that the client is not allowed to change the method on the
1427    redirected request.  However, most existing user agent implementations
1428    treat 302 as if it were a 303 response, performing a GET on the Location
1429    field-value regardless of the original request method. Therefore, a
1430    previous version of this specification
1431    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1432    status codes
1433    <xref target="status.303" format="none">303</xref> and
1434    <xref target="status.307" format="none">307</xref> for servers that wish
1435    to make unambiguously clear which kind of reaction is expected of the
1436    client.
1437  </t>
1438</x:note>
1439</section>
1440
1441<section title="303 See Other" anchor="status.303">
1442  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1443  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1444<t>
1445   The server directs the user agent to a different resource, indicated
1446   by a URI in the Location header field, that provides an indirect
1447   response to the original request.  The user agent &MAY; perform a GET
1448   request on the URI in the Location field in order to obtain a
1449   representation corresponding to the response, be redirected again,
1450   or end with an error status.  The Location URI is not a substitute
1451   reference for the effective request URI.
1452</t>
1453<t>
1454   The 303 status code is generally applicable to any HTTP method.  It is
1455   primarily used to allow the output of a POST action to redirect
1456   the user agent to a selected resource, since doing so provides the
1457   information corresponding to the POST response in a form that
1458   can be separately identified, bookmarked, and cached independent
1459   of the original request.
1460</t>
1461<t>
1462   A 303 response to a GET request indicates that the requested
1463   resource does not have a representation of its own that can be
1464   transferred by the server over HTTP.  The Location URI indicates a
1465   resource that is descriptive of the target resource, such that the
1466   follow-on representation might be useful to recipients without
1467   implying that it adequately represents the target resource.
1468   Note that answers to the questions of what can be represented, what
1469   representations are adequate, and what might be a useful description
1470   are outside the scope of HTTP and thus entirely determined by the
1471   URI owner(s).
1472</t>
1473<t>
1474   Except for responses to a HEAD request, the representation of a 303
1475   response &SHOULD; contain a short hypertext note with a hyperlink
1476   to the Location URI.
1477</t>
1478</section>
1479
1480<section title="304 Not Modified" anchor="status.304">
1481  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1482  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1483  <rdf:Description>
1484    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1485  </rdf:Description>
1486<t>
1487   The response to the request has not been modified since the conditions
1488   indicated by the client's conditional GET request, as defined in &status-304;.
1489</t>
1490</section>
1491
1492<section title="305 Use Proxy" anchor="status.305">
1493  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1494  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1495<t>
1496   The 305 status code was defined in a previous version of this specification
1497   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1498</t>
1499</section>
1500
1501<section title="306 (Unused)" anchor="status.306">
1502  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1503  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1504<t>
1505   The 306 status code was used in a previous version of the
1506   specification, is no longer used, and the code is reserved.
1507</t>
1508</section>
1509
1510<section title="307 Temporary Redirect" anchor="status.307">
1511  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1512  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1513<t>
1514   The target resource resides temporarily under a different URI.
1515   Since the redirection can change over time, the client &SHOULD;
1516   continue to use the effective request URI for future requests.
1517</t>
1518<t>
1519   The temporary URI &SHOULD; be given by the Location field in the
1520   response. Unless the request method was HEAD, the representation of the
1521   response &SHOULD; contain a short hypertext note with a hyperlink to
1522   the new URI(s) , since many pre-HTTP/1.1 user agents do not
1523   understand the 307 status code. Therefore, the note &SHOULD; contain the
1524   information necessary for a user to repeat the original request on
1525   the new URI.
1526</t>
1527<t>
1528   If the 307 status code is received in response to a request method
1529   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1530   then the request &MAY; be automatically redirected by the user agent without
1531   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1532   request unless it can be confirmed by the user, since this might
1533   change the conditions under which the request was issued.
1534</t>
1535</section>
1536</section>
1537
1538<section title="Client Error 4xx" anchor="status.4xx">
1539<t>
1540   The 4xx class of status code is intended for cases in which the
1541   client seems to have erred. Except when responding to a HEAD request,
1542   the server &SHOULD; include a representation containing an explanation of the
1543   error situation, and whether it is a temporary or permanent
1544   condition. These status codes are applicable to any request method.
1545   User agents &SHOULD; display any included representation to the user.
1546</t>
1547<t>
1548   If the client is sending data, a server implementation using TCP
1549   &SHOULD; be careful to ensure that the client acknowledges receipt of
1550   the packet(s) containing the response, before the server closes the
1551   input connection. If the client continues sending data to the server
1552   after the close, the server's TCP stack will send a reset packet to
1553   the client, which might erase the client's unacknowledged input buffers
1554   before they can be read and interpreted by the HTTP application.
1555</t>
1556
1557<section title="400 Bad Request" anchor="status.400">
1558  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1559  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1560<t>
1561   The request could not be understood by the server due to malformed
1562   syntax. The client &SHOULD-NOT; repeat the request without
1563   modifications.
1564</t>
1565</section>
1566
1567<section title="401 Unauthorized" anchor="status.401">
1568  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1569  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1570  <rdf:Description>
1571    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part7</redirects-to>
1572  </rdf:Description>
1573<t>
1574   The request requires user authentication (see &status-401;).
1575</t>
1576</section>
1577
1578<section title="402 Payment Required" anchor="status.402">
1579  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1580  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1581<t>
1582   This code is reserved for future use.
1583</t>
1584</section>
1585
1586<section title="403 Forbidden" anchor="status.403">
1587  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1588  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1589<t>
1590   The server understood the request, but is refusing to fulfill it.
1591   Authorization will not help and the request &SHOULD-NOT;  be repeated.
1592   If the request method was not HEAD and the server wishes to make
1593   public why the request has not been fulfilled, it &SHOULD; describe the
1594   reason for the refusal in the representation.  If the server does not wish to
1595   make this information available to the client, the status code 404
1596   (Not Found) can be used instead.
1597</t>
1598</section>
1599
1600<section title="404 Not Found" anchor="status.404">
1601  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1602  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1603<t>
1604   The server has not found anything matching the effective request URI. No
1605   indication is given of whether the condition is temporary or
1606   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1607   knows, through some internally configurable mechanism, that an old
1608   resource is permanently unavailable and has no forwarding address.
1609   This status code is commonly used when the server does not wish to
1610   reveal exactly why the request has been refused, or when no other
1611   response is applicable.
1612</t>
1613</section>
1614
1615<section title="405 Method Not Allowed" anchor="status.405">
1616  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1617  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1618<t>
1619   The method specified in the Request-Line is not allowed for the target
1620   resource. The response &MUST; include an
1621   Allow header containing a list of valid methods for the requested
1622   resource.
1623</t>
1624</section>
1625
1626<section title="406 Not Acceptable" anchor="status.406">
1627  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1628  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1629<t>
1630   The resource identified by the request is only capable of generating
1631   response representations which have content characteristics not acceptable
1632   according to the accept headers sent in the request.
1633</t>
1634<t>
1635   Unless it was a HEAD request, the response &SHOULD; include a representation
1636   containing a list of available representation characteristics and location(s)
1637   from which the user or user agent can choose the one most
1638   appropriate. The data format is specified by the media type given
1639   in the Content-Type header field. Depending upon the format and the
1640   capabilities of the user agent, selection of the most appropriate
1641   choice &MAY; be performed automatically. However, this specification
1642   does not define any standard for such automatic selection.
1643</t>
1644<x:note>
1645  <t>
1646    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1647    not acceptable according to the accept headers sent in the
1648    request. In some cases, this might even be preferable to sending a
1649    406 response. User agents are encouraged to inspect the headers of
1650    an incoming response to determine if it is acceptable.
1651  </t>
1652</x:note>
1653<t>
1654   If the response could be unacceptable, a user agent &SHOULD;
1655   temporarily stop receipt of more data and query the user for a
1656   decision on further actions.
1657</t>
1658</section>
1659
1660<section title="407 Proxy Authentication Required" anchor="status.407">
1661  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1662  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1663<t>
1664   This code is similar to 401 (Unauthorized), but indicates that the
1665   client must first authenticate itself with the proxy (see &status-407;).
1666</t>
1667</section>
1668
1669<section title="408 Request Timeout" anchor="status.408">
1670  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1671  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1672<t>
1673   The client did not produce a request within the time that the server
1674   was prepared to wait. The client &MAY; repeat the request without
1675   modifications at any later time.
1676</t>
1677</section>
1678
1679<section title="409 Conflict" anchor="status.409">
1680  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1681  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1682<t>
1683   The request could not be completed due to a conflict with the current
1684   state of the resource. This code is only allowed in situations where
1685   it is expected that the user might be able to resolve the conflict
1686   and resubmit the request. The response body &SHOULD; include enough
1687   information for the user to recognize the source of the conflict.
1688   Ideally, the response representation would include enough information for the
1689   user or user agent to fix the problem; however, that might not be
1690   possible and is not required.
1691</t>
1692<t>
1693   Conflicts are most likely to occur in response to a PUT request. For
1694   example, if versioning were being used and the representation being PUT
1695   included changes to a resource which conflict with those made by an
1696   earlier (third-party) request, the server might use the 409 response
1697   to indicate that it can't complete the request. In this case, the
1698   response representation would likely contain a list of the differences
1699   between the two versions in a format defined by the response
1700   Content-Type.
1701</t>
1702</section>
1703
1704<section title="410 Gone" anchor="status.410">
1705  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1706  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1707<t>
1708   The target resource is no longer available at the server and no
1709   forwarding address is known. This condition is expected to be
1710   considered permanent. Clients with link editing capabilities &SHOULD;
1711   delete references to the effective request URI after user approval. If the
1712   server does not know, or has no facility to determine, whether or not
1713   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1714   used instead.
1715</t>
1716<t>
1717   The 410 response is primarily intended to assist the task of web
1718   maintenance by notifying the recipient that the resource is
1719   intentionally unavailable and that the server owners desire that
1720   remote links to that resource be removed. Such an event is common for
1721   limited-time, promotional services and for resources belonging to
1722   individuals no longer working at the server's site. It is not
1723   necessary to mark all permanently unavailable resources as "gone" or
1724   to keep the mark for any length of time -- that is left to the
1725   discretion of the server owner.
1726</t>
1727<t>
1728   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine freshness
1729   for 410 responses.
1730</t>
1731
1732</section>
1733
1734<section title="411 Length Required" anchor="status.411">
1735  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1736  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1737<t>
1738   The server refuses to accept the request without a defined Content-Length.
1739   The client &MAY; repeat the request if it adds a valid
1740   Content-Length header field containing the length of the message-body
1741   in the request message.
1742</t>
1743</section>
1744
1745<section title="412 Precondition Failed" anchor="status.412">
1746  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1747  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1748  <rdf:Description>
1749    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1750  </rdf:Description>
1751<t>
1752   The precondition given in one or more of the request-header fields
1753   evaluated to false when it was tested on the server, as defined in
1754   &status-412;.
1755</t>
1756</section>
1757
1758<section title="413 Request Entity Too Large" anchor="status.413">
1759  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1760  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1761<t>
1762   The server is refusing to process a request because the request
1763   representation is larger than the server is willing or able to process. The
1764   server &MAY; close the connection to prevent the client from continuing
1765   the request.
1766</t>
1767<t>
1768   If the condition is temporary, the server &SHOULD; include a Retry-After
1769   header field to indicate that it is temporary and after what
1770   time the client &MAY; try again.
1771</t>
1772</section>
1773
1774<section title="414 URI Too Long" anchor="status.414">
1775  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1776  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1777<t>
1778   The server is refusing to service the request because the effective request URI
1779   is longer than the server is willing to interpret. This rare
1780   condition is only likely to occur when a client has improperly
1781   converted a POST request to a GET request with long query
1782   information, when the client has descended into a URI "black hole" of
1783   redirection (e.g., a redirected URI prefix that points to a suffix of
1784   itself), or when the server is under attack by a client attempting to
1785   exploit security holes present in some servers using fixed-length
1786   buffers for reading or manipulating the effective request URI.
1787</t>
1788</section>
1789
1790<section title="415 Unsupported Media Type" anchor="status.415">
1791  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1792  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1793<t>
1794   The server is refusing to service the request because the representation of
1795   the request is in a format not supported by the target resource
1796   for the requested method.
1797</t>
1798</section>
1799
1800<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1801  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1802  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1803  <rdf:Description>
1804    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1805  </rdf:Description>
1806<t>
1807   The request included a Range request-header field (&header-range;) and none of
1808   the range-specifier values in this field overlap the current extent
1809   of the selected resource. See &status-416;.
1810</t>
1811</section>
1812
1813<section title="417 Expectation Failed" anchor="status.417">
1814  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
1815  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
1816<t>
1817   The expectation given in an Expect request-header field (see <xref target="header.expect"/>)
1818   could not be met by this server, or, if the server is a proxy,
1819   the server has unambiguous evidence that the request could not be met
1820   by the next-hop server.
1821</t>
1822</section>
1823</section>
1824
1825<section title="Server Error 5xx" anchor="status.5xx">
1826<t>
1827   Response status codes beginning with the digit "5" indicate cases in
1828   which the server is aware that it has erred or is incapable of
1829   performing the request. Except when responding to a HEAD request, the
1830   server &SHOULD; include a representation containing an explanation of the
1831   error situation, and whether it is a temporary or permanent
1832   condition. User agents &SHOULD; display any included representation to the
1833   user. These response codes are applicable to any request method.
1834</t>
1835
1836<section title="500 Internal Server Error" anchor="status.500">
1837  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
1838  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
1839<t>
1840   The server encountered an unexpected condition which prevented it
1841   from fulfilling the request.
1842</t>
1843</section>
1844
1845<section title="501 Not Implemented" anchor="status.501">
1846  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
1847  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
1848<t>
1849   The server does not support the functionality required to fulfill the
1850   request. This is the appropriate response when the server does not
1851   recognize the request method and is not capable of supporting it for
1852   any resource.
1853</t>
1854</section>
1855
1856<section title="502 Bad Gateway" anchor="status.502">
1857  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
1858  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
1859<t>
1860   The server, while acting as a gateway or proxy, received an invalid
1861   response from the upstream server it accessed in attempting to
1862   fulfill the request.
1863</t>
1864</section>
1865
1866<section title="503 Service Unavailable" anchor="status.503">
1867  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
1868  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
1869<t>
1870   The server is currently unable to handle the request due to a
1871   temporary overloading or maintenance of the server. The implication
1872   is that this is a temporary condition which will be alleviated after
1873   some delay. If known, the length of the delay &MAY; be indicated in a
1874   Retry-After header. If no Retry-After is given, the client &SHOULD;
1875   handle the response as it would for a 500 response.
1876</t>
1877<x:note>
1878  <t>
1879    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
1880    server must use it when becoming overloaded. Some servers might wish
1881    to simply refuse the connection.
1882  </t>
1883</x:note>
1884</section>
1885
1886<section title="504 Gateway Timeout" anchor="status.504">
1887  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
1888  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
1889<t>
1890   The server, while acting as a gateway or proxy, did not receive a
1891   timely response from the upstream server specified by the URI (e.g.,
1892   HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
1893   to access in attempting to complete the request.
1894</t>
1895<x:note>
1896  <t>
1897    <x:h>Note</x:h> to implementors: some deployed proxies are known to
1898    return 400 or 500 when DNS lookups time out.
1899  </t>
1900</x:note>
1901</section>
1902
1903<section title="505 HTTP Version Not Supported" anchor="status.505">
1904  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
1905  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
1906<t>
1907   The server does not support, or refuses to support, the protocol
1908   version that was used in the request message. The server is
1909   indicating that it is unable or unwilling to complete the request
1910   using the same major version as the client, as described in &http-version;,
1911   other than with this error message. The response &SHOULD; contain
1912   a representation describing why that version is not supported and what other
1913   protocols are supported by that server.
1914</t>
1915
1916</section>
1917</section>
1918</section>
1919
1920
1921<section title="Header Field Definitions" anchor="header.fields">
1922<t>
1923   This section defines the syntax and semantics of HTTP/1.1 header fields
1924   related to request and response semantics.
1925</t>
1926
1927<section title="Allow" anchor="header.allow">
1928  <iref primary="true" item="Allow header" x:for-anchor=""/>
1929  <iref primary="true" item="Headers" subitem="Allow" x:for-anchor=""/>
1930  <x:anchor-alias value="Allow"/>
1931  <x:anchor-alias value="Allow-v"/>
1932<t>
1933   The "Allow" response-header field lists the set of methods advertised as
1934   supported by the target resource. The purpose of
1935   this field is strictly to inform the recipient of valid methods
1936   associated with the resource.
1937</t>
1938<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/><iref primary="true" item="Grammar" subitem="Allow-v"/>
1939  <x:ref>Allow</x:ref>   = "Allow" ":" <x:ref>OWS</x:ref> <x:ref>Allow-v</x:ref>
1940  <x:ref>Allow-v</x:ref> = #<x:ref>Method</x:ref>
1941</artwork></figure>
1942<t>
1943      Example of use:
1944</t>
1945<figure><artwork type="example">
1946  Allow: GET, HEAD, PUT
1947</artwork></figure>
1948<t>
1949      The actual set of allowed methods is defined
1950      by the origin server at the time of each request.
1951</t>
1952<t>
1953      A proxy &MUST-NOT; modify the Allow header field even if it does not
1954      understand all the methods specified, since the user agent might
1955      have other means of communicating with the origin server.
1956</t>
1957</section>
1958
1959<section title="Expect" anchor="header.expect">
1960  <iref primary="true" item="Expect header" x:for-anchor=""/>
1961  <iref primary="true" item="Headers" subitem="Expect" x:for-anchor=""/>
1962  <x:anchor-alias value="Expect"/>
1963  <x:anchor-alias value="Expect-v"/>
1964  <x:anchor-alias value="expectation"/>
1965  <x:anchor-alias value="expectation-extension"/>
1966  <x:anchor-alias value="expect-params"/>
1967<t>
1968   The "Expect" request-header field is used to indicate that particular
1969   server behaviors are required by the client.
1970</t>
1971<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"/>
1972  <x:ref>Expect</x:ref>       = "Expect" ":" <x:ref>OWS</x:ref> <x:ref>Expect-v</x:ref>
1973  <x:ref>Expect-v</x:ref>     = 1#<x:ref>expectation</x:ref>
1974 
1975  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
1976  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
1977                           *<x:ref>expect-params</x:ref> ]
1978  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
1979</artwork></figure>
1980<t>
1981   A server that does not understand or is unable to comply with any of
1982   the expectation values in the Expect field of a request &MUST; respond
1983   with appropriate error status code. The server &MUST; respond with a 417
1984   (Expectation Failed) status code if any of the expectations cannot be met
1985   or, if there are other problems with the request, some other 4xx
1986   status code.
1987</t>
1988<t>
1989   This header field is defined with extensible syntax to allow for
1990   future extensions. If a server receives a request containing an
1991   Expect field that includes an expectation-extension that it does not
1992   support, it &MUST; respond with a 417 (Expectation Failed) status code.
1993</t>
1994<t>
1995   Comparison of expectation values is case-insensitive for unquoted
1996   tokens (including the 100-continue token), and is case-sensitive for
1997   quoted-string expectation-extensions.
1998</t>
1999<t>
2000   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
2001   return a 417 (Expectation Failed) status code if it receives a request
2002   with an expectation that it cannot meet. However, the Expect
2003   request-header itself is end-to-end; it &MUST; be forwarded if the
2004   request is forwarded.
2005</t>
2006<t>
2007   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
2008   Expect header.
2009</t>
2010<t>
2011   See &use100; for the use of the 100 (Continue) status code.
2012</t>
2013</section>
2014
2015<section title="From" anchor="header.from">
2016  <iref primary="true" item="From header" x:for-anchor=""/>
2017  <iref primary="true" item="Headers" subitem="From" x:for-anchor=""/>
2018  <x:anchor-alias value="From"/>
2019  <x:anchor-alias value="From-v"/>
2020  <x:anchor-alias value="mailbox"/>
2021<t>
2022   The "From" request-header field, if given, &SHOULD; contain an Internet
2023   e-mail address for the human user who controls the requesting user
2024   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
2025   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
2026</t>
2027<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/><iref primary="true" item="Grammar" subitem="From-v"/>
2028  <x:ref>From</x:ref>    = "From" ":" <x:ref>OWS</x:ref> <x:ref>From-v</x:ref>
2029  <x:ref>From-v</x:ref>  = <x:ref>mailbox</x:ref>
2030 
2031  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
2032</artwork></figure>
2033<t>
2034   An example is:
2035</t>
2036<figure><artwork type="example">
2037  From: webmaster@example.org
2038</artwork></figure>
2039<t>
2040   This header field &MAY; be used for logging purposes and as a means for
2041   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
2042   be used as an insecure form of access protection. The interpretation
2043   of this field is that the request is being performed on behalf of the
2044   person given, who accepts responsibility for the method performed. In
2045   particular, robot agents &SHOULD; include this header so that the
2046   person responsible for running the robot can be contacted if problems
2047   occur on the receiving end.
2048</t>
2049<t>
2050   The Internet e-mail address in this field &MAY; be separate from the
2051   Internet host which issued the request. For example, when a request
2052   is passed through a proxy the original issuer's address &SHOULD; be
2053   used.
2054</t>
2055<t>
2056   The client &SHOULD-NOT;  send the From header field without the user's
2057   approval, as it might conflict with the user's privacy interests or
2058   their site's security policy. It is strongly recommended that the
2059   user be able to disable, enable, and modify the value of this field
2060   at any time prior to a request.
2061</t>
2062</section>
2063
2064<section title="Location" anchor="header.location">
2065  <iref primary="true" item="Location header" x:for-anchor=""/>
2066  <iref primary="true" item="Headers" subitem="Location" x:for-anchor=""/>
2067  <x:anchor-alias value="Location"/>
2068  <x:anchor-alias value="Location-v"/>
2069<t>
2070   The "Location" response-header field is used to identify a newly created
2071   resource, or to redirect the recipient to a different location for
2072   completion of the request.
2073</t>
2074<t>
2075   For 201 (Created) responses, the Location is the URI of the new resource
2076   which was created by the request. For 3xx responses, the location &SHOULD;
2077   indicate the server's preferred URI for automatic redirection to the
2078   resource.
2079</t>
2080<t>
2081   The field value consists of a single URI-reference. When it has the form
2082   of a relative reference (<xref target="RFC3986" x:fmt="," x:sec="4.2"/>),
2083   the final value is computed by resolving it against the effective request
2084   URI (<xref target="RFC3986" x:fmt="," x:sec="5"/>).
2085</t>
2086<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/><iref primary="true" item="Grammar" subitem="Location-v"/>
2087  <x:ref>Location</x:ref>       = "Location" ":" <x:ref>OWS</x:ref> <x:ref>Location-v</x:ref>
2088  <x:ref>Location-v</x:ref>     = <x:ref>URI-reference</x:ref>
2089</artwork></figure>
2090<figure>
2091<preamble>Examples are:</preamble><!--DO NOT DARE changing the vertical WSP below, it's necessary this way for xml2rfc-->
2092<artwork type="example">
2093  Location: http://www.example.org/pub/WWW/People.html#tim
2094</artwork></figure><figure><artwork type="example">  Location: /index.html
2095</artwork></figure>
2096<t>
2097   There are circumstances in which a fragment identifier in a Location URI
2098   would not be appropriate:
2099   <list style="symbols">
2100      <t>With a 201 Created response, because in this usage the Location header
2101      specifies the URI for the entire created resource.</t>
2102      <t>With 305 Use Proxy.</t>
2103   </list>
2104</t>
2105<x:note>
2106  <t>
2107    <x:h>Note:</x:h> This specification does not define precedence rules
2108    for the case where the original URI, as navigated to by the user
2109    agent, and the Location header field value both contain fragment
2110    identifiers.
2111  </t>
2112</x:note>
2113<x:note>
2114  <t>
2115    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2116    from Location in that the Content-Location identifies the most specific
2117    resource corresponding to the enclosed representation.
2118    It is therefore possible for a response to contain header fields for
2119    both Location and Content-Location.
2120  </t>
2121</x:note>
2122</section>
2123
2124<section title="Max-Forwards" anchor="header.max-forwards">
2125  <iref primary="true" item="Max-Forwards header" x:for-anchor=""/>
2126  <iref primary="true" item="Headers" subitem="Max-Forwards" x:for-anchor=""/>
2127  <x:anchor-alias value="Max-Forwards"/>
2128  <x:anchor-alias value="Max-Forwards-v"/>
2129<t>
2130   The "Max-Forwards" request-header field provides a mechanism with the
2131   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>)
2132   methods to limit the number of times that the request is forwarded by
2133   proxies or gateways. This can be useful when the client is attempting to
2134   trace a request which appears to be failing or looping in mid-chain.
2135</t>
2136<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/><iref primary="true" item="Grammar" subitem="Max-Forwards-v"/>
2137  <x:ref>Max-Forwards</x:ref>   = "Max-Forwards" ":" <x:ref>OWS</x:ref> <x:ref>Max-Forwards-v</x:ref>
2138  <x:ref>Max-Forwards-v</x:ref> = 1*<x:ref>DIGIT</x:ref>
2139</artwork></figure>
2140<t>
2141   The Max-Forwards value is a decimal integer indicating the remaining
2142   number of times this request message can be forwarded.
2143</t>
2144<t>
2145   Each proxy or gateway recipient of a TRACE or OPTIONS request
2146   containing a Max-Forwards header field &MUST; check and update its
2147   value prior to forwarding the request. If the received value is zero
2148   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2149   respond as the final recipient. If the received Max-Forwards value is
2150   greater than zero, then the forwarded message &MUST; contain an updated
2151   Max-Forwards field with a value decremented by one (1).
2152</t>
2153<t>
2154   The Max-Forwards header field &MAY; be ignored for all other methods
2155   defined by this specification and for any extension methods for which
2156   it is not explicitly referred to as part of that method definition.
2157</t>
2158</section>
2159
2160<section title="Referer" anchor="header.referer">
2161  <iref primary="true" item="Referer header" x:for-anchor=""/>
2162  <iref primary="true" item="Headers" subitem="Referer" x:for-anchor=""/>
2163  <x:anchor-alias value="Referer"/>
2164  <x:anchor-alias value="Referer-v"/>
2165<t>
2166   The "Referer" [sic] request-header field allows the client to specify the
2167   URI of the resource from which the effective request URI was obtained (the
2168   "referrer", although the header field is misspelled.).
2169</t>
2170<t>
2171   The Referer header allows servers to generate lists of back-links to
2172   resources for interest, logging, optimized caching, etc. It also allows
2173   obsolete or mistyped links to be traced for maintenance. Some servers use
2174   Referer as a means of controlling where they allow links from (so-called
2175   "deep linking"), but legitimate requests do not always
2176   contain a Referer header field.
2177</t>
2178<t>
2179   If the effective request URI was obtained from a source that does not have its own
2180   URI (e.g., input from the user keyboard), the Referer field &MUST; either be
2181   sent with the value "about:blank", or not be sent at all. Note that this
2182   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2183</t>
2184<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/><iref primary="true" item="Grammar" subitem="Referer-v"/>
2185  <x:ref>Referer</x:ref>        = "Referer" ":" <x:ref>OWS</x:ref> <x:ref>Referer-v</x:ref>
2186  <x:ref>Referer-v</x:ref>      = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2187</artwork></figure>
2188<t>
2189   Example:
2190</t>
2191<figure><artwork type="example">
2192  Referer: http://www.example.org/hypertext/Overview.html
2193</artwork></figure>
2194<t>
2195   If the field value is a relative URI, it &SHOULD; be interpreted
2196   relative to the effective request URI. The URI &MUST-NOT; include a fragment. See
2197   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2198</t>
2199</section>
2200
2201<section title="Retry-After" anchor="header.retry-after">
2202  <iref primary="true" item="Retry-After header" x:for-anchor=""/>
2203  <iref primary="true" item="Headers" subitem="Retry-After" x:for-anchor=""/>
2204  <x:anchor-alias value="Retry-After"/>
2205  <x:anchor-alias value="Retry-After-v"/>
2206<t>
2207   The response-header "Retry-After" field can be used with a 503 (Service
2208   Unavailable) response to indicate how long the service is expected to
2209   be unavailable to the requesting client. This field &MAY; also be used
2210   with any 3xx (Redirection) response to indicate the minimum time the
2211   user-agent is asked wait before issuing the redirected request.
2212</t>
2213<t>
2214   The value of this field can be either an HTTP-date or an integer number
2215   of seconds (in decimal) after the time of the response.
2216</t>
2217<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/><iref primary="true" item="Grammar" subitem="Retry-After-v"/>
2218  <x:ref>Retry-After</x:ref>   = "Retry-After" ":" <x:ref>OWS</x:ref> <x:ref>Retry-After-v</x:ref>
2219  <x:ref>Retry-After-v</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2220</artwork></figure>
2221<t anchor="rule.delta-seconds">
2222  <x:anchor-alias value="delta-seconds"/>
2223   Time spans are non-negative decimal integers, representing time in
2224   seconds.
2225</t>
2226<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2227  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2228</artwork></figure>
2229<t>
2230   Two examples of its use are
2231</t>
2232<figure><artwork type="example">
2233  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2234  Retry-After: 120
2235</artwork></figure>
2236<t>
2237   In the latter example, the delay is 2 minutes.
2238</t>
2239</section>
2240
2241<section title="Server" anchor="header.server">
2242  <iref primary="true" item="Server header" x:for-anchor=""/>
2243  <iref primary="true" item="Headers" subitem="Server" x:for-anchor=""/>
2244  <x:anchor-alias value="Server"/>
2245  <x:anchor-alias value="Server-v"/>
2246<t>
2247   The "Server" response-header field contains information about the
2248   software used by the origin server to handle the request.
2249</t>
2250<t>
2251   The field can contain multiple product tokens (&product-tokens;) and
2252   comments (&header-fields;) identifying the server and any significant
2253   subproducts. The product tokens are listed in order of their significance
2254   for identifying the application.
2255</t>
2256<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/><iref primary="true" item="Grammar" subitem="Server-v"/>
2257  <x:ref>Server</x:ref>         = "Server" ":" <x:ref>OWS</x:ref> <x:ref>Server-v</x:ref>
2258  <x:ref>Server-v</x:ref>       = <x:ref>product</x:ref>
2259                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2260</artwork></figure>
2261<t>
2262   Example:
2263</t>
2264<figure><artwork type="example">
2265  Server: CERN/3.0 libwww/2.17
2266</artwork></figure>
2267<t>
2268   If the response is being forwarded through a proxy, the proxy
2269   application &MUST-NOT; modify the Server response-header. Instead, it
2270   &MUST; include a Via field (as described in &header-via;).
2271</t>
2272<x:note>
2273  <t>
2274    <x:h>Note:</x:h> Revealing the specific software version of the server might
2275    allow the server machine to become more vulnerable to attacks
2276    against software that is known to contain security holes. Server
2277    implementors are encouraged to make this field a configurable
2278    option.
2279  </t>
2280</x:note>
2281</section>
2282
2283<section title="User-Agent" anchor="header.user-agent">
2284  <iref primary="true" item="User-Agent header" x:for-anchor=""/>
2285  <iref primary="true" item="Headers" subitem="User-Agent" x:for-anchor=""/>
2286  <x:anchor-alias value="User-Agent"/>
2287  <x:anchor-alias value="User-Agent-v"/>
2288<t>
2289   The "User-Agent" request-header field contains information about the
2290   user agent originating the request. This is for statistical purposes,
2291   the tracing of protocol violations, and automated recognition of user
2292   agents for the sake of tailoring responses to avoid particular user
2293   agent limitations.
2294</t>
2295<t>
2296   User agents &SHOULD; include this field with requests. The field can contain
2297   multiple product tokens (&product-tokens;) and comments (&header-fields;)
2298   identifying the agent and any subproducts which form a significant part of
2299   the user agent. By convention, the product tokens are listed in order of
2300   their significance for identifying the application.
2301</t>
2302<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/><iref primary="true" item="Grammar" subitem="User-Agent-v"/>
2303  <x:ref>User-Agent</x:ref>     = "User-Agent" ":" <x:ref>OWS</x:ref> <x:ref>User-Agent-v</x:ref>
2304  <x:ref>User-Agent-v</x:ref>   = <x:ref>product</x:ref>
2305                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2306</artwork></figure>
2307<t>
2308   Example:
2309</t>
2310<figure><artwork type="example">
2311  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2312</artwork></figure>
2313</section>
2314
2315</section>
2316
2317<section title="IANA Considerations" anchor="IANA.considerations">
2318
2319<section title="Method Registry" anchor="method.registration">
2320<t>
2321  The registration procedure for HTTP Methods is defined by
2322  <xref target="method.registry"/> of this document.
2323</t>
2324<t>
2325   The HTTP Method Registry shall be created at <eref target="http://www.iana.org/assignments/http-methods"/>
2326   and be populated with the registrations below:
2327</t>
2328<?BEGININC p2-semantics.iana-methods ?>
2329<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2330<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2331   <ttcol>Method</ttcol>
2332   <ttcol>Safe</ttcol>
2333   <ttcol>Reference</ttcol>
2334   <c>CONNECT</c>
2335   <c>no</c>
2336   <c>
2337      <xref target="CONNECT"/>
2338   </c>
2339   <c>DELETE</c>
2340   <c>no</c>
2341   <c>
2342      <xref target="DELETE"/>
2343   </c>
2344   <c>GET</c>
2345   <c>yes</c>
2346   <c>
2347      <xref target="GET"/>
2348   </c>
2349   <c>HEAD</c>
2350   <c>yes</c>
2351   <c>
2352      <xref target="HEAD"/>
2353   </c>
2354   <c>OPTIONS</c>
2355   <c>yes</c>
2356   <c>
2357      <xref target="OPTIONS"/>
2358   </c>
2359   <c>POST</c>
2360   <c>no</c>
2361   <c>
2362      <xref target="POST"/>
2363   </c>
2364   <c>PUT</c>
2365   <c>no</c>
2366   <c>
2367      <xref target="PUT"/>
2368   </c>
2369   <c>TRACE</c>
2370   <c>yes</c>
2371   <c>
2372      <xref target="TRACE"/>
2373   </c>
2374</texttable>
2375<!--(END)-->
2376<?ENDINC p2-semantics.iana-methods ?>
2377</section>
2378
2379<section title="Status Code Registry" anchor="status.code.registration">
2380<t>
2381   The registration procedure for HTTP Status Codes -- previously defined
2382   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> -- is now defined
2383   by <xref target="status.code.registry"/> of this document.
2384</t>
2385<t>
2386   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2387   shall be updated with the registrations below:
2388</t>
2389<?BEGININC p2-semantics.iana-status-codes ?>
2390<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2391<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2392   <ttcol>Value</ttcol>
2393   <ttcol>Description</ttcol>
2394   <ttcol>Reference</ttcol>
2395   <c>100</c>
2396   <c>Continue</c>
2397   <c>
2398      <xref target="status.100"/>
2399   </c>
2400   <c>101</c>
2401   <c>Switching Protocols</c>
2402   <c>
2403      <xref target="status.101"/>
2404   </c>
2405   <c>200</c>
2406   <c>OK</c>
2407   <c>
2408      <xref target="status.200"/>
2409   </c>
2410   <c>201</c>
2411   <c>Created</c>
2412   <c>
2413      <xref target="status.201"/>
2414   </c>
2415   <c>202</c>
2416   <c>Accepted</c>
2417   <c>
2418      <xref target="status.202"/>
2419   </c>
2420   <c>203</c>
2421   <c>Non-Authoritative Information</c>
2422   <c>
2423      <xref target="status.203"/>
2424   </c>
2425   <c>204</c>
2426   <c>No Content</c>
2427   <c>
2428      <xref target="status.204"/>
2429   </c>
2430   <c>205</c>
2431   <c>Reset Content</c>
2432   <c>
2433      <xref target="status.205"/>
2434   </c>
2435   <c>300</c>
2436   <c>Multiple Choices</c>
2437   <c>
2438      <xref target="status.300"/>
2439   </c>
2440   <c>301</c>
2441   <c>Moved Permanently</c>
2442   <c>
2443      <xref target="status.301"/>
2444   </c>
2445   <c>302</c>
2446   <c>Found</c>
2447   <c>
2448      <xref target="status.302"/>
2449   </c>
2450   <c>303</c>
2451   <c>See Other</c>
2452   <c>
2453      <xref target="status.303"/>
2454   </c>
2455   <c>305</c>
2456   <c>Use Proxy</c>
2457   <c>
2458      <xref target="status.305"/>
2459   </c>
2460   <c>306</c>
2461   <c>(Unused)</c>
2462   <c>
2463      <xref target="status.306"/>
2464   </c>
2465   <c>307</c>
2466   <c>Temporary Redirect</c>
2467   <c>
2468      <xref target="status.307"/>
2469   </c>
2470   <c>400</c>
2471   <c>Bad Request</c>
2472   <c>
2473      <xref target="status.400"/>
2474   </c>
2475   <c>402</c>
2476   <c>Payment Required</c>
2477   <c>
2478      <xref target="status.402"/>
2479   </c>
2480   <c>403</c>
2481   <c>Forbidden</c>
2482   <c>
2483      <xref target="status.403"/>
2484   </c>
2485   <c>404</c>
2486   <c>Not Found</c>
2487   <c>
2488      <xref target="status.404"/>
2489   </c>
2490   <c>405</c>
2491   <c>Method Not Allowed</c>
2492   <c>
2493      <xref target="status.405"/>
2494   </c>
2495   <c>406</c>
2496   <c>Not Acceptable</c>
2497   <c>
2498      <xref target="status.406"/>
2499   </c>
2500   <c>407</c>
2501   <c>Proxy Authentication Required</c>
2502   <c>
2503      <xref target="status.407"/>
2504   </c>
2505   <c>408</c>
2506   <c>Request Timeout</c>
2507   <c>
2508      <xref target="status.408"/>
2509   </c>
2510   <c>409</c>
2511   <c>Conflict</c>
2512   <c>
2513      <xref target="status.409"/>
2514   </c>
2515   <c>410</c>
2516   <c>Gone</c>
2517   <c>
2518      <xref target="status.410"/>
2519   </c>
2520   <c>411</c>
2521   <c>Length Required</c>
2522   <c>
2523      <xref target="status.411"/>
2524   </c>
2525   <c>413</c>
2526   <c>Request Entity Too Large</c>
2527   <c>
2528      <xref target="status.413"/>
2529   </c>
2530   <c>414</c>
2531   <c>URI Too Long</c>
2532   <c>
2533      <xref target="status.414"/>
2534   </c>
2535   <c>415</c>
2536   <c>Unsupported Media Type</c>
2537   <c>
2538      <xref target="status.415"/>
2539   </c>
2540   <c>417</c>
2541   <c>Expectation Failed</c>
2542   <c>
2543      <xref target="status.417"/>
2544   </c>
2545   <c>500</c>
2546   <c>Internal Server Error</c>
2547   <c>
2548      <xref target="status.500"/>
2549   </c>
2550   <c>501</c>
2551   <c>Not Implemented</c>
2552   <c>
2553      <xref target="status.501"/>
2554   </c>
2555   <c>502</c>
2556   <c>Bad Gateway</c>
2557   <c>
2558      <xref target="status.502"/>
2559   </c>
2560   <c>503</c>
2561   <c>Service Unavailable</c>
2562   <c>
2563      <xref target="status.503"/>
2564   </c>
2565   <c>504</c>
2566   <c>Gateway Timeout</c>
2567   <c>
2568      <xref target="status.504"/>
2569   </c>
2570   <c>505</c>
2571   <c>HTTP Version Not Supported</c>
2572   <c>
2573      <xref target="status.505"/>
2574   </c>
2575</texttable>
2576<!--(END)-->
2577<?ENDINC p2-semantics.iana-status-codes ?>
2578</section>
2579<section title="Header Field Registration" anchor="header.field.registration">
2580<t>
2581   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
2582   with the permanent registrations below (see <xref target="RFC3864"/>):
2583</t>
2584<?BEGININC p2-semantics.iana-headers ?>
2585<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2586<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2587   <ttcol>Header Field Name</ttcol>
2588   <ttcol>Protocol</ttcol>
2589   <ttcol>Status</ttcol>
2590   <ttcol>Reference</ttcol>
2591
2592   <c>Allow</c>
2593   <c>http</c>
2594   <c>standard</c>
2595   <c>
2596      <xref target="header.allow"/>
2597   </c>
2598   <c>Expect</c>
2599   <c>http</c>
2600   <c>standard</c>
2601   <c>
2602      <xref target="header.expect"/>
2603   </c>
2604   <c>From</c>
2605   <c>http</c>
2606   <c>standard</c>
2607   <c>
2608      <xref target="header.from"/>
2609   </c>
2610   <c>Location</c>
2611   <c>http</c>
2612   <c>standard</c>
2613   <c>
2614      <xref target="header.location"/>
2615   </c>
2616   <c>Max-Forwards</c>
2617   <c>http</c>
2618   <c>standard</c>
2619   <c>
2620      <xref target="header.max-forwards"/>
2621   </c>
2622   <c>Referer</c>
2623   <c>http</c>
2624   <c>standard</c>
2625   <c>
2626      <xref target="header.referer"/>
2627   </c>
2628   <c>Retry-After</c>
2629   <c>http</c>
2630   <c>standard</c>
2631   <c>
2632      <xref target="header.retry-after"/>
2633   </c>
2634   <c>Server</c>
2635   <c>http</c>
2636   <c>standard</c>
2637   <c>
2638      <xref target="header.server"/>
2639   </c>
2640   <c>User-Agent</c>
2641   <c>http</c>
2642   <c>standard</c>
2643   <c>
2644      <xref target="header.user-agent"/>
2645   </c>
2646</texttable>
2647<!--(END)-->
2648<?ENDINC p2-semantics.iana-headers ?>
2649<t>
2650   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2651</t>
2652</section>
2653</section>
2654
2655<section title="Security Considerations" anchor="security.considerations">
2656<t>
2657   This section is meant to inform application developers, information
2658   providers, and users of the security limitations in HTTP/1.1 as
2659   described by this document. The discussion does not include
2660   definitive solutions to the problems revealed, though it does make
2661   some suggestions for reducing security risks.
2662</t>
2663
2664<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2665<t>
2666   Like any generic data transfer protocol, HTTP cannot regulate the
2667   content of the data that is transferred, nor is there any a priori
2668   method of determining the sensitivity of any particular piece of
2669   information within the context of any given request. Therefore,
2670   applications &SHOULD; supply as much control over this information as
2671   possible to the provider of that information. Four header fields are
2672   worth special mention in this context: Server, Via, Referer and From.
2673</t>
2674<t>
2675   Revealing the specific software version of the server might allow the
2676   server machine to become more vulnerable to attacks against software
2677   that is known to contain security holes. Implementors &SHOULD; make the
2678   Server header field a configurable option.
2679</t>
2680<t>
2681   Proxies which serve as a portal through a network firewall &SHOULD;
2682   take special precautions regarding the transfer of header information
2683   that identifies the hosts behind the firewall. In particular, they
2684   &SHOULD; remove, or replace with sanitized versions, any Via fields
2685   generated behind the firewall.
2686</t>
2687<t>
2688   The Referer header allows reading patterns to be studied and reverse
2689   links drawn. Although it can be very useful, its power can be abused
2690   if user details are not separated from the information contained in
2691   the Referer. Even when the personal information has been removed, the
2692   Referer header might indicate a private document's URI whose
2693   publication would be inappropriate.
2694</t>
2695<t>
2696   The information sent in the From field might conflict with the user's
2697   privacy interests or their site's security policy, and hence it
2698   &SHOULD-NOT;  be transmitted without the user being able to disable,
2699   enable, and modify the contents of the field. The user &MUST; be able
2700   to set the contents of this field within a user preference or
2701   application defaults configuration.
2702</t>
2703<t>
2704   We suggest, though do not require, that a convenient toggle interface
2705   be provided for the user to enable or disable the sending of From and
2706   Referer information.
2707</t>
2708<t>
2709   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref target="header.server"/>) header
2710   fields can sometimes be used to determine that a specific client or
2711   server have a particular security hole which might be exploited.
2712   Unfortunately, this same information is often used for other valuable
2713   purposes for which HTTP currently has no better mechanism.
2714</t>
2715<t>
2716   Some methods, like TRACE (<xref target="TRACE"/>), expose information
2717   that was sent in request headers within the body of their response.
2718   Clients &SHOULD; be careful with sensitive information, like Cookies,
2719   Authorization credentials and other headers that might be used to
2720   collect data from the client.
2721</t> 
2722</section>
2723
2724<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2725<t>
2726   Because the source of a link might be private information or might
2727   reveal an otherwise private information source, it is strongly
2728   recommended that the user be able to select whether or not the
2729   Referer field is sent. For example, a browser client could have a
2730   toggle switch for browsing openly/anonymously, which would
2731   respectively enable/disable the sending of Referer and From
2732   information.
2733</t>
2734<t>
2735   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2736   HTTP request if the referring page was transferred with a secure
2737   protocol.
2738</t>
2739<t>
2740   Authors of services &SHOULD-NOT; use GET-based forms for the submission of
2741   sensitive data because that data will be placed in the request-target. Many
2742   existing servers, proxies, and user agents log or display the request-target
2743   in places where it might be visible to third parties. Such services can
2744   use POST-based form submission instead.
2745</t>
2746</section>
2747
2748<section title="Location Headers and Spoofing" anchor="location.spoofing">
2749<t>
2750   If a single server supports multiple organizations that do not trust
2751   one another, then it &MUST; check the values of Location and Content-Location
2752   headers in responses that are generated under control of
2753   said organizations to make sure that they do not attempt to
2754   invalidate resources over which they have no authority.
2755</t>
2756</section>
2757
2758</section>
2759
2760<section title="Acknowledgments" anchor="ack">
2761</section>
2762</middle>
2763<back>
2764
2765<references title="Normative References">
2766
2767<reference anchor="Part1">
2768  <front>
2769    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2770    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2771      <organization abbrev="Day Software">Day Software</organization>
2772      <address><email>fielding@gbiv.com</email></address>
2773    </author>
2774    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2775      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2776      <address><email>jg@freedesktop.org</email></address>
2777    </author>
2778    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2779      <organization abbrev="HP">Hewlett-Packard Company</organization>
2780      <address><email>JeffMogul@acm.org</email></address>
2781    </author>
2782    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2783      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2784      <address><email>henrikn@microsoft.com</email></address>
2785    </author>
2786    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2787      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2788      <address><email>LMM@acm.org</email></address>
2789    </author>
2790    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2791      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2792      <address><email>paulle@microsoft.com</email></address>
2793    </author>
2794    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2795      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2796      <address><email>timbl@w3.org</email></address>
2797    </author>
2798    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2799      <organization abbrev="W3C">World Wide Web Consortium</organization>
2800      <address><email>ylafon@w3.org</email></address>
2801    </author>
2802    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2803      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2804      <address><email>julian.reschke@greenbytes.de</email></address>
2805    </author>
2806    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2807  </front>
2808  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
2809  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
2810</reference>
2811
2812<reference anchor="Part3">
2813  <front>
2814    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
2815    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2816      <organization abbrev="Day Software">Day Software</organization>
2817      <address><email>fielding@gbiv.com</email></address>
2818    </author>
2819    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2820      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2821      <address><email>jg@freedesktop.org</email></address>
2822    </author>
2823    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2824      <organization abbrev="HP">Hewlett-Packard Company</organization>
2825      <address><email>JeffMogul@acm.org</email></address>
2826    </author>
2827    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2828      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2829      <address><email>henrikn@microsoft.com</email></address>
2830    </author>
2831    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2832      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2833      <address><email>LMM@acm.org</email></address>
2834    </author>
2835    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2836      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2837      <address><email>paulle@microsoft.com</email></address>
2838    </author>
2839    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2840      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2841      <address><email>timbl@w3.org</email></address>
2842    </author>
2843    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2844      <organization abbrev="W3C">World Wide Web Consortium</organization>
2845      <address><email>ylafon@w3.org</email></address>
2846    </author>
2847    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2848      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2849      <address><email>julian.reschke@greenbytes.de</email></address>
2850    </author>
2851    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2852  </front>
2853  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
2854  <x:source href="p3-payload.xml" basename="p3-payload"/>
2855</reference>
2856
2857<reference anchor="Part4">
2858  <front>
2859    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
2860    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2861      <organization abbrev="Day Software">Day Software</organization>
2862      <address><email>fielding@gbiv.com</email></address>
2863    </author>
2864    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2865      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2866      <address><email>jg@freedesktop.org</email></address>
2867    </author>
2868    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2869      <organization abbrev="HP">Hewlett-Packard Company</organization>
2870      <address><email>JeffMogul@acm.org</email></address>
2871    </author>
2872    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2873      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2874      <address><email>henrikn@microsoft.com</email></address>
2875    </author>
2876    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2877      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2878      <address><email>LMM@acm.org</email></address>
2879    </author>
2880    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2881      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2882      <address><email>paulle@microsoft.com</email></address>
2883    </author>
2884    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2885      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2886      <address><email>timbl@w3.org</email></address>
2887    </author>
2888    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2889      <organization abbrev="W3C">World Wide Web Consortium</organization>
2890      <address><email>ylafon@w3.org</email></address>
2891    </author>
2892    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2893      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2894      <address><email>julian.reschke@greenbytes.de</email></address>
2895    </author>
2896    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2897  </front>
2898  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
2899  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
2900</reference>
2901
2902<reference anchor="Part5">
2903  <front>
2904    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
2905    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2906      <organization abbrev="Day Software">Day Software</organization>
2907      <address><email>fielding@gbiv.com</email></address>
2908    </author>
2909    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2910      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2911      <address><email>jg@freedesktop.org</email></address>
2912    </author>
2913    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2914      <organization abbrev="HP">Hewlett-Packard Company</organization>
2915      <address><email>JeffMogul@acm.org</email></address>
2916    </author>
2917    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2918      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2919      <address><email>henrikn@microsoft.com</email></address>
2920    </author>
2921    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2922      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2923      <address><email>LMM@acm.org</email></address>
2924    </author>
2925    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2926      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2927      <address><email>paulle@microsoft.com</email></address>
2928    </author>
2929    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2930      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2931      <address><email>timbl@w3.org</email></address>
2932    </author>
2933    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2934      <organization abbrev="W3C">World Wide Web Consortium</organization>
2935      <address><email>ylafon@w3.org</email></address>
2936    </author>
2937    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2938      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2939      <address><email>julian.reschke@greenbytes.de</email></address>
2940    </author>
2941    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2942  </front>
2943  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
2944  <x:source href="p5-range.xml" basename="p5-range"/>
2945</reference>
2946
2947<reference anchor="Part6">
2948  <front>
2949    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
2950    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2951      <organization abbrev="Day Software">Day Software</organization>
2952      <address><email>fielding@gbiv.com</email></address>
2953    </author>
2954    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2955      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2956      <address><email>jg@freedesktop.org</email></address>
2957    </author>
2958    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2959      <organization abbrev="HP">Hewlett-Packard Company</organization>
2960      <address><email>JeffMogul@acm.org</email></address>
2961    </author>
2962    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2963      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2964      <address><email>henrikn@microsoft.com</email></address>
2965    </author>
2966    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2967      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2968      <address><email>LMM@acm.org</email></address>
2969    </author>
2970    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2971      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2972      <address><email>paulle@microsoft.com</email></address>
2973    </author>
2974    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2975      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2976      <address><email>timbl@w3.org</email></address>
2977    </author>
2978    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2979      <organization abbrev="W3C">World Wide Web Consortium</organization>
2980      <address><email>ylafon@w3.org</email></address>
2981    </author>
2982    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
2983      <address><email>mnot@mnot.net</email></address>
2984    </author>
2985    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2986      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2987      <address><email>julian.reschke@greenbytes.de</email></address>
2988    </author>
2989    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2990  </front>
2991  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
2992  <x:source href="p6-cache.xml" basename="p6-cache"/>
2993</reference>
2994
2995<reference anchor="Part7">
2996  <front>
2997    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
2998    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2999      <organization abbrev="Day Software">Day Software</organization>
3000      <address><email>fielding@gbiv.com</email></address>
3001    </author>
3002    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3003      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3004      <address><email>jg@freedesktop.org</email></address>
3005    </author>
3006    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3007      <organization abbrev="HP">Hewlett-Packard Company</organization>
3008      <address><email>JeffMogul@acm.org</email></address>
3009    </author>
3010    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3011      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3012      <address><email>henrikn@microsoft.com</email></address>
3013    </author>
3014    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3015      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3016      <address><email>LMM@acm.org</email></address>
3017    </author>
3018    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3019      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3020      <address><email>paulle@microsoft.com</email></address>
3021    </author>
3022    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3023      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3024      <address><email>timbl@w3.org</email></address>
3025    </author>
3026    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3027      <organization abbrev="W3C">World Wide Web Consortium</organization>
3028      <address><email>ylafon@w3.org</email></address>
3029    </author>
3030    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3031      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3032      <address><email>julian.reschke@greenbytes.de</email></address>
3033    </author>
3034    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3035  </front>
3036  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
3037  <x:source href="p7-auth.xml" basename="p7-auth"/>
3038</reference>
3039
3040<reference anchor="RFC2119">
3041  <front>
3042    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
3043    <author initials="S." surname="Bradner" fullname="Scott Bradner">
3044      <organization>Harvard University</organization>
3045      <address><email>sob@harvard.edu</email></address>
3046    </author>
3047    <date month="March" year="1997"/>
3048  </front>
3049  <seriesInfo name="BCP" value="14"/>
3050  <seriesInfo name="RFC" value="2119"/>
3051</reference>
3052
3053<reference anchor="RFC3986">
3054 <front>
3055  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
3056  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
3057    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3058    <address>
3059       <email>timbl@w3.org</email>
3060       <uri>http://www.w3.org/People/Berners-Lee/</uri>
3061    </address>
3062  </author>
3063  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
3064    <organization abbrev="Day Software">Day Software</organization>
3065    <address>
3066      <email>fielding@gbiv.com</email>
3067      <uri>http://roy.gbiv.com/</uri>
3068    </address>
3069  </author>
3070  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
3071    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
3072    <address>
3073      <email>LMM@acm.org</email>
3074      <uri>http://larry.masinter.net/</uri>
3075    </address>
3076  </author>
3077  <date month='January' year='2005'></date>
3078 </front>
3079 <seriesInfo name="RFC" value="3986"/>
3080 <seriesInfo name="STD" value="66"/>
3081</reference>
3082
3083<reference anchor="RFC5234">
3084  <front>
3085    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
3086    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3087      <organization>Brandenburg InternetWorking</organization>
3088      <address>
3089        <email>dcrocker@bbiw.net</email>
3090      </address> 
3091    </author>
3092    <author initials="P." surname="Overell" fullname="Paul Overell">
3093      <organization>THUS plc.</organization>
3094      <address>
3095        <email>paul.overell@thus.net</email>
3096      </address>
3097    </author>
3098    <date month="January" year="2008"/>
3099  </front>
3100  <seriesInfo name="STD" value="68"/>
3101  <seriesInfo name="RFC" value="5234"/>
3102</reference>
3103
3104</references>
3105
3106<references title="Informative References">
3107
3108<reference anchor="RFC1945">
3109  <front>
3110    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3111    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3112      <organization>MIT, Laboratory for Computer Science</organization>
3113      <address><email>timbl@w3.org</email></address>
3114    </author>
3115    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3116      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3117      <address><email>fielding@ics.uci.edu</email></address>
3118    </author>
3119    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3120      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3121      <address><email>frystyk@w3.org</email></address>
3122    </author>
3123    <date month="May" year="1996"/>
3124  </front>
3125  <seriesInfo name="RFC" value="1945"/>
3126</reference>
3127
3128<reference anchor="RFC2068">
3129  <front>
3130    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3131    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3132      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3133      <address><email>fielding@ics.uci.edu</email></address>
3134    </author>
3135    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3136      <organization>MIT Laboratory for Computer Science</organization>
3137      <address><email>jg@w3.org</email></address>
3138    </author>
3139    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3140      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3141      <address><email>mogul@wrl.dec.com</email></address>
3142    </author>
3143    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3144      <organization>MIT Laboratory for Computer Science</organization>
3145      <address><email>frystyk@w3.org</email></address>
3146    </author>
3147    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3148      <organization>MIT Laboratory for Computer Science</organization>
3149      <address><email>timbl@w3.org</email></address>
3150    </author>
3151    <date month="January" year="1997"/>
3152  </front>
3153  <seriesInfo name="RFC" value="2068"/>
3154</reference>
3155
3156<reference anchor="RFC2616">
3157  <front>
3158    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3159    <author initials="R." surname="Fielding" fullname="R. Fielding">
3160      <organization>University of California, Irvine</organization>
3161      <address><email>fielding@ics.uci.edu</email></address>
3162    </author>
3163    <author initials="J." surname="Gettys" fullname="J. Gettys">
3164      <organization>W3C</organization>
3165      <address><email>jg@w3.org</email></address>
3166    </author>
3167    <author initials="J." surname="Mogul" fullname="J. Mogul">
3168      <organization>Compaq Computer Corporation</organization>
3169      <address><email>mogul@wrl.dec.com</email></address>
3170    </author>
3171    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3172      <organization>MIT Laboratory for Computer Science</organization>
3173      <address><email>frystyk@w3.org</email></address>
3174    </author>
3175    <author initials="L." surname="Masinter" fullname="L. Masinter">
3176      <organization>Xerox Corporation</organization>
3177      <address><email>masinter@parc.xerox.com</email></address>
3178    </author>
3179    <author initials="P." surname="Leach" fullname="P. Leach">
3180      <organization>Microsoft Corporation</organization>
3181      <address><email>paulle@microsoft.com</email></address>
3182    </author>
3183    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3184      <organization>W3C</organization>
3185      <address><email>timbl@w3.org</email></address>
3186    </author>
3187    <date month="June" year="1999"/>
3188  </front>
3189  <seriesInfo name="RFC" value="2616"/>
3190</reference>
3191
3192<reference anchor='RFC2817'>
3193  <front>
3194    <title>Upgrading to TLS Within HTTP/1.1</title>
3195    <author initials='R.' surname='Khare' fullname='R. Khare'>
3196      <organization>4K Associates / UC Irvine</organization>
3197      <address><email>rohit@4K-associates.com</email></address>
3198    </author>
3199    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3200      <organization>Agranat Systems, Inc.</organization>
3201      <address><email>lawrence@agranat.com</email></address>
3202    </author>
3203    <date year='2000' month='May' />
3204  </front>
3205  <seriesInfo name='RFC' value='2817' />
3206</reference>
3207
3208<reference anchor='RFC3864'>
3209  <front>
3210    <title>Registration Procedures for Message Header Fields</title>
3211    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3212      <organization>Nine by Nine</organization>
3213      <address><email>GK-IETF@ninebynine.org</email></address>
3214    </author>
3215    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3216      <organization>BEA Systems</organization>
3217      <address><email>mnot@pobox.com</email></address>
3218    </author>
3219    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3220      <organization>HP Labs</organization>
3221      <address><email>JeffMogul@acm.org</email></address>
3222    </author>
3223    <date year='2004' month='September' />
3224  </front>
3225  <seriesInfo name='BCP' value='90' />
3226  <seriesInfo name='RFC' value='3864' />
3227</reference>
3228
3229<reference anchor='RFC5226'>
3230  <front>
3231    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3232    <author initials='T.' surname='Narten' fullname='T. Narten'>
3233      <organization>IBM</organization>
3234      <address><email>narten@us.ibm.com</email></address>
3235    </author>
3236    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3237      <organization>Google</organization>
3238      <address><email>Harald@Alvestrand.no</email></address>
3239    </author>
3240    <date year='2008' month='May' />
3241  </front>
3242  <seriesInfo name='BCP' value='26' />
3243  <seriesInfo name='RFC' value='5226' />
3244</reference>
3245
3246<reference anchor="RFC5322">
3247  <front>
3248    <title>Internet Message Format</title>
3249    <author initials="P." surname="Resnick" fullname="P. Resnick">
3250      <organization>Qualcomm Incorporated</organization>
3251    </author>
3252    <date year="2008" month="October"/>
3253  </front> 
3254  <seriesInfo name="RFC" value="5322"/>
3255</reference>
3256
3257</references>
3258
3259<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3260<t>
3261  This document takes over the Status Code Registry, previously defined
3262  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3263  (<xref target="status.code.registry"/>)
3264</t>
3265<t>
3266  Clarify definition of POST.
3267  (<xref target="POST"/>)
3268</t>
3269<t>
3270  Failed to consider that there are
3271  many other request methods that are safe to automatically redirect,
3272  and further that the user agent is able to make that determination
3273  based on the request method semantics.
3274  (Sections <xref format="counter" target="status.301"/>,
3275  <xref format="counter" target="status.302"/> and
3276  <xref format="counter" target="status.307"/>)
3277</t>
3278<t>
3279  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3280  It used to indicate that the target resource must be accessed through the
3281  proxy given by the Location field. The Location field gave the URI of the
3282  proxy. The recipient was expected to repeat this single request via the proxy.
3283  (<xref target="status.305"/>)
3284</t>
3285<t>
3286  Reclassify Allow header as response header, removing the option to
3287  specify it in a PUT request.
3288  Relax the server requirement on the contents of the Allow header and
3289  remove requirement on clients to always trust the header value.
3290  (<xref target="header.allow"/>)
3291</t>
3292<t>
3293  Correct syntax of Location header to allow URI references (including
3294  relative references and fragments), as referred symbol "absoluteURI" wasn't
3295  what was expected, and add some clarifications as to when use of fragments
3296  would not be appropriate.
3297  (<xref target="header.location"/>)
3298</t>
3299<t>
3300  Allow Referer value of "about:blank" as alternative to not specifying it.
3301  (<xref target="header.referer"/>)
3302</t>
3303<t>
3304  In the description of the Server header, the Via field
3305  was described as a SHOULD. The requirement was and is stated
3306  correctly in the description of the Via header in &header-via;.
3307  (<xref target="header.server"/>)
3308</t>
3309</section>
3310
3311<?BEGININC p2-semantics.abnf-appendix ?>
3312<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3313<figure>
3314<artwork type="abnf" name="p2-semantics.parsed-abnf">
3315<x:ref>Accept</x:ref> = &lt;Accept, defined in [Part3], Section 6.1&gt;
3316<x:ref>Accept-Charset</x:ref> = &lt;Accept-Charset, defined in [Part3], Section 6.2&gt;
3317<x:ref>Accept-Encoding</x:ref> = &lt;Accept-Encoding, defined in [Part3], Section 6.3&gt;
3318<x:ref>Accept-Language</x:ref> = &lt;Accept-Language, defined in [Part3], Section 6.4&gt;
3319<x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in [Part5], Section 5.1&gt;
3320<x:ref>Age</x:ref> = &lt;Age, defined in [Part6], Section 3.1&gt;
3321<x:ref>Allow</x:ref> = "Allow:" OWS Allow-v
3322<x:ref>Allow-v</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3323<x:ref>Authorization</x:ref> = &lt;Authorization, defined in [Part7], Section 3.1&gt;
3324
3325<x:ref>ETag</x:ref> = &lt;ETag, defined in [Part4], Section 6.1&gt;
3326<x:ref>Expect</x:ref> = "Expect:" OWS Expect-v
3327<x:ref>Expect-v</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3328
3329<x:ref>From</x:ref> = "From:" OWS From-v
3330<x:ref>From-v</x:ref> = mailbox
3331
3332<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3333<x:ref>Host</x:ref> = &lt;Host, defined in [Part1], Section 2.6&gt;
3334
3335<x:ref>If-Match</x:ref> = &lt;If-Match, defined in [Part4], Section 6.2&gt;
3336If-Modified-Since =
3337 &lt;If-Modified-Since, defined in [Part4], Section 6.3&gt;
3338<x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in [Part4], Section 6.4&gt;
3339<x:ref>If-Range</x:ref> = &lt;If-Range, defined in [Part5], Section 5.3&gt;
3340If-Unmodified-Since =
3341 &lt;If-Unmodified-Since, defined in [Part4], Section 6.5&gt;
3342
3343<x:ref>Location</x:ref> = "Location:" OWS Location-v
3344<x:ref>Location-v</x:ref> = URI-reference
3345
3346<x:ref>Max-Forwards</x:ref> = "Max-Forwards:" OWS Max-Forwards-v
3347<x:ref>Max-Forwards-v</x:ref> = 1*DIGIT
3348<x:ref>Method</x:ref> = %x4F.50.54.49.4F.4E.53 ; OPTIONS
3349 / %x47.45.54 ; GET
3350 / %x48.45.41.44 ; HEAD
3351 / %x50.4F.53.54 ; POST
3352 / %x50.55.54 ; PUT
3353 / %x44.45.4C.45.54.45 ; DELETE
3354 / %x54.52.41.43.45 ; TRACE
3355 / %x43.4F.4E.4E.45.43.54 ; CONNECT
3356 / extension-method
3357
3358<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3359
3360Proxy-Authenticate =
3361 &lt;Proxy-Authenticate, defined in [Part7], Section 3.2&gt;
3362Proxy-Authorization =
3363 &lt;Proxy-Authorization, defined in [Part7], Section 3.3&gt;
3364
3365<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3366<x:ref>Range</x:ref> = &lt;Range, defined in [Part5], Section 5.4&gt;
3367<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3368<x:ref>Referer</x:ref> = "Referer:" OWS Referer-v
3369<x:ref>Referer-v</x:ref> = absolute-URI / partial-URI
3370<x:ref>Retry-After</x:ref> = "Retry-After:" OWS Retry-After-v
3371<x:ref>Retry-After-v</x:ref> = HTTP-date / delta-seconds
3372
3373<x:ref>Server</x:ref> = "Server:" OWS Server-v
3374<x:ref>Server-v</x:ref> = product *( RWS ( product / comment ) )
3375<x:ref>Status-Code</x:ref> = "100" / "101" / "200" / "201" / "202" / "203" / "204" /
3376 "205" / "206" / "300" / "301" / "302" / "303" / "304" / "305" /
3377 "307" / "400" / "401" / "402" / "403" / "404" / "405" / "406" /
3378 "407" / "408" / "409" / "410" / "411" / "412" / "413" / "414" /
3379 "415" / "416" / "417" / "500" / "501" / "502" / "503" / "504" /
3380 "505" / extension-code
3381
3382<x:ref>TE</x:ref> = &lt;TE, defined in [Part1], Section 9.5&gt;
3383
3384<x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in [Part1], Section 2.6&gt;
3385<x:ref>User-Agent</x:ref> = "User-Agent:" OWS User-Agent-v
3386<x:ref>User-Agent-v</x:ref> = product *( RWS ( product / comment ) )
3387
3388<x:ref>Vary</x:ref> = &lt;Vary, defined in [Part6], Section 3.5&gt;
3389
3390WWW-Authenticate =
3391 &lt;WWW-Authenticate, defined in [Part7], Section 3.4&gt;
3392
3393<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
3394
3395<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3396
3397<x:ref>delta-seconds</x:ref> = 1*DIGIT
3398
3399<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3400<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3401<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3402 *expect-params ]
3403<x:ref>extension-code</x:ref> = 3DIGIT
3404<x:ref>extension-method</x:ref> = token
3405
3406<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3407
3408<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3409
3410<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
3411<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3412
3413<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3414
3415<x:ref>request-header</x:ref> = Accept / Accept-Charset / Accept-Encoding /
3416 Accept-Language / Authorization / Expect / From / Host / If-Match /
3417 If-Modified-Since / If-None-Match / If-Range / If-Unmodified-Since /
3418 Max-Forwards / Proxy-Authorization / Range / Referer / TE /
3419 User-Agent
3420<x:ref>response-header</x:ref> = Accept-Ranges / Age / Allow / ETag / Location /
3421 Proxy-Authenticate / Retry-After / Server / Vary / WWW-Authenticate
3422
3423<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3424</artwork>
3425</figure>
3426<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3427; Reason-Phrase defined but not used
3428; Status-Code defined but not used
3429; request-header defined but not used
3430; response-header defined but not used
3431</artwork></figure></section>
3432<?ENDINC p2-semantics.abnf-appendix ?>
3433
3434<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3435
3436<section title="Since RFC2616">
3437<t>
3438  Extracted relevant partitions from <xref target="RFC2616"/>.
3439</t>
3440</section>
3441
3442<section title="Since draft-ietf-httpbis-p2-semantics-00">
3443<t>
3444  Closed issues:
3445  <list style="symbols"> 
3446    <t>
3447      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3448      "Via is a MUST"
3449      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3450    </t>
3451    <t>
3452      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3453      "Fragments allowed in Location"
3454      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3455    </t>
3456    <t>
3457      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3458      "Safe Methods vs Redirection"
3459      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3460    </t>
3461    <t>
3462      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3463      "Revise description of the POST method"
3464      (<eref target="http://purl.org/NET/http-errata#post"/>)
3465    </t>
3466    <t>
3467      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3468      "Normative and Informative references"
3469    </t>
3470    <t>
3471      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3472      "RFC2606 Compliance"
3473    </t>
3474    <t>
3475      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3476      "Informative references"
3477    </t>
3478    <t>
3479      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3480      "Redundant cross-references"
3481    </t>
3482  </list>
3483</t>
3484<t>
3485  Other changes:
3486  <list style="symbols"> 
3487    <t>
3488      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3489    </t>
3490  </list>
3491</t>
3492</section>
3493
3494<section title="Since draft-ietf-httpbis-p2-semantics-01">
3495<t>
3496  Closed issues:
3497  <list style="symbols"> 
3498    <t>
3499      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3500      "PUT side effects"
3501    </t>
3502    <t>
3503      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3504      "Duplicate Host header requirements"
3505    </t>
3506  </list>
3507</t>
3508<t>
3509  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3510  <list style="symbols"> 
3511    <t>
3512      Move "Product Tokens" section (back) into Part 1, as "token" is used
3513      in the definition of the Upgrade header.
3514    </t>
3515    <t>
3516      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3517    </t>
3518    <t>
3519      Copy definition of delta-seconds from Part6 instead of referencing it.
3520    </t>
3521  </list>
3522</t>
3523</section>
3524
3525<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3526<t>
3527  Closed issues:
3528  <list style="symbols"> 
3529    <t>
3530      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3531      "Requiring Allow in 405 responses"
3532    </t>
3533    <t>
3534      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3535      "Status Code Registry"
3536    </t>
3537    <t>
3538      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3539      "Redirection vs. Location"
3540    </t>
3541    <t>
3542      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3543      "Cacheability of 303 response"
3544    </t>
3545    <t>
3546      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3547      "305 Use Proxy"
3548    </t>
3549    <t>
3550      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3551      "Classification for Allow header"
3552    </t>
3553    <t>
3554      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3555      "PUT - 'store under' vs 'store at'"
3556    </t>
3557  </list>
3558</t>
3559<t>
3560  Ongoing work on IANA Message Header Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3561  <list style="symbols"> 
3562    <t>
3563      Reference RFC 3984, and update header registrations for headers defined
3564      in this document.
3565    </t>
3566  </list>
3567</t>
3568<t>
3569  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3570  <list style="symbols"> 
3571    <t>
3572      Replace string literals when the string really is case-sensitive (method).
3573    </t>
3574  </list>
3575</t>
3576</section>
3577
3578<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3579<t>
3580  Closed issues:
3581  <list style="symbols"> 
3582    <t>
3583      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3584      "OPTIONS request bodies"
3585    </t>
3586    <t>
3587      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3588      "Description of CONNECT should refer to RFC2817"
3589    </t>
3590    <t>
3591      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3592      "Location Content-Location reference request/response mixup"
3593    </t>
3594  </list>
3595</t>
3596<t>
3597  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3598  <list style="symbols"> 
3599    <t>
3600      Added initial proposal for registration process, plus initial
3601      content (non-HTTP/1.1 methods to be added by a separate specification).
3602    </t>
3603  </list>
3604</t>
3605</section>
3606
3607<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3608<t>
3609  Closed issues:
3610  <list style="symbols"> 
3611    <t>
3612      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3613      "Content-*"
3614    </t>
3615    <t>
3616      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3617      "RFC 2822 is updated by RFC 5322"
3618    </t>
3619  </list>
3620</t>
3621<t>
3622  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3623  <list style="symbols"> 
3624    <t>
3625      Use "/" instead of "|" for alternatives.
3626    </t>
3627    <t>
3628      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3629      whitespace ("OWS") and required whitespace ("RWS").
3630    </t>
3631    <t>
3632      Rewrite ABNFs to spell out whitespace rules, factor out
3633      header value format definitions.
3634    </t>
3635  </list>
3636</t>
3637</section>
3638
3639<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3640<t>
3641  Closed issues:
3642  <list style="symbols"> 
3643    <t>
3644      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3645      "Reason-Phrase BNF"
3646    </t>
3647  </list>
3648</t>
3649<t>
3650  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3651  <list style="symbols"> 
3652    <t>
3653      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3654    </t>
3655  </list>
3656</t>
3657</section>
3658
3659<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3660<t>
3661  Closed issues:
3662  <list style="symbols"> 
3663    <t>
3664      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3665      "Clarify when Referer is sent"
3666    </t>
3667    <t>
3668      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3669      "status codes vs methods"
3670    </t>
3671    <t>
3672      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3673      "Do not require "updates" relation for specs that register status codes or method names"
3674    </t>
3675  </list>
3676</t>
3677</section>
3678
3679<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3680<t>
3681  Closed issues:
3682  <list style="symbols"> 
3683    <t>
3684      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3685      "Idempotency"
3686    </t>
3687    <t>
3688      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3689      "TRACE security considerations"
3690    </t>
3691    <t>
3692      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3693      "Clarify rules for determining what entities a response carries"
3694    </t>
3695    <t>
3696      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3697      "update note citing RFC 1945 and 2068"
3698    </t>
3699    <t>
3700      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3701      "update note about redirect limit"
3702    </t>
3703    <t>
3704      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3705      "Location header ABNF should use 'URI'"
3706    </t>
3707    <t>
3708      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3709      "fragments in Location vs status 303"
3710    </t>
3711    <t>
3712      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
3713      "move IANA registrations for optional status codes"
3714    </t>
3715  </list>
3716</t>
3717<t>
3718  Partly resolved issues:
3719  <list style="symbols"> 
3720    <t>
3721      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/171"/>:
3722      "Are OPTIONS and TRACE safe?"
3723    </t>
3724  </list>
3725</t>
3726</section>
3727
3728<section title="Since draft-ietf-httpbis-p2-semantics-08" anchor="changes.since.08">
3729<t>
3730  Closed issues:
3731  <list style="symbols"> 
3732    <t>
3733      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3734      "Safe Methods vs Redirection" (we missed the introduction to the 3xx
3735      status codes when fixing this previously)
3736    </t>
3737  </list>
3738</t>
3739</section>
3740
3741<section title="Since draft-ietf-httpbis-p2-semantics-09" anchor="changes.since.09">
3742<t>
3743  Closed issues:
3744  <list style="symbols"> 
3745    <t>
3746      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
3747      "Fragment combination / precedence during redirects"
3748    </t>
3749  </list>
3750</t>
3751<t>
3752  Partly resolved issues:
3753  <list style="symbols"> 
3754    <t>
3755      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/185"/>:
3756      "Location header payload handling"
3757    </t>
3758    <t>
3759      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
3760      "Term for the requested resource's URI"
3761    </t>
3762  </list>
3763</t>
3764</section>
3765
3766<section title="Since draft-ietf-httpbis-p2-semantics-10" anchor="changes.since.10">
3767<t>
3768  Closed issues:
3769  <list style="symbols"> 
3770    <t>
3771      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
3772      "Clarify 'Requested Variant'"
3773    </t>
3774    <t>
3775      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
3776      "Clarify entity / representation / variant terminology"
3777    </t>
3778    <t>
3779      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/139"/>:
3780      "Methods and Caching"
3781    </t>
3782    <t>
3783      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/190"/>:
3784      "OPTIONS vs Max-Forwards"
3785    </t>
3786    <t>
3787      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/199"/>:
3788      "Status codes and caching"
3789    </t>
3790    <t>
3791      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
3792      "consider removing the 'changes from 2068' sections"
3793    </t>
3794  </list>
3795</t>
3796</section>
3797
3798</section>
3799
3800</back>
3801</rfc>
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