source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1050

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1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "October">
16  <!ENTITY ID-YEAR "2010">
17  <!ENTITY notation                   "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
18  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY payload                    "<xref target='Part3' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY conditional                "<xref target='Part4' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY range                      "<xref target='Part5' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY caching                    "<xref target='Part6' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY auth                       "<xref target='Part7' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY combining-responses        "<xref target='Part6' x:rel='#combining.responses' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY content-negotiation        "<xref target='Part3' x:rel='#content.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY notation-abnf              "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY basic-rules                "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY uri                        "<xref target='Part1' x:rel='#uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY effective-request-uri      "<xref target='Part1' x:rel='#effective.request.uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY full-date                  "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY http-url                   "<xref target='Part1' x:rel='#http-url' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY http-version               "<xref target='Part1' x:rel='#http.version' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY use100                     "<xref target='Part1' x:rel='#use.of.the.100.status' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY qvalue                     "<xref target='Part3' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35  <!ENTITY header-accept              "<xref target='Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY header-accept-charset      "<xref target='Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY header-accept-encoding     "<xref target='Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY header-accept-language     "<xref target='Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY header-accept-ranges       "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY header-age                 "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41  <!ENTITY header-authorization       "<xref target='Part7' x:rel='#header.authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
42  <!ENTITY header-cache-control       "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
43  <!ENTITY header-content-location    "<xref target='Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
44  <!ENTITY header-content-range       "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
45  <!ENTITY header-etag                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
46  <!ENTITY header-expires             "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
47  <!ENTITY header-fields              "<xref target='Part1' x:rel='#header.fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
48  <!ENTITY header-host                "<xref target='Part1' x:rel='#header.host' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
49  <!ENTITY header-if-match            "<xref target='Part4' x:rel='#header.if-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
50  <!ENTITY header-if-modified-since   "<xref target='Part4' x:rel='#header.if-modified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
51  <!ENTITY header-if-none-match       "<xref target='Part4' x:rel='#header.if-none-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
52  <!ENTITY header-if-range            "<xref target='Part5' x:rel='#header.if-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
53  <!ENTITY header-if-unmodified-since "<xref target='Part4' x:rel='#header.if-unmodified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
54  <!ENTITY header-pragma              "<xref target='Part6' x:rel='#header.pragma' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
55  <!ENTITY header-proxy-authenticate  "<xref target='Part7' x:rel='#header.proxy-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
56  <!ENTITY header-proxy-authorization "<xref target='Part7' x:rel='#header.proxy-authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
57  <!ENTITY header-range               "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
58  <!ENTITY header-upgrade             "<xref target='Part1' x:rel='#header.upgrade' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
59  <!ENTITY header-te                  "<xref target='Part1' x:rel='#header.te' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
60  <!ENTITY header-vary                "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
61  <!ENTITY header-via                 "<xref target='Part1' x:rel='#header.via' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
62  <!ENTITY header-warning             "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
63  <!ENTITY header-www-authenticate    "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
64  <!ENTITY message-body               "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
65  <!ENTITY product-tokens             "<xref target='Part1' x:rel='#product.tokens' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
66  <!ENTITY media-type-message-http    "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
67  <!ENTITY status-206                 "<xref target='Part5' x:rel='#status.206' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
68  <!ENTITY status-304                 "<xref target='Part4' x:rel='#status.304' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
69  <!ENTITY status-401                 "<xref target='Part7' x:rel='#status.401' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
70  <!ENTITY status-407                 "<xref target='Part7' x:rel='#status.407' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
71  <!ENTITY status-412                 "<xref target='Part4' x:rel='#status.412' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
72  <!ENTITY status-416                 "<xref target='Part5' x:rel='#status.416' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
73  <!ENTITY p4-status-codes            "<xref target='Part4' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
74  <!ENTITY p5-status-codes            "<xref target='Part5' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
75  <!ENTITY p7-status-codes            "<xref target='Part7' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
76  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
77  <!ENTITY p6-explicit               "<xref target='Part6' x:rel='#calculating.freshness.lifetime' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
78]>
79<?rfc toc="yes" ?>
80<?rfc symrefs="yes" ?>
81<?rfc sortrefs="yes" ?>
82<?rfc compact="yes"?>
83<?rfc subcompact="no" ?>
84<?rfc linkmailto="no" ?>
85<?rfc editing="no" ?>
86<?rfc comments="yes"?>
87<?rfc inline="yes"?>
88<?rfc rfcedstyle="yes"?>
89<?rfc-ext allow-markup-in-artwork="yes" ?>
90<?rfc-ext include-references-in-index="yes" ?>
91<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
92     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
93     xmlns:x='http://purl.org/net/xml2rfc/ext'
94     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
95<front>
96
97  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
98
99  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
100    <organization abbrev="Day Software">Day Software</organization>
101    <address>
102      <postal>
103        <street>23 Corporate Plaza DR, Suite 280</street>
104        <city>Newport Beach</city>
105        <region>CA</region>
106        <code>92660</code>
107        <country>USA</country>
108      </postal>
109      <phone>+1-949-706-5300</phone>
110      <facsimile>+1-949-706-5305</facsimile>
111      <email>fielding@gbiv.com</email>
112      <uri>http://roy.gbiv.com/</uri>
113    </address>
114  </author>
115
116  <author initials="J." surname="Gettys" fullname="Jim Gettys">
117    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
118    <address>
119      <postal>
120        <street>21 Oak Knoll Road</street>
121        <city>Carlisle</city>
122        <region>MA</region>
123        <code>01741</code>
124        <country>USA</country>
125      </postal>
126      <email>jg@freedesktop.org</email>
127      <uri>http://gettys.wordpress.com/</uri>
128    </address>
129  </author>
130 
131  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
132    <organization abbrev="HP">Hewlett-Packard Company</organization>
133    <address>
134      <postal>
135        <street>HP Labs, Large Scale Systems Group</street>
136        <street>1501 Page Mill Road, MS 1177</street>
137        <city>Palo Alto</city>
138        <region>CA</region>
139        <code>94304</code>
140        <country>USA</country>
141      </postal>
142      <email>JeffMogul@acm.org</email>
143    </address>
144  </author>
145
146  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
147    <organization abbrev="Microsoft">Microsoft Corporation</organization>
148    <address>
149      <postal>
150        <street>1 Microsoft Way</street>
151        <city>Redmond</city>
152        <region>WA</region>
153        <code>98052</code>
154        <country>USA</country>
155      </postal>
156      <email>henrikn@microsoft.com</email>
157    </address>
158  </author>
159
160  <author initials="L." surname="Masinter" fullname="Larry Masinter">
161    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
162    <address>
163      <postal>
164        <street>345 Park Ave</street>
165        <city>San Jose</city>
166        <region>CA</region>
167        <code>95110</code>
168        <country>USA</country>
169      </postal>
170      <email>LMM@acm.org</email>
171      <uri>http://larry.masinter.net/</uri>
172    </address>
173  </author>
174 
175  <author initials="P." surname="Leach" fullname="Paul J. Leach">
176    <organization abbrev="Microsoft">Microsoft Corporation</organization>
177    <address>
178      <postal>
179        <street>1 Microsoft Way</street>
180        <city>Redmond</city>
181        <region>WA</region>
182        <code>98052</code>
183      </postal>
184      <email>paulle@microsoft.com</email>
185    </address>
186  </author>
187   
188  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
189    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
190    <address>
191      <postal>
192        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
193        <street>The Stata Center, Building 32</street>
194        <street>32 Vassar Street</street>
195        <city>Cambridge</city>
196        <region>MA</region>
197        <code>02139</code>
198        <country>USA</country>
199      </postal>
200      <email>timbl@w3.org</email>
201      <uri>http://www.w3.org/People/Berners-Lee/</uri>
202    </address>
203  </author>
204
205  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
206    <organization abbrev="W3C">World Wide Web Consortium</organization>
207    <address>
208      <postal>
209        <street>W3C / ERCIM</street>
210        <street>2004, rte des Lucioles</street>
211        <city>Sophia-Antipolis</city>
212        <region>AM</region>
213        <code>06902</code>
214        <country>France</country>
215      </postal>
216      <email>ylafon@w3.org</email>
217      <uri>http://www.raubacapeu.net/people/yves/</uri>
218    </address>
219  </author>
220
221  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
222    <organization abbrev="greenbytes">greenbytes GmbH</organization>
223    <address>
224      <postal>
225        <street>Hafenweg 16</street>
226        <city>Muenster</city><region>NW</region><code>48155</code>
227        <country>Germany</country>
228      </postal>
229      <phone>+49 251 2807760</phone>
230      <facsimile>+49 251 2807761</facsimile>
231      <email>julian.reschke@greenbytes.de</email>
232      <uri>http://greenbytes.de/tech/webdav/</uri>
233    </address>
234  </author>
235
236  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
237  <workgroup>HTTPbis Working Group</workgroup>
238
239<abstract>
240<t>
241   The Hypertext Transfer Protocol (HTTP) is an application-level
242   protocol for distributed, collaborative, hypermedia information
243   systems. HTTP has been in use by the World Wide Web global information
244   initiative since 1990. This document is Part 2 of the seven-part specification
245   that defines the protocol referred to as "HTTP/1.1" and, taken together,
246   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
247   as expressed by request methods, request-header fields, response status codes,
248   and response-header fields.
249</t>
250</abstract>
251
252<note title="Editorial Note (To be removed by RFC Editor)">
253  <t>
254    Discussion of this draft should take place on the HTTPBIS working group
255    mailing list (ietf-http-wg@w3.org). The current issues list is
256    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/>
257    and related documents (including fancy diffs) can be found at
258    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
259  </t>
260  <t>
261    The changes in this draft are summarized in <xref target="changes.since.11"/>.
262  </t>
263</note>
264</front>
265<middle>
266<section title="Introduction" anchor="introduction">
267<t>
268   This document defines HTTP/1.1 request and response semantics.  Each HTTP
269   message, as defined in &messaging;, is in the form of either a request or
270   a response.  An HTTP server listens on a connection for HTTP requests and
271   responds to each request, in the order received on that connection, with
272   one or more HTTP response messages.  This document defines the commonly
273   agreed upon semantics of the HTTP uniform interface, the intentions defined
274   by each request method, and the various response messages that might be
275   expected as a result of applying that method to the target resource.
276</t>
277<t>
278   This document is currently disorganized in order to minimize the changes
279   between drafts and enable reviewers to see the smaller errata changes.
280   A future draft will reorganize the sections to better reflect the content.
281   In particular, the sections will be ordered according to the typical
282   processing of an HTTP request message (after message parsing): resource
283   mapping, general header fields, methods, request modifiers, response
284   status, and resource metadata.  The current mess reflects how widely
285   dispersed these topics and associated requirements had become in
286   <xref target="RFC2616"/>.
287</t>
288
289<section title="Requirements" anchor="intro.requirements">
290<t>
291   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
292   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
293   document are to be interpreted as described in <xref target="RFC2119"/>.
294</t>
295<t>
296   An implementation is not compliant if it fails to satisfy one or more
297   of the "MUST" or "REQUIRED" level requirements for the protocols it
298   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
299   level and all the "SHOULD" level requirements for its protocols is said
300   to be "unconditionally compliant"; one that satisfies all the "MUST"
301   level requirements but not all the "SHOULD" level requirements for its
302   protocols is said to be "conditionally compliant".
303</t>
304</section>
305
306<section title="Syntax Notation" anchor="notation">
307  <x:anchor-alias value="CR"/>
308  <x:anchor-alias value="DIGIT"/>
309  <x:anchor-alias value="LF"/>
310  <x:anchor-alias value="VCHAR"/>
311  <x:anchor-alias value="WSP"/>
312<t>
313  This specification uses the ABNF syntax defined in &notation; (which
314  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
315  <xref target="collected.abnf"/> shows the collected ABNF, with the list
316  rule expanded.
317</t>
318<t>
319  The following core rules are included by
320  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
321  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
322  DIGIT (decimal 0-9), DQUOTE (double quote),
323  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
324  OCTET (any 8-bit sequence of data), SP (space),
325  VCHAR (any visible USASCII character),
326  and WSP (whitespace).
327</t>
328
329<section title="Core Rules" anchor="core.rules">
330  <x:anchor-alias value="obs-text"/>
331  <x:anchor-alias value="quoted-string"/>
332  <x:anchor-alias value="token"/>
333  <x:anchor-alias value="OWS"/>
334  <x:anchor-alias value="RWS"/>
335<t>
336  The core rules below are defined in &basic-rules;:
337</t>
338<figure><artwork type="abnf2616">
339  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
340  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
341  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
342  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
343  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
344</artwork></figure>
345</section>
346
347<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
348  <x:anchor-alias value="absolute-URI"/>
349  <x:anchor-alias value="Accept"/>
350  <x:anchor-alias value="Accept-Charset"/>
351  <x:anchor-alias value="Accept-Encoding"/>
352  <x:anchor-alias value="Accept-Language"/>
353  <x:anchor-alias value="Accept-Ranges"/>
354  <x:anchor-alias value="Age"/>
355  <x:anchor-alias value="Authorization"/>
356  <x:anchor-alias value="comment"/>
357  <x:anchor-alias value="ETag"/>
358  <x:anchor-alias value="Host"/>
359  <x:anchor-alias value="HTTP-date"/>
360  <x:anchor-alias value="If-Match"/>
361  <x:anchor-alias value="If-Modified-Since"/>
362  <x:anchor-alias value="If-None-Match"/>
363  <x:anchor-alias value="If-Range"/>
364  <x:anchor-alias value="If-Unmodified-Since"/>
365  <x:anchor-alias value="partial-URI"/>
366  <x:anchor-alias value="product"/>
367  <x:anchor-alias value="Proxy-Authenticate"/>
368  <x:anchor-alias value="Proxy-Authorization"/>
369  <x:anchor-alias value="Range"/>
370  <x:anchor-alias value="TE"/>
371  <x:anchor-alias value="URI-reference"/>
372  <x:anchor-alias value="Vary"/>
373  <x:anchor-alias value="WWW-Authenticate"/>
374<t>
375  The ABNF rules below are defined in other parts:
376</t>
377<figure><!--Part1--><artwork type="abnf2616">
378  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
379  <x:ref>comment</x:ref>       = &lt;comment, defined in &header-fields;&gt;
380  <x:ref>Host</x:ref>          = &lt;Host, defined in &uri;&gt;
381  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
382  <x:ref>partial-URI</x:ref>   = &lt;partial-URI, defined in &uri;&gt;
383  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
384  <x:ref>TE</x:ref>            = &lt;TE, defined in &header-te;&gt;
385  <x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in &uri;&gt;
386</artwork></figure>
387<figure><!--Part3--><artwork type="abnf2616">
388  <x:ref>Accept</x:ref>        = &lt;Accept, defined in &header-accept;&gt;
389  <x:ref>Accept-Charset</x:ref> =
390             &lt;Accept-Charset, defined in &header-accept-charset;&gt;
391  <x:ref>Accept-Encoding</x:ref> =
392             &lt;Accept-Encoding, defined in &header-accept-encoding;&gt;
393  <x:ref>Accept-Language</x:ref> =
394             &lt;Accept-Language, defined in &header-accept-language;&gt;
395</artwork></figure>
396<figure><!--Part4--><artwork type="abnf2616">
397  <x:ref>ETag</x:ref>          = &lt;ETag, defined in &header-etag;&gt;
398  <x:ref>If-Match</x:ref>      = &lt;If-Match, defined in &header-if-match;&gt;
399  <x:ref>If-Modified-Since</x:ref> =
400             &lt;If-Modified-Since, defined in &header-if-modified-since;&gt;
401  <x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in &header-if-none-match;&gt;
402  <x:ref>If-Unmodified-Since</x:ref> =
403             &lt;If-Unmodified-Since, defined in &header-if-unmodified-since;&gt;
404</artwork></figure>
405<figure><!--Part5--><artwork type="abnf2616">
406  <x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in &header-accept-ranges;&gt;
407  <x:ref>If-Range</x:ref>      = &lt;If-Range, defined in &header-if-range;&gt;
408  <x:ref>Range</x:ref>         = &lt;Range, defined in &header-range;&gt;
409</artwork></figure>
410<figure><!--Part6--><artwork type="abnf2616">
411  <x:ref>Age</x:ref>           = &lt;Age, defined in &header-age;&gt;
412  <x:ref>Vary</x:ref>          = &lt;Vary, defined in &header-vary;&gt;
413</artwork><!--Part7--></figure>
414<figure><artwork type="abnf2616">
415  <x:ref>Authorization</x:ref> = &lt;Authorization, defined in &header-authorization;&gt;
416  <x:ref>Proxy-Authenticate</x:ref> =
417             &lt;Proxy-Authenticate, defined in &header-proxy-authenticate;&gt;
418  <x:ref>Proxy-Authorization</x:ref> =
419             &lt;Proxy-Authorization, defined in &header-proxy-authorization;&gt;
420  <x:ref>WWW-Authenticate</x:ref> =
421             &lt;WWW-Authenticate, defined in &header-www-authenticate;&gt;
422</artwork></figure>
423</section>
424</section>
425</section>
426
427<section title="Method" anchor="method">
428  <x:anchor-alias value="Method"/>
429  <x:anchor-alias value="extension-method"/>
430<t>
431   The Method token indicates the method to be performed on the target
432   resource (&effective-request-uri;). The method is case-sensitive.
433</t>
434<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/><iref primary="true" item="Grammar" subitem="extension-method"/>
435  <x:ref>Method</x:ref>         = <x:abnf-char-sequence>"OPTIONS"</x:abnf-char-sequence>   ; "OPTIONS", <xref target="OPTIONS"/>
436                 / <x:abnf-char-sequence>"GET"</x:abnf-char-sequence>               ; "GET", <xref target="GET"/>
437                 / <x:abnf-char-sequence>"HEAD"</x:abnf-char-sequence>            ; "HEAD", <xref target="HEAD"/>
438                 / <x:abnf-char-sequence>"POST"</x:abnf-char-sequence>            ; "POST", <xref target="POST"/>
439                 / <x:abnf-char-sequence>"PUT"</x:abnf-char-sequence>               ; "PUT", <xref target="PUT"/>
440                 / <x:abnf-char-sequence>"DELETE"</x:abnf-char-sequence>      ; "DELETE", <xref target="DELETE"/>
441                 / <x:abnf-char-sequence>"TRACE"</x:abnf-char-sequence>         ; "TRACE", <xref target="TRACE"/>
442                 / <x:abnf-char-sequence>"CONNECT"</x:abnf-char-sequence>   ; "CONNECT", <xref target="CONNECT"/>
443                 / <x:ref>extension-method</x:ref>
444  <x:ref>extension-method</x:ref> = <x:ref>token</x:ref>
445</artwork></figure>
446<t>
447   The list of methods allowed by a resource can be specified in an
448   Allow header field (<xref target="header.allow"/>). The status code of the response
449   always notifies the client whether a method is currently allowed on a
450   resource, since the set of allowed methods can change dynamically. An
451   origin server &SHOULD; respond with the status code 405 (Method Not Allowed)
452   if the method is known by the origin server but not allowed for the
453   resource, and 501 (Not Implemented) if the method is
454   unrecognized or not implemented by the origin server. The methods GET
455   and HEAD &MUST; be supported by all general-purpose servers. All other
456   methods are &OPTIONAL;; however, if the above methods are implemented,
457   they &MUST; be implemented with the same semantics as those specified
458   in <xref target="method.definitions"/>.
459</t>
460
461<section title="Method Registry" anchor="method.registry">
462<t>
463  The HTTP Method Registry defines the name space for the Method token in the
464  Request line of an HTTP request.
465</t>
466<t>
467  Registrations &MUST; include the following fields:
468  <list style="symbols">
469    <t>Method Name (see <xref target="method"/>)</t>
470    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
471    <t>Pointer to specification text</t>
472  </list>
473</t>
474<t>
475  Values to be added to this name space are subject to IETF review
476  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
477</t>
478<t>
479  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
480</t>
481
482<section title="Considerations for New Methods" anchor="considerations.for.new.methods">
483<t>
484   When it is necessary to express new semantics for a HTTP request that
485   aren't specific to a single application or media type, and currently defined
486   methods are inadequate, it may be appropriate to register a new method.
487</t>
488<t>
489   HTTP methods are generic; that is, they are potentially applicable to any
490   resource, not just one particular media type, "type" of resource, or
491   application. As such, it is preferred that new HTTP methods be registered
492   in a document that isn't specific to a single application, so that this is
493   clear.
494</t>
495<t>
496   Due to the parsing rules defined in &message-body;, definitions of HTTP
497   methods cannot prohibit the presence of a message-body on either the request
498   or the response message (with responses to HEAD requests being the single
499   exception). Definitions of new methods cannot change this rule, but they can
500   specify that only zero-length bodies (as opposed to absent bodies) are allowed.
501</t>
502<t>
503   New method definitions need to indicate whether they are safe (<xref
504   target="safe.methods"/>) and whether they are idempotent (<xref
505   target="idempotent.methods"/>). They also need to state whether they can be
506   cached (&caching;); in particular what conditions a cache may store the
507   response, and under what conditions such a stored response may be used to
508   satisfy a subsequent request.
509</t>
510</section>
511
512</section>
513</section>
514
515<section title="Request Header Fields" anchor="request.header.fields">
516  <x:anchor-alias value="request-header"/>
517<t>
518   The request-header fields allow the client to pass additional
519   information about the request, and about the client itself, to the
520   server. These fields act as request modifiers, with semantics
521   equivalent to the parameters on a programming language method
522   invocation.
523</t>
524<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="request-header"/>
525  <x:ref>request-header</x:ref> = <x:ref>Accept</x:ref>                   ; &header-accept;
526                 / <x:ref>Accept-Charset</x:ref>           ; &header-accept-charset;
527                 / <x:ref>Accept-Encoding</x:ref>          ; &header-accept-encoding;
528                 / <x:ref>Accept-Language</x:ref>          ; &header-accept-language;
529                 / <x:ref>Authorization</x:ref>            ; &header-authorization;
530                 / <x:ref>Expect</x:ref>                   ; <xref target="header.expect"/>
531                 / <x:ref>From</x:ref>                     ; <xref target="header.from"/>
532                 / <x:ref>Host</x:ref>                     ; &header-host;
533                 / <x:ref>If-Match</x:ref>                 ; &header-if-match;
534                 / <x:ref>If-Modified-Since</x:ref>        ; &header-if-modified-since;
535                 / <x:ref>If-None-Match</x:ref>            ; &header-if-none-match;
536                 / <x:ref>If-Range</x:ref>                 ; &header-if-range;
537                 / <x:ref>If-Unmodified-Since</x:ref>      ; &header-if-unmodified-since;
538                 / <x:ref>Max-Forwards</x:ref>             ; <xref target="header.max-forwards"/>
539                 / <x:ref>Proxy-Authorization</x:ref>      ; &header-proxy-authorization;
540                 / <x:ref>Range</x:ref>                    ; &header-range;
541                 / <x:ref>Referer</x:ref>                  ; <xref target="header.referer"/>
542                 / <x:ref>TE</x:ref>                       ; &header-te;
543                 / <x:ref>User-Agent</x:ref>               ; <xref target="header.user-agent"/>
544</artwork></figure>
545<t>
546   Request-header field names can be extended reliably only in
547   combination with a change in the protocol version. However, new or
548   experimental header fields &MAY; be given the semantics of request-header
549   fields if all parties in the communication recognize them to
550   be request-header fields.
551</t>
552</section>
553
554<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
555  <x:anchor-alias value="Reason-Phrase"/>
556  <x:anchor-alias value="Status-Code"/>
557  <x:anchor-alias value="extension-code"/>
558<t>
559   The Status-Code element is a 3-digit integer result code of the
560   attempt to understand and satisfy the request. The status codes listed
561   below are defined in <xref target="status.codes"/>, &p4-status-codes;,
562   &p5-status-codes;, and &p7-status-codes;.
563</t>
564<t>
565   The Reason-Phrase is intended to give a short
566   textual description of the Status-Code. The Status-Code is intended
567   for use by automata and the Reason-Phrase is intended for the human
568   user. The client is not required to examine or display the Reason-Phrase.
569</t>
570<t> 
571   The individual values of the numeric status codes defined for
572   HTTP/1.1, and an example set of corresponding Reason-Phrase values, are
573   presented below. The reason phrases listed here are only
574   recommendations -- they &MAY; be replaced by local equivalents without
575   affecting the protocol.
576</t>
577<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"/>
578  <x:ref>Status-Code</x:ref> =
579       "100"  ; <xref target="status.100"/>: Continue
580     / "101"  ; <xref target="status.101"/>: Switching Protocols
581     / "200"  ; <xref target="status.200"/>: OK
582     / "201"  ; <xref target="status.201"/>: Created
583     / "202"  ; <xref target="status.202"/>: Accepted
584     / "203"  ; <xref target="status.203"/>: Non-Authoritative Information
585     / "204"  ; <xref target="status.204"/>: No Content
586     / "205"  ; <xref target="status.205"/>: Reset Content
587     / "206"  ; &status-206;: Partial Content
588     / "300"  ; <xref target="status.300"/>: Multiple Choices
589     / "301"  ; <xref target="status.301"/>: Moved Permanently
590     / "302"  ; <xref target="status.302"/>: Found
591     / "303"  ; <xref target="status.303"/>: See Other
592     / "304"  ; &status-304;: Not Modified
593     / "305"  ; <xref target="status.305"/>: Use Proxy
594     / "307"  ; <xref target="status.307"/>: Temporary Redirect
595     / "400"  ; <xref target="status.400"/>: Bad Request
596     / "401"  ; &status-401;: Unauthorized
597     / "402"  ; <xref target="status.402"/>: Payment Required
598     / "403"  ; <xref target="status.403"/>: Forbidden
599     / "404"  ; <xref target="status.404"/>: Not Found
600     / "405"  ; <xref target="status.405"/>: Method Not Allowed
601     / "406"  ; <xref target="status.406"/>: Not Acceptable
602     / "407"  ; &status-407;: Proxy Authentication Required
603     / "408"  ; <xref target="status.408"/>: Request Time-out
604     / "409"  ; <xref target="status.409"/>: Conflict
605     / "410"  ; <xref target="status.410"/>: Gone
606     / "411"  ; <xref target="status.411"/>: Length Required
607     / "412"  ; &status-412;: Precondition Failed
608     / "413"  ; <xref target="status.413"/>: Request Entity Too Large
609     / "414"  ; <xref target="status.414"/>: URI Too Long
610     / "415"  ; <xref target="status.415"/>: Unsupported Media Type
611     / "416"  ; &status-416;: Requested range not satisfiable
612     / "417"  ; <xref target="status.417"/>: Expectation Failed
613     / "500"  ; <xref target="status.500"/>: Internal Server Error
614     / "501"  ; <xref target="status.501"/>: Not Implemented
615     / "502"  ; <xref target="status.502"/>: Bad Gateway
616     / "503"  ; <xref target="status.503"/>: Service Unavailable
617     / "504"  ; <xref target="status.504"/>: Gateway Time-out
618     / "505"  ; <xref target="status.505"/>: HTTP Version not supported
619     / <x:ref>extension-code</x:ref>
620
621  <x:ref>extension-code</x:ref> = 3<x:ref>DIGIT</x:ref>
622  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
623</artwork></figure>
624<t>
625   HTTP status codes are extensible. HTTP applications are not required
626   to understand the meaning of all registered status codes, though such
627   understanding is obviously desirable. However, applications &MUST;
628   understand the class of any status code, as indicated by the first
629   digit, and treat any unrecognized response as being equivalent to the
630   x00 status code of that class, with the exception that an
631   unrecognized response &MUST-NOT; be cached. For example, if an
632   unrecognized status code of 431 is received by the client, it can
633   safely assume that there was something wrong with its request and
634   treat the response as if it had received a 400 status code. In such
635   cases, user agents &SHOULD; present to the user the representation enclosed
636   with the response, since that representation is likely to include human-readable
637   information which will explain the unusual status.
638</t>
639
640<section title="Status Code Registry" anchor="status.code.registry">
641<t>
642  The HTTP Status Code Registry defines the name space for the Status-Code
643  token in the Status-Line of an HTTP response.
644</t>
645<t>
646  Values to be added to this name space are subject to IETF review
647  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
648</t>
649<t>
650  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
651</t>
652
653<section title="Considerations for New Status Codes" anchor="considerations.for.new.status.codes">
654<t>
655   When it is necessary to express new semantics for a HTTP response that
656   aren't specific to a single application or media type, and currently defined
657   status codes are inadequate, a new status code can be registered.
658</t>
659<t>
660   HTTP status codes are generic; that is, they are potentially applicable to
661   any resource, not just one particular media type, "type" of resource, or
662   application. As such, it is preferred that new HTTP status codes be
663   registered in a document that isn't specific to a single application, so
664   that this is clear.
665</t>
666<t>
667   Definitions of new HTTP status codes typically explain the request
668   conditions that produce a response containing the status code (e.g.,
669   combinations of request headers and/or method(s)), along with any
670   interactions with response headers (e.g., those that are required, those
671   that modify the semantics of the response).
672</t>
673<t>
674   New HTTP status codes are required to fall under one of the categories
675   defined in <xref target="status.codes"/>. To allow existing parsers to
676   properly handle them, new status codes cannot disallow a response body,
677   although they can mandate a zero-length response body. They can require the
678   presence of one or more particular HTTP response header(s).
679</t>
680<t>
681   Likewise, their definitions can specify that caches are allowed to use
682   heuristics to determine their freshness (see &caching;; by default, it is
683   not allowed), and can define how to determine the resource which they
684   carry a representation for (see <xref
685   target="identifying.response.associated.with.representation"/>; by default,
686   it is anonymous).
687</t>
688</section>
689
690</section>
691
692</section>
693
694<section title="Response Header Fields" anchor="response.header.fields">
695  <x:anchor-alias value="response-header"/>
696<t>
697   The response-header fields allow the server to pass additional
698   information about the response which cannot be placed in the Status-Line.
699   These header fields give information about the server and about
700   further access to the target resource (&effective-request-uri;).
701</t>
702<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="response-header"/>
703  <x:ref>response-header</x:ref> = <x:ref>Accept-Ranges</x:ref>           ; &header-accept-ranges;
704                  / <x:ref>Age</x:ref>                     ; &header-age;
705                  / <x:ref>Allow</x:ref>                   ; <xref target="header.allow"/>
706                  / <x:ref>ETag</x:ref>                    ; &header-etag;
707                  / <x:ref>Location</x:ref>                ; <xref target="header.location"/>
708                  / <x:ref>Proxy-Authenticate</x:ref>      ; &header-proxy-authenticate;
709                  / <x:ref>Retry-After</x:ref>             ; <xref target="header.retry-after"/>
710                  / <x:ref>Server</x:ref>                  ; <xref target="header.server"/>
711                  / <x:ref>Vary</x:ref>                    ; &header-vary;
712                  / <x:ref>WWW-Authenticate</x:ref>        ; &header-www-authenticate;
713</artwork></figure>
714<t>
715   Response-header field names can be extended reliably only in
716   combination with a change in the protocol version. However, new or
717   experimental header fields &MAY; be given the semantics of response-header
718   fields if all parties in the communication recognize them to
719   be response-header fields.
720</t>
721</section>
722
723<section title="Representation" anchor="representation">
724<t>
725   Request and Response messages &MAY; transfer a representation if not otherwise
726   restricted by the request method or response status code. A representation
727   consists of metadata (representation header fields) and data (representation
728   body).  When a complete or partial representation is enclosed in an HTTP message,
729   it is referred to as the payload of the message. HTTP representations
730   are defined in &payload;.
731</t>
732<t>
733   A representation body is only present in a message when a message-body is
734   present, as described in &message-body;. The representation body is obtained
735   from the message-body by decoding any Transfer-Encoding that might
736   have been applied to ensure safe and proper transfer of the message.
737</t>
738
739<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
740<t>
741   It is sometimes necessary to determine an identifier for the resource
742   associated with a representation.
743</t>
744<t>
745   An HTTP request representation, when present, is always associated with an
746   anonymous (i.e., unidentified) resource.
747</t>
748<t>
749   In the common case, an HTTP response is a representation of the target
750   resource (see &effective-request-uri;). However, this is not always the
751   case. To determine the URI of the resource a response is associated with,
752   the following rules are used (with the first applicable one being selected):
753</t>
754<t><list style="numbers">
755   <t>If the response status code is 200 or 203 and the request method was GET,
756   the response payload is a representation of the target resource.</t>
757   <t>If the response status code is 204, 206, or 304 and the request method was GET
758   or HEAD, the response payload is a partial representation of the target
759   (see &combining-responses;).</t>
760   <t>If the response has a Content-Location header field, and that URI is the same
761   as the effective request URI, the response payload is a representation of the
762   target resource.</t>
763   <t>If the response has a Content-Location header field, and that URI is not the
764   same as the effective request URI, then the response asserts that its
765   payload is a representation of the resource identified by the
766   Content-Location URI. However, such an assertion cannot be trusted unless
767   it can be verified by other means (not defined by HTTP).</t>
768   <t>Otherwise, the response is a representation of an anonymous (i.e.,
769   unidentified) resource.</t>
770</list></t>
771<t>
772  <cref anchor="TODO-req-uri">
773   The comparison function is going to have to be defined somewhere,
774   because we already need to compare URIs for things like cache invalidation.</cref>
775</t>
776</section>
777
778</section>
779
780
781<section title="Method Definitions" anchor="method.definitions">
782<t>
783   The set of common methods for HTTP/1.1 is defined below. Although
784   this set can be expanded, additional methods cannot be assumed to
785   share the same semantics for separately extended clients and servers.
786</t>
787
788<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
789
790<section title="Safe Methods" anchor="safe.methods">
791<iref item="Safe Methods" primary="true"/>
792<t>
793   Implementors need to be aware that the software represents the user in
794   their interactions over the Internet, and need to allow
795   the user to be aware of any actions they take which might have an
796   unexpected significance to themselves or others.
797</t>
798<t>
799   In particular, the convention has been established that the GET, HEAD,
800   OPTIONS, and TRACE methods &SHOULD-NOT; have the significance of taking an action
801   other than retrieval. These methods ought to be considered "<x:dfn anchor="safe">safe</x:dfn>".
802   This allows user agents to represent other methods, such as POST, PUT
803   and DELETE, in a special way, so that the user is made aware of the
804   fact that a possibly unsafe action is being requested.
805</t>
806<t>
807   Naturally, it is not possible to ensure that the server does not
808   generate side-effects as a result of performing a GET request; in
809   fact, some dynamic resources consider that a feature. The important
810   distinction here is that the user did not request the side-effects,
811   so therefore cannot be held accountable for them.
812</t>
813</section>
814
815<section title="Idempotent Methods" anchor="idempotent.methods">
816<iref item="Idempotent Methods" primary="true"/>
817<t>
818   Methods can also have the property of "idempotence" in that, aside
819   from error or expiration issues, the intended effect of multiple
820   identical requests is the same as for a single request.
821   The methods PUT, DELETE, and all safe methods are idempotent.
822   It is important to note that idempotence refers only to changes
823   requested by the client: a server is free to change its state due
824   to multiple requests for the purpose of tracking those requests,
825   versioning of results, etc.
826</t>
827</section>
828</section>
829
830<section title="OPTIONS" anchor="OPTIONS">
831  <rdf:Description>
832    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
833  </rdf:Description>
834  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
835  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
836<t>
837   The OPTIONS method represents a request for information about the
838   communication options available on the request/response chain
839   identified by the effective request URI. This method allows the client to
840   determine the options and/or requirements associated with a resource,
841   or the capabilities of a server, without implying a resource action
842   or initiating a resource retrieval.
843</t>
844<t>
845   Responses to this method are not cacheable.
846</t>
847<t>
848   If the OPTIONS request includes a message-body (as indicated by the
849   presence of Content-Length or Transfer-Encoding), then the media type
850   &MUST; be indicated by a Content-Type field. Although this
851   specification does not define any use for such a body, future
852   extensions to HTTP might use the OPTIONS body to make more detailed
853   queries on the server.
854</t>
855<t>
856   If the request-target is an asterisk ("*"), the OPTIONS request is
857   intended to apply to the server in general rather than to a specific
858   resource. Since a server's communication options typically depend on
859   the resource, the "*" request is only useful as a "ping" or "no-op"
860   type of method; it does nothing beyond allowing the client to test
861   the capabilities of the server. For example, this can be used to test
862   a proxy for HTTP/1.1 compliance (or lack thereof).
863</t>
864<t>
865   If the request-target is not an asterisk, the OPTIONS request applies
866   only to the options that are available when communicating with that
867   resource.
868</t>
869<t>
870   A 200 response &SHOULD; include any header fields that indicate
871   optional features implemented by the server and applicable to that
872   resource (e.g., Allow), possibly including extensions not defined by
873   this specification. The response body, if any, &SHOULD; also include
874   information about the communication options. The format for such a
875   body is not defined by this specification, but might be defined by
876   future extensions to HTTP. Content negotiation &MAY; be used to select
877   the appropriate response format. If no response body is included, the
878   response &MUST; include a Content-Length field with a field-value of
879   "0".
880</t>
881<t>
882   The Max-Forwards request-header field &MAY; be used to target a
883   specific proxy in the request chain (see <xref target="header.max-forwards"/>).
884   If no Max-Forwards field is present in the request, then the forwarded
885   request &MUST-NOT; include a Max-Forwards field.
886</t>
887</section>
888
889<section title="GET" anchor="GET">
890  <rdf:Description>
891    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
892  </rdf:Description>
893  <iref primary="true" item="GET method" x:for-anchor=""/>
894  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
895<t>
896   The GET method means retrieve whatever information (in the form of a
897   representation) currently corresponds to the target resource.
898</t>
899<t>   
900   If the target resource is a data-producing process, it is the
901   produced data which shall be returned as the representation in the response and not
902   the source text of the process, unless that text happens to be the output of
903   the process.
904</t>
905<t>
906   The semantics of the GET method change to a "conditional GET" if the
907   request message includes an If-Modified-Since, If-Unmodified-Since,
908   If-Match, If-None-Match, or If-Range header field. A conditional GET
909   method requests that the representation be transferred only under the
910   circumstances described by the conditional header field(s). The
911   conditional GET method is intended to reduce unnecessary network
912   usage by allowing cached representations to be refreshed without requiring
913   multiple requests or transferring data already held by the client.
914</t>
915<t>
916   The semantics of the GET method change to a "partial GET" if the
917   request message includes a Range header field. A partial GET requests
918   that only part of the representation be transferred, as described in &header-range;.
919   The partial GET method is intended to reduce unnecessary
920   network usage by allowing partially-retrieved representations to be
921   completed without transferring data already held by the client.
922</t>
923<t>
924   The response to a GET request is cacheable and &MAY; be used to satisfy
925   subsequent GET and HEAD requests (see &caching;).
926</t>
927<t>
928   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
929</t>
930</section>
931
932<section title="HEAD" anchor="HEAD">
933  <rdf:Description>
934    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
935  </rdf:Description>
936  <iref primary="true" item="HEAD method" x:for-anchor=""/>
937  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
938<t>
939   The HEAD method is identical to GET except that the server &MUST-NOT;
940   return a message-body in the response. The metadata contained
941   in the HTTP header fields in response to a HEAD request &SHOULD; be identical
942   to the information sent in response to a GET request. This method can
943   be used for obtaining metadata about the representation implied by the
944   request without transferring the representation body. This method is
945   often used for testing hypertext links for validity, accessibility,
946   and recent modification.
947</t>
948<t>
949   The response to a HEAD request is cacheable and &MAY; be used to satisfy
950   a subsequent HEAD request; see &caching;. It also &MAY; be used to update a previously cached
951   representation from that resource; if the new field values
952   indicate that the cached representation differs from the current representation (as
953   would be indicated by a change in Content-Length, Content-MD5, ETag
954   or Last-Modified), then the cache &MUST; treat the cache entry as
955   stale.
956</t>
957</section>
958
959<section title="POST" anchor="POST">
960  <iref primary="true" item="POST method" x:for-anchor=""/>
961  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
962<t>
963   The POST method is used to request that the origin server accept the
964   representation enclosed in the request as data to be processed by the
965   target resource. POST is designed to allow a uniform method to cover the
966   following functions:
967  <list style="symbols">
968    <t>
969      Annotation of existing resources;
970    </t>
971    <t>
972        Posting a message to a bulletin board, newsgroup, mailing list,
973        or similar group of articles;
974    </t>
975    <t>
976        Providing a block of data, such as the result of submitting a
977        form, to a data-handling process;
978    </t>
979    <t>
980        Extending a database through an append operation.
981    </t>
982  </list>
983</t>
984<t>
985   The actual function performed by the POST method is determined by the
986   server and is usually dependent on the effective request URI.
987</t>
988<t>
989   The action performed by the POST method might not result in a
990   resource that can be identified by a URI. In this case, either 200
991   (OK) or 204 (No Content) is the appropriate response status code,
992   depending on whether or not the response includes a representation that
993   describes the result.
994</t>
995<t>
996   If a resource has been created on the origin server, the response
997   &SHOULD; be 201 (Created) and contain a representation which describes the
998   status of the request and refers to the new resource, and a Location
999   header field (see <xref target="header.location"/>).
1000</t>
1001<t>
1002   Responses to POST requests are only cacheable when they
1003   include explicit freshness information (see &p6-explicit;). A
1004   cached POST response with a Content-Location header field
1005   (see &header-content-location;) whose value is the effective
1006   Request URI &MAY; be used to satisfy subsequent GET and HEAD requests.
1007</t>
1008<t>
1009   Note that POST caching is not widely implemented.
1010   However, the 303 (See Other) response can be used to direct the
1011   user agent to retrieve a cacheable resource.
1012</t>
1013</section>
1014
1015<section title="PUT" anchor="PUT">
1016  <iref primary="true" item="PUT method" x:for-anchor=""/>
1017  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
1018<t>
1019   The PUT method requests that the enclosed representation be stored at the
1020   effective request URI. If the effective request URI refers to an already
1021   existing resource, the enclosed representation &SHOULD; be considered a
1022   modified version of the one residing on the origin server. Otherwise, if the
1023   effective request URI does not point to an existing resource, and that URI is
1024   capable of being defined as a new resource by the requesting user
1025   agent, the origin server can create the resource with that URI.
1026</t>
1027<t>   
1028   If a new resource is created at the effective request URI, the origin
1029   server &MUST; inform the user agent
1030   via the 201 (Created) response. If an existing resource is modified,
1031   either the 200 (OK) or 204 (No Content) response codes &SHOULD; be sent
1032   to indicate successful completion of the request.
1033</t>
1034<t>   
1035   If the target resource could not be created or modified, an appropriate
1036   error response &SHOULD; be given that reflects the nature of the problem.
1037   The recipient of the representation &MUST-NOT; ignore any Content-*
1038   header fields (headers starting with the prefix "Content-") that it does
1039   not understand or implement
1040   and &MUST; return a 501 (Not Implemented) response in such cases.
1041</t>
1042<t>
1043   If the request passes through a cache that has one or more stored
1044   responses for the effective request URI, those stored responses
1045   &SHOULD; be marked as stale if the response to the PUT request
1046   has a success status code. Responses to the PUT method are
1047   not cacheable.
1048</t>
1049<t>
1050   The fundamental difference between the POST and PUT requests is
1051   reflected in the different meaning of the effective request URI. The URI in a
1052   POST request identifies the resource that will handle the enclosed
1053   representation. That resource might be a data-accepting process, a gateway to
1054   some other protocol, or a document that accepts annotations.
1055   In contrast, the URI in a PUT request identifies the resource for
1056   which enclosed representation is a new or replacement value; the
1057   user agent knows what URI is intended and the server &MUST-NOT; attempt
1058   to apply the request to some other resource.
1059   If the server desires that the request be applied to a different URI,
1060   it &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
1061   then make its own decision regarding whether or not to redirect the
1062   request.
1063</t>
1064<t>
1065   A single resource &MAY; be identified by many different URIs. For
1066   example, an article might have a URI for identifying "the current
1067   version" which is separate from the URI identifying each particular
1068   version. In this case, a PUT request on a general URI might result in
1069   several other URIs being defined by the origin server.
1070</t>
1071<t>
1072   HTTP/1.1 does not define how a PUT method affects the state of an
1073   origin server.
1074</t>
1075<t>
1076   Header fields in a PUT request that are recognized as representation
1077   metadata &SHOULD; be applied to the resource created or modified by
1078   the PUT.  Unrecognized header fields &SHOULD; be ignored.
1079</t>
1080</section>
1081
1082<section title="DELETE" anchor="DELETE">
1083  <iref primary="true" item="DELETE method" x:for-anchor=""/>
1084  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
1085<t>
1086   The DELETE method requests that the origin server delete the target
1087   resource. This method &MAY; be overridden by
1088   human intervention (or other means) on the origin server. The client cannot
1089   be guaranteed that the operation has been carried out, even if the
1090   status code returned from the origin server indicates that the action
1091   has been completed successfully. However, the server &SHOULD-NOT; 
1092   indicate success unless, at the time the response is given, it
1093   intends to delete the resource or move it to an inaccessible
1094   location.
1095</t>
1096<t>
1097   A successful response &SHOULD; be 200 (OK) if the response includes an
1098   representation describing the status, 202 (Accepted) if the action has not
1099   yet been enacted, or 204 (No Content) if the action has been enacted
1100   but the response does not include a representation.
1101</t>
1102<t>
1103   If the request passes through a cache and the effective request URI
1104   identifies one or more currently cached representations, those entries &SHOULD; be
1105   treated as stale. Responses to the DELETE method are not cacheable.
1106</t>
1107</section>
1108
1109<section title="TRACE" anchor="TRACE">
1110  <rdf:Description>
1111    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1112  </rdf:Description>
1113  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1114  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1115<t>
1116   The TRACE method is used to invoke a remote, application-layer loop-back
1117   of the request message. The final recipient of the request
1118   &SHOULD; reflect the message received back to the client as the
1119   message-body of a 200 (OK) response. The final recipient is either the
1120   origin server or the first proxy or gateway to receive a Max-Forwards
1121   value of zero (0) in the request (see <xref target="header.max-forwards"/>).
1122   A TRACE request &MUST-NOT; include a message-body.
1123</t>
1124<t>
1125   TRACE allows the client to see what is being received at the other
1126   end of the request chain and use that data for testing or diagnostic
1127   information. The value of the Via header field (&header-via;) is of
1128   particular interest, since it acts as a trace of the request chain.
1129   Use of the Max-Forwards header field allows the client to limit the
1130   length of the request chain, which is useful for testing a chain of
1131   proxies forwarding messages in an infinite loop.
1132</t>
1133<t>
1134   If the request is valid, the response &SHOULD; have a Content-Type of
1135   "message/http" (see &media-type-message-http;) and contain a message-body
1136   that encloses a copy of the entire request message.
1137   Responses to the TRACE method are not cacheable.
1138</t>
1139</section>
1140
1141<section title="CONNECT" anchor="CONNECT">
1142  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1143  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1144<t>
1145   This specification reserves the method name CONNECT for use with a
1146   proxy that can dynamically switch to being a tunnel (e.g., SSL
1147   tunneling <xref target="RFC2817"/>).
1148</t>
1149</section>
1150</section>
1151
1152
1153<section title="Status Code Definitions" anchor="status.codes">
1154<t>
1155   Each Status-Code is described below, including any metadata required
1156   in the response.
1157</t>
1158
1159<section title="Informational 1xx" anchor="status.1xx">
1160<t>
1161   This class of status code indicates a provisional response,
1162   consisting only of the Status-Line and optional header fields, and is
1163   terminated by an empty line. There are no required header fields for this
1164   class of status code. Since HTTP/1.0 did not define any 1xx status
1165   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1166   except under experimental conditions.
1167</t>
1168<t>
1169   A client &MUST; be prepared to accept one or more 1xx status responses
1170   prior to a regular response, even if the client does not expect a 100
1171   (Continue) status message. Unexpected 1xx status responses &MAY; be
1172   ignored by a user agent.
1173</t>
1174<t>
1175   Proxies &MUST; forward 1xx responses, unless the connection between the
1176   proxy and its client has been closed, or unless the proxy itself
1177   requested the generation of the 1xx response. (For example, if a
1178   proxy adds a "Expect: 100-continue" field when it forwards a request,
1179   then it need not forward the corresponding 100 (Continue)
1180   response(s).)
1181</t>
1182
1183<section title="100 Continue" anchor="status.100">
1184  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1185  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1186<t>
1187   The client &SHOULD; continue with its request. This interim response is
1188   used to inform the client that the initial part of the request has
1189   been received and has not yet been rejected by the server. The client
1190   &SHOULD; continue by sending the remainder of the request or, if the
1191   request has already been completed, ignore this response. The server
1192   &MUST; send a final response after the request has been completed. See
1193   &use100; for detailed discussion of the use and handling of this
1194   status code.
1195</t>
1196</section>
1197
1198<section title="101 Switching Protocols" anchor="status.101">
1199  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1200  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1201<t>
1202   The server understands and is willing to comply with the client's
1203   request, via the Upgrade message header field (&header-upgrade;), for a
1204   change in the application protocol being used on this connection. The
1205   server will switch protocols to those defined by the response's
1206   Upgrade header field immediately after the empty line which
1207   terminates the 101 response.
1208</t>
1209<t>
1210   The protocol &SHOULD; be switched only when it is advantageous to do
1211   so. For example, switching to a newer version of HTTP is advantageous
1212   over older versions, and switching to a real-time, synchronous
1213   protocol might be advantageous when delivering resources that use
1214   such features.
1215</t>
1216</section>
1217</section>
1218
1219<section title="Successful 2xx" anchor="status.2xx">
1220<t>
1221   This class of status code indicates that the client's request was
1222   successfully received, understood, and accepted.
1223</t>
1224
1225<section title="200 OK" anchor="status.200">
1226  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1227  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1228<t>
1229   The request has succeeded. The payload returned with the response
1230   is dependent on the method used in the request, for example:
1231  <list style="hanging">
1232    <t hangText="GET">
1233          a representation of the target resource is sent in the response;
1234    </t>
1235    <t hangText="HEAD">
1236          the same representation as GET, except without the message-body;
1237    </t>
1238    <t hangText="POST">
1239      a representation describing or containing the result of the action;
1240    </t>
1241    <t hangText="TRACE">
1242      a representation containing the request message as received by the
1243      end server.
1244    </t>
1245  </list>
1246</t>
1247<t>
1248   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1249   freshness for 200 responses.
1250</t>
1251</section>
1252
1253<section title="201 Created" anchor="status.201">
1254  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1255  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1256<t>
1257   The request has been fulfilled and has resulted in a new resource being
1258   created. The newly created resource can be referenced by the URI(s)
1259   returned in the payload of the response, with the most specific URI
1260   for the resource given by a Location header field. The response
1261   &SHOULD; include a payload containing a list of resource
1262   characteristics and location(s) from which the user or user agent can
1263   choose the one most appropriate. The payload format is specified by
1264   the media type given in the Content-Type header field. The origin
1265   server &MUST; create the resource before returning the 201 status code.
1266   If the action cannot be carried out immediately, the server &SHOULD;
1267   respond with 202 (Accepted) response instead.
1268</t>
1269<t>
1270   A 201 response &MAY; contain an ETag response header field indicating
1271   the current value of the entity-tag for the representation of the resource
1272   just created (see &header-etag;).
1273</t>
1274</section>
1275
1276<section title="202 Accepted" anchor="status.202">
1277  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1278  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1279<t>
1280   The request has been accepted for processing, but the processing has
1281   not been completed.  The request might or might not eventually be
1282   acted upon, as it might be disallowed when processing actually takes
1283   place. There is no facility for re-sending a status code from an
1284   asynchronous operation such as this.
1285</t>
1286<t>
1287   The 202 response is intentionally non-committal. Its purpose is to
1288   allow a server to accept a request for some other process (perhaps a
1289   batch-oriented process that is only run once per day) without
1290   requiring that the user agent's connection to the server persist
1291   until the process is completed. The representation returned with this
1292   response &SHOULD; include an indication of the request's current status
1293   and either a pointer to a status monitor or some estimate of when the
1294   user can expect the request to be fulfilled.
1295</t>
1296</section>
1297
1298<section title="203 Non-Authoritative Information" anchor="status.203">
1299  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1300  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1301<t>
1302   The returned metadata in the header fields is not the
1303   definitive set as available from the origin server, but is gathered
1304   from a local or a third-party copy. The set presented &MAY; be a subset
1305   or superset of the original version. For example, including local
1306   annotation information about the resource might result in a superset
1307   of the metadata known by the origin server. Use of this
1308   response code is not required and is only appropriate when the
1309   response would otherwise be 200 (OK).
1310</t>
1311<t>
1312   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1313   freshness for 203 responses.
1314</t>
1315
1316</section>
1317
1318<section title="204 No Content" anchor="status.204">
1319  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1320  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1321<t>
1322   The server has successfully fulfilled the request, but there is no
1323   additional content to return in the response payload body.  The
1324   resource metadata and representation metadata in the response message's
1325   header fields refer to the target resource
1326   and its current representation, respectively, after the requested action.
1327   For example, if a 204 status code is received in response to a PUT
1328   and the response contains an ETag header field, then the value of
1329   that field is the current entity-tag for the representation that
1330   was successfully PUT.
1331</t>
1332<t>
1333   If the client is a user agent, it &SHOULD-NOT; change its document view
1334   from that which caused the request to be sent. This response is
1335   primarily intended to allow input for actions to take place without
1336   causing a change to the user agent's active document view, although
1337   any new or updated metadata &SHOULD; be applied to the document
1338   currently in the user agent's active view.
1339</t>
1340<t>
1341   The 204 response &MUST-NOT; include a message-body, and thus is always
1342   terminated by the first empty line after the header fields.
1343</t>
1344</section>
1345
1346<section title="205 Reset Content" anchor="status.205">
1347  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1348  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1349<t>
1350   The server has fulfilled the request and the user agent &SHOULD; reset
1351   the document view which caused the request to be sent. This response
1352   is primarily intended to allow input for actions to take place via
1353   user input, followed by a clearing of the form in which the input is
1354   given so that the user can easily initiate another input action. The
1355   response &MUST-NOT; include a message-body.
1356</t>
1357</section>
1358
1359<section title="206 Partial Content" anchor="status.206">
1360  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1361  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1362  <rdf:Description>
1363    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1364  </rdf:Description>
1365<t>
1366   The server has fulfilled the partial GET request for the resource
1367   and the enclosed payload is a partial representation as defined in &status-206;.
1368</t>
1369<t>
1370   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1371   freshness for 206 responses.
1372</t>
1373</section>
1374</section>
1375
1376<section title="Redirection 3xx" anchor="status.3xx">
1377<t>
1378   This class of status code indicates that further action needs to be
1379   taken by the user agent in order to fulfill the request.  The action
1380   required &MAY; be carried out by the user agent without interaction
1381   with the user if and only if the method used in the second request is
1382   known to be "safe", as defined in <xref target="safe.methods"/>.
1383   A client &SHOULD; detect infinite redirection loops, since such loops
1384   generate network traffic for each redirection.
1385</t>
1386<x:note>
1387  <t>
1388    <x:h>Note:</x:h> An earlier version of this specification recommended a
1389    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1390    Content developers need to be aware that some clients might
1391    implement such a fixed limitation.
1392  </t>
1393</x:note>
1394
1395<section title="300 Multiple Choices" anchor="status.300">
1396  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1397  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1398<t>
1399   The target resource has more than one
1400   representation, each with its own specific location, and agent-driven
1401   negotiation information (&content-negotiation;) is being provided so that
1402   the user (or user agent) can select a preferred representation by
1403   redirecting its request to that location.
1404</t>
1405<t>
1406   Unless it was a HEAD request, the response &SHOULD; include a representation
1407   containing a list of representation metadata and location(s) from
1408   which the user or user agent can choose the one most appropriate. The
1409   data format is specified by the media type given in the Content-Type
1410   header field. Depending upon the format and the capabilities of
1411   the user agent, selection of the most appropriate choice &MAY; be
1412   performed automatically. However, this specification does not define
1413   any standard for such automatic selection.
1414</t>
1415<t>
1416   If the server has a preferred choice of representation, it &SHOULD;
1417   include the specific URI for that representation in the Location
1418   field; user agents &MAY; use the Location field value for automatic
1419   redirection.
1420</t>
1421<t>
1422   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1423   freshness for 300 responses.
1424</t>
1425
1426</section>
1427
1428<section title="301 Moved Permanently" anchor="status.301">
1429  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1430  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1431<t>
1432   The target resource has been assigned a new permanent URI and any
1433   future references to this resource &SHOULD; use one of the returned
1434   URIs.  Clients with link editing capabilities ought to automatically
1435   re-link references to the effective request URI to one or more of the new
1436   references returned by the server, where possible.
1437</t>
1438<t>
1439   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1440   freshness for 301 responses.
1441</t>
1442<t>
1443   The new permanent URI &SHOULD; be given by the Location field in the
1444   response. Unless the request method was HEAD, the representation of the
1445   response &SHOULD; contain a short hypertext note with a hyperlink to
1446   the new URI(s).
1447</t>
1448<t>
1449   If the 301 status code is received in response to a request method
1450   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1451   then the request &MAY; be automatically redirected by the user agent without
1452   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1453   request unless it can be confirmed by the user, since this might
1454   change the conditions under which the request was issued.
1455</t>
1456<x:note>
1457  <t>
1458    <x:h>Note:</x:h> When automatically redirecting a POST request after
1459    receiving a 301 status code, some existing HTTP/1.0 user agents
1460    will erroneously change it into a GET request.
1461  </t>
1462</x:note>
1463</section>
1464
1465<section title="302 Found" anchor="status.302">
1466  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1467  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1468<t>
1469   The target resource resides temporarily under a different URI.
1470   Since the redirection might be altered on occasion, the client &SHOULD;
1471   continue to use the effective request URI for future requests.
1472</t>
1473<t>
1474   The temporary URI &SHOULD; be given by the Location field in the
1475   response. Unless the request method was HEAD, the representation of the
1476   response &SHOULD; contain a short hypertext note with a hyperlink to
1477   the new URI(s).
1478</t>
1479<t>
1480   If the 302 status code is received in response to a request method
1481   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1482   then the request &MAY; be automatically redirected by the user agent without
1483   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1484   request unless it can be confirmed by the user, since this might
1485   change the conditions under which the request was issued.
1486</t>
1487<x:note>
1488  <t>
1489    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1490    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1491    specify that the client is not allowed to change the method on the
1492    redirected request.  However, most existing user agent implementations
1493    treat 302 as if it were a 303 response, performing a GET on the Location
1494    field-value regardless of the original request method. Therefore, a
1495    previous version of this specification
1496    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1497    status codes
1498    <xref target="status.303" format="none">303</xref> and
1499    <xref target="status.307" format="none">307</xref> for servers that wish
1500    to make unambiguously clear which kind of reaction is expected of the
1501    client.
1502  </t>
1503</x:note>
1504</section>
1505
1506<section title="303 See Other" anchor="status.303">
1507  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1508  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1509<t>
1510   The server directs the user agent to a different resource, indicated
1511   by a URI in the Location header field, that provides an indirect
1512   response to the original request.  The user agent &MAY; perform a GET
1513   request on the URI in the Location field in order to obtain a
1514   representation corresponding to the response, be redirected again,
1515   or end with an error status.  The Location URI is not a substitute
1516   reference for the effective request URI.
1517</t>
1518<t>
1519   The 303 status code is generally applicable to any HTTP method.  It is
1520   primarily used to allow the output of a POST action to redirect
1521   the user agent to a selected resource, since doing so provides the
1522   information corresponding to the POST response in a form that
1523   can be separately identified, bookmarked, and cached independent
1524   of the original request.
1525</t>
1526<t>
1527   A 303 response to a GET request indicates that the requested
1528   resource does not have a representation of its own that can be
1529   transferred by the server over HTTP.  The Location URI indicates a
1530   resource that is descriptive of the target resource, such that the
1531   follow-on representation might be useful to recipients without
1532   implying that it adequately represents the target resource.
1533   Note that answers to the questions of what can be represented, what
1534   representations are adequate, and what might be a useful description
1535   are outside the scope of HTTP and thus entirely determined by the
1536   URI owner(s).
1537</t>
1538<t>
1539   Except for responses to a HEAD request, the representation of a 303
1540   response &SHOULD; contain a short hypertext note with a hyperlink
1541   to the Location URI.
1542</t>
1543</section>
1544
1545<section title="304 Not Modified" anchor="status.304">
1546  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1547  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1548  <rdf:Description>
1549    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1550  </rdf:Description>
1551<t>
1552   The response to the request has not been modified since the conditions
1553   indicated by the client's conditional GET request, as defined in &status-304;.
1554</t>
1555</section>
1556
1557<section title="305 Use Proxy" anchor="status.305">
1558  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1559  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1560<t>
1561   The 305 status code was defined in a previous version of this specification
1562   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1563</t>
1564</section>
1565
1566<section title="306 (Unused)" anchor="status.306">
1567  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1568  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1569<t>
1570   The 306 status code was used in a previous version of the
1571   specification, is no longer used, and the code is reserved.
1572</t>
1573</section>
1574
1575<section title="307 Temporary Redirect" anchor="status.307">
1576  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1577  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1578<t>
1579   The target resource resides temporarily under a different URI.
1580   Since the redirection can change over time, the client &SHOULD;
1581   continue to use the effective request URI for future requests.
1582</t>
1583<t>
1584   The temporary URI &SHOULD; be given by the Location field in the
1585   response. Unless the request method was HEAD, the representation of the
1586   response &SHOULD; contain a short hypertext note with a hyperlink to
1587   the new URI(s), since many pre-HTTP/1.1 user agents do not
1588   understand the 307 status code. Therefore, the note &SHOULD; contain the
1589   information necessary for a user to repeat the original request on
1590   the new URI.
1591</t>
1592<t>
1593   If the 307 status code is received in response to a request method
1594   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1595   then the request &MAY; be automatically redirected by the user agent without
1596   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1597   request unless it can be confirmed by the user, since this might
1598   change the conditions under which the request was issued.
1599</t>
1600</section>
1601</section>
1602
1603<section title="Client Error 4xx" anchor="status.4xx">
1604<t>
1605   The 4xx class of status code is intended for cases in which the
1606   client seems to have erred. Except when responding to a HEAD request,
1607   the server &SHOULD; include a representation containing an explanation of the
1608   error situation, and whether it is a temporary or permanent
1609   condition. These status codes are applicable to any request method.
1610   User agents &SHOULD; display any included representation to the user.
1611</t>
1612<t>
1613   If the client is sending data, a server implementation using TCP
1614   &SHOULD; be careful to ensure that the client acknowledges receipt of
1615   the packet(s) containing the response, before the server closes the
1616   input connection. If the client continues sending data to the server
1617   after the close, the server's TCP stack will send a reset packet to
1618   the client, which might erase the client's unacknowledged input buffers
1619   before they can be read and interpreted by the HTTP application.
1620</t>
1621
1622<section title="400 Bad Request" anchor="status.400">
1623  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1624  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1625<t>
1626   The request could not be understood by the server due to malformed
1627   syntax. The client &SHOULD-NOT; repeat the request without
1628   modifications.
1629</t>
1630</section>
1631
1632<section title="401 Unauthorized" anchor="status.401">
1633  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1634  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1635  <rdf:Description>
1636    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part7</redirects-to>
1637  </rdf:Description>
1638<t>
1639   The request requires user authentication (see &status-401;).
1640</t>
1641</section>
1642
1643<section title="402 Payment Required" anchor="status.402">
1644  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1645  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1646<t>
1647   This code is reserved for future use.
1648</t>
1649</section>
1650
1651<section title="403 Forbidden" anchor="status.403">
1652  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1653  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1654<t>
1655   The server understood the request, but is refusing to fulfill it.
1656   Authorization will not help and the request &SHOULD-NOT;  be repeated.
1657   If the request method was not HEAD and the server wishes to make
1658   public why the request has not been fulfilled, it &SHOULD; describe the
1659   reason for the refusal in the representation.  If the server does not wish to
1660   make this information available to the client, the status code 404
1661   (Not Found) can be used instead.
1662</t>
1663</section>
1664
1665<section title="404 Not Found" anchor="status.404">
1666  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1667  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1668<t>
1669   The server has not found anything matching the effective request URI. No
1670   indication is given of whether the condition is temporary or
1671   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1672   knows, through some internally configurable mechanism, that an old
1673   resource is permanently unavailable and has no forwarding address.
1674   This status code is commonly used when the server does not wish to
1675   reveal exactly why the request has been refused, or when no other
1676   response is applicable.
1677</t>
1678</section>
1679
1680<section title="405 Method Not Allowed" anchor="status.405">
1681  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1682  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1683<t>
1684   The method specified in the Request-Line is not allowed for the target
1685   resource. The response &MUST; include an
1686   Allow header field containing a list of valid methods for the requested
1687   resource.
1688</t>
1689</section>
1690
1691<section title="406 Not Acceptable" anchor="status.406">
1692  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1693  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1694<t>
1695   The resource identified by the request is only capable of generating
1696   response representations which have content characteristics not acceptable
1697   according to the accept header fields sent in the request.
1698</t>
1699<t>
1700   Unless it was a HEAD request, the response &SHOULD; include a representation
1701   containing a list of available representation characteristics and location(s)
1702   from which the user or user agent can choose the one most
1703   appropriate. The data format is specified by the media type given
1704   in the Content-Type header field. Depending upon the format and the
1705   capabilities of the user agent, selection of the most appropriate
1706   choice &MAY; be performed automatically. However, this specification
1707   does not define any standard for such automatic selection.
1708</t>
1709<x:note>
1710  <t>
1711    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1712    not acceptable according to the accept header fields sent in the
1713    request. In some cases, this might even be preferable to sending a
1714    406 response. User agents are encouraged to inspect the header fields of
1715    an incoming response to determine if it is acceptable.
1716  </t>
1717</x:note>
1718<t>
1719   If the response could be unacceptable, a user agent &SHOULD;
1720   temporarily stop receipt of more data and query the user for a
1721   decision on further actions.
1722</t>
1723</section>
1724
1725<section title="407 Proxy Authentication Required" anchor="status.407">
1726  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1727  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1728<t>
1729   This code is similar to 401 (Unauthorized), but indicates that the
1730   client must first authenticate itself with the proxy (see &status-407;).
1731</t>
1732</section>
1733
1734<section title="408 Request Timeout" anchor="status.408">
1735  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1736  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1737<t>
1738   The client did not produce a request within the time that the server
1739   was prepared to wait. The client &MAY; repeat the request without
1740   modifications at any later time.
1741</t>
1742</section>
1743
1744<section title="409 Conflict" anchor="status.409">
1745  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1746  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1747<t>
1748   The request could not be completed due to a conflict with the current
1749   state of the resource. This code is only allowed in situations where
1750   it is expected that the user might be able to resolve the conflict
1751   and resubmit the request. The response body &SHOULD; include enough
1752   information for the user to recognize the source of the conflict.
1753   Ideally, the response representation would include enough information for the
1754   user or user agent to fix the problem; however, that might not be
1755   possible and is not required.
1756</t>
1757<t>
1758   Conflicts are most likely to occur in response to a PUT request. For
1759   example, if versioning were being used and the representation being PUT
1760   included changes to a resource which conflict with those made by an
1761   earlier (third-party) request, the server might use the 409 response
1762   to indicate that it can't complete the request. In this case, the
1763   response representation would likely contain a list of the differences
1764   between the two versions in a format defined by the response
1765   Content-Type.
1766</t>
1767</section>
1768
1769<section title="410 Gone" anchor="status.410">
1770  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1771  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1772<t>
1773   The target resource is no longer available at the server and no
1774   forwarding address is known. This condition is expected to be
1775   considered permanent. Clients with link editing capabilities &SHOULD;
1776   delete references to the effective request URI after user approval. If the
1777   server does not know, or has no facility to determine, whether or not
1778   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1779   used instead.
1780</t>
1781<t>
1782   The 410 response is primarily intended to assist the task of web
1783   maintenance by notifying the recipient that the resource is
1784   intentionally unavailable and that the server owners desire that
1785   remote links to that resource be removed. Such an event is common for
1786   limited-time, promotional services and for resources belonging to
1787   individuals no longer working at the server's site. It is not
1788   necessary to mark all permanently unavailable resources as "gone" or
1789   to keep the mark for any length of time -- that is left to the
1790   discretion of the server owner.
1791</t>
1792<t>
1793   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine freshness
1794   for 410 responses.
1795</t>
1796
1797</section>
1798
1799<section title="411 Length Required" anchor="status.411">
1800  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1801  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1802<t>
1803   The server refuses to accept the request without a defined Content-Length.
1804   The client &MAY; repeat the request if it adds a valid
1805   Content-Length header field containing the length of the message-body
1806   in the request message.
1807</t>
1808</section>
1809
1810<section title="412 Precondition Failed" anchor="status.412">
1811  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1812  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1813  <rdf:Description>
1814    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1815  </rdf:Description>
1816<t>
1817   The precondition given in one or more of the request-header fields
1818   evaluated to false when it was tested on the server, as defined in
1819   &status-412;.
1820</t>
1821</section>
1822
1823<section title="413 Request Entity Too Large" anchor="status.413">
1824  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1825  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1826<t>
1827   The server is refusing to process a request because the request
1828   representation is larger than the server is willing or able to process. The
1829   server &MAY; close the connection to prevent the client from continuing
1830   the request.
1831</t>
1832<t>
1833   If the condition is temporary, the server &SHOULD; include a Retry-After
1834   header field to indicate that it is temporary and after what
1835   time the client &MAY; try again.
1836</t>
1837</section>
1838
1839<section title="414 URI Too Long" anchor="status.414">
1840  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1841  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1842<t>
1843   The server is refusing to service the request because the effective request URI
1844   is longer than the server is willing to interpret. This rare
1845   condition is only likely to occur when a client has improperly
1846   converted a POST request to a GET request with long query
1847   information, when the client has descended into a URI "black hole" of
1848   redirection (e.g., a redirected URI prefix that points to a suffix of
1849   itself), or when the server is under attack by a client attempting to
1850   exploit security holes present in some servers using fixed-length
1851   buffers for reading or manipulating the effective request URI.
1852</t>
1853</section>
1854
1855<section title="415 Unsupported Media Type" anchor="status.415">
1856  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1857  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1858<t>
1859   The server is refusing to service the request because the representation of
1860   the request is in a format not supported by the target resource
1861   for the requested method.
1862</t>
1863</section>
1864
1865<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1866  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1867  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1868  <rdf:Description>
1869    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1870  </rdf:Description>
1871<t>
1872   The request included a Range request-header field (&header-range;) and none of
1873   the range-specifier values in this field overlap the current extent
1874   of the selected resource. See &status-416;.
1875</t>
1876</section>
1877
1878<section title="417 Expectation Failed" anchor="status.417">
1879  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
1880  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
1881<t>
1882   The expectation given in an Expect request-header field (see <xref target="header.expect"/>)
1883   could not be met by this server, or, if the server is a proxy,
1884   the server has unambiguous evidence that the request could not be met
1885   by the next-hop server.
1886</t>
1887</section>
1888</section>
1889
1890<section title="Server Error 5xx" anchor="status.5xx">
1891<t>
1892   Response status codes beginning with the digit "5" indicate cases in
1893   which the server is aware that it has erred or is incapable of
1894   performing the request. Except when responding to a HEAD request, the
1895   server &SHOULD; include a representation containing an explanation of the
1896   error situation, and whether it is a temporary or permanent
1897   condition. User agents &SHOULD; display any included representation to the
1898   user. These response codes are applicable to any request method.
1899</t>
1900
1901<section title="500 Internal Server Error" anchor="status.500">
1902  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
1903  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
1904<t>
1905   The server encountered an unexpected condition which prevented it
1906   from fulfilling the request.
1907</t>
1908</section>
1909
1910<section title="501 Not Implemented" anchor="status.501">
1911  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
1912  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
1913<t>
1914   The server does not support the functionality required to fulfill the
1915   request. This is the appropriate response when the server does not
1916   recognize the request method and is not capable of supporting it for
1917   any resource.
1918</t>
1919</section>
1920
1921<section title="502 Bad Gateway" anchor="status.502">
1922  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
1923  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
1924<t>
1925   The server, while acting as a gateway or proxy, received an invalid
1926   response from the upstream server it accessed in attempting to
1927   fulfill the request.
1928</t>
1929</section>
1930
1931<section title="503 Service Unavailable" anchor="status.503">
1932  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
1933  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
1934<t>
1935   The server is currently unable to handle the request due to a
1936   temporary overloading or maintenance of the server. The implication
1937   is that this is a temporary condition which will be alleviated after
1938   some delay. If known, the length of the delay &MAY; be indicated in a
1939   Retry-After header field. If no Retry-After is given, the client &SHOULD;
1940   handle the response as it would for a 500 response.
1941</t>
1942<x:note>
1943  <t>
1944    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
1945    server must use it when becoming overloaded. Some servers might wish
1946    to simply refuse the connection.
1947  </t>
1948</x:note>
1949</section>
1950
1951<section title="504 Gateway Timeout" anchor="status.504">
1952  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
1953  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
1954<t>
1955   The server, while acting as a gateway or proxy, did not receive a
1956   timely response from the upstream server specified by the URI (e.g.,
1957   HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
1958   to access in attempting to complete the request.
1959</t>
1960<x:note>
1961  <t>
1962    <x:h>Note</x:h> to implementors: some deployed proxies are known to
1963    return 400 or 500 when DNS lookups time out.
1964  </t>
1965</x:note>
1966</section>
1967
1968<section title="505 HTTP Version Not Supported" anchor="status.505">
1969  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
1970  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
1971<t>
1972   The server does not support, or refuses to support, the protocol
1973   version that was used in the request message. The server is
1974   indicating that it is unable or unwilling to complete the request
1975   using the same major version as the client, as described in &http-version;,
1976   other than with this error message. The response &SHOULD; contain
1977   a representation describing why that version is not supported and what other
1978   protocols are supported by that server.
1979</t>
1980
1981</section>
1982</section>
1983</section>
1984
1985
1986<section title="Header Field Definitions" anchor="header.fields">
1987<t>
1988   This section defines the syntax and semantics of HTTP/1.1 header fields
1989   related to request and response semantics.
1990</t>
1991
1992<section title="Allow" anchor="header.allow">
1993  <iref primary="true" item="Allow header" x:for-anchor=""/>
1994  <iref primary="true" item="Headers" subitem="Allow" x:for-anchor=""/>
1995  <x:anchor-alias value="Allow"/>
1996  <x:anchor-alias value="Allow-v"/>
1997<t>
1998   The "Allow" response-header field lists the set of methods advertised as
1999   supported by the target resource. The purpose of
2000   this field is strictly to inform the recipient of valid methods
2001   associated with the resource.
2002</t>
2003<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/><iref primary="true" item="Grammar" subitem="Allow-v"/>
2004  <x:ref>Allow</x:ref>   = "Allow" ":" <x:ref>OWS</x:ref> <x:ref>Allow-v</x:ref>
2005  <x:ref>Allow-v</x:ref> = #<x:ref>Method</x:ref>
2006</artwork></figure>
2007<t>
2008      Example of use:
2009</t>
2010<figure><artwork type="example">
2011  Allow: GET, HEAD, PUT
2012</artwork></figure>
2013<t>
2014      The actual set of allowed methods is defined
2015      by the origin server at the time of each request.
2016</t>
2017<t>
2018      A proxy &MUST-NOT; modify the Allow header field even if it does not
2019      understand all the methods specified, since the user agent might
2020      have other means of communicating with the origin server.
2021</t>
2022</section>
2023
2024<section title="Expect" anchor="header.expect">
2025  <iref primary="true" item="Expect header" x:for-anchor=""/>
2026  <iref primary="true" item="Headers" subitem="Expect" x:for-anchor=""/>
2027  <x:anchor-alias value="Expect"/>
2028  <x:anchor-alias value="Expect-v"/>
2029  <x:anchor-alias value="expectation"/>
2030  <x:anchor-alias value="expectation-extension"/>
2031  <x:anchor-alias value="expect-params"/>
2032<t>
2033   The "Expect" request-header field is used to indicate that particular
2034   server behaviors are required by the client.
2035</t>
2036<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"/>
2037  <x:ref>Expect</x:ref>       = "Expect" ":" <x:ref>OWS</x:ref> <x:ref>Expect-v</x:ref>
2038  <x:ref>Expect-v</x:ref>     = 1#<x:ref>expectation</x:ref>
2039 
2040  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
2041  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
2042                           *<x:ref>expect-params</x:ref> ]
2043  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
2044</artwork></figure>
2045<t>
2046   A server that does not understand or is unable to comply with any of
2047   the expectation values in the Expect field of a request &MUST; respond
2048   with appropriate error status code. The server &MUST; respond with a 417
2049   (Expectation Failed) status code if any of the expectations cannot be met
2050   or, if there are other problems with the request, some other 4xx
2051   status code.
2052</t>
2053<t>
2054   This header field is defined with extensible syntax to allow for
2055   future extensions. If a server receives a request containing an
2056   Expect field that includes an expectation-extension that it does not
2057   support, it &MUST; respond with a 417 (Expectation Failed) status code.
2058</t>
2059<t>
2060   Comparison of expectation values is case-insensitive for unquoted
2061   tokens (including the 100-continue token), and is case-sensitive for
2062   quoted-string expectation-extensions.
2063</t>
2064<t>
2065   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
2066   return a 417 (Expectation Failed) status code if it receives a request
2067   with an expectation that it cannot meet. However, the Expect
2068   request-header field itself is end-to-end; it &MUST; be forwarded if the
2069   request is forwarded.
2070</t>
2071<t>
2072   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
2073   Expect header field.
2074</t>
2075<t>
2076   See &use100; for the use of the 100 (Continue) status code.
2077</t>
2078</section>
2079
2080<section title="From" anchor="header.from">
2081  <iref primary="true" item="From header" x:for-anchor=""/>
2082  <iref primary="true" item="Headers" subitem="From" x:for-anchor=""/>
2083  <x:anchor-alias value="From"/>
2084  <x:anchor-alias value="From-v"/>
2085  <x:anchor-alias value="mailbox"/>
2086<t>
2087   The "From" request-header field, if given, &SHOULD; contain an Internet
2088   e-mail address for the human user who controls the requesting user
2089   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
2090   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
2091</t>
2092<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/><iref primary="true" item="Grammar" subitem="From-v"/>
2093  <x:ref>From</x:ref>    = "From" ":" <x:ref>OWS</x:ref> <x:ref>From-v</x:ref>
2094  <x:ref>From-v</x:ref>  = <x:ref>mailbox</x:ref>
2095 
2096  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
2097</artwork></figure>
2098<t>
2099   An example is:
2100</t>
2101<figure><artwork type="example">
2102  From: webmaster@example.org
2103</artwork></figure>
2104<t>
2105   This header field &MAY; be used for logging purposes and as a means for
2106   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
2107   be used as an insecure form of access protection. The interpretation
2108   of this field is that the request is being performed on behalf of the
2109   person given, who accepts responsibility for the method performed. In
2110   particular, robot agents &SHOULD; include this header field so that the
2111   person responsible for running the robot can be contacted if problems
2112   occur on the receiving end.
2113</t>
2114<t>
2115   The Internet e-mail address in this field &MAY; be separate from the
2116   Internet host which issued the request. For example, when a request
2117   is passed through a proxy the original issuer's address &SHOULD; be
2118   used.
2119</t>
2120<t>
2121   The client &SHOULD-NOT;  send the From header field without the user's
2122   approval, as it might conflict with the user's privacy interests or
2123   their site's security policy. It is strongly recommended that the
2124   user be able to disable, enable, and modify the value of this field
2125   at any time prior to a request.
2126</t>
2127</section>
2128
2129<section title="Location" anchor="header.location">
2130  <iref primary="true" item="Location header" x:for-anchor=""/>
2131  <iref primary="true" item="Headers" subitem="Location" x:for-anchor=""/>
2132  <x:anchor-alias value="Location"/>
2133  <x:anchor-alias value="Location-v"/>
2134<t>
2135   The "Location" response-header field is used to identify a newly created
2136   resource, or to redirect the recipient to a different location for
2137   completion of the request.
2138</t>
2139<t>
2140   For 201 (Created) responses, the Location is the URI of the new resource
2141   which was created by the request. For 3xx responses, the location &SHOULD;
2142   indicate the server's preferred URI for automatic redirection to the
2143   resource.
2144</t>
2145<t>
2146   The field value consists of a single URI-reference. When it has the form
2147   of a relative reference (<xref target="RFC3986" x:fmt="," x:sec="4.2"/>),
2148   the final value is computed by resolving it against the effective request
2149   URI (<xref target="RFC3986" x:fmt="," x:sec="5"/>).
2150</t>
2151<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/><iref primary="true" item="Grammar" subitem="Location-v"/>
2152  <x:ref>Location</x:ref>       = "Location" ":" <x:ref>OWS</x:ref> <x:ref>Location-v</x:ref>
2153  <x:ref>Location-v</x:ref>     = <x:ref>URI-reference</x:ref>
2154</artwork></figure>
2155<figure>
2156<preamble>Examples are:</preamble><!--DO NOT DARE changing the vertical WSP below, it's necessary this way for xml2rfc-->
2157<artwork type="example">
2158  Location: http://www.example.org/pub/WWW/People.html#tim
2159</artwork></figure><figure><artwork type="example">  Location: /index.html
2160</artwork></figure>
2161<t>
2162   There are circumstances in which a fragment identifier in a Location URI
2163   would not be appropriate:
2164   <list style="symbols">
2165      <t>With a 201 Created response, because in this usage the Location header
2166      field specifies the URI for the entire created resource.</t>
2167      <t>With 305 Use Proxy.</t>
2168   </list>
2169</t>
2170<x:note>
2171  <t>
2172    <x:h>Note:</x:h> This specification does not define precedence rules
2173    for the case where the original URI, as navigated to by the user
2174    agent, and the Location header field value both contain fragment
2175    identifiers.
2176  </t>
2177</x:note>
2178<x:note>
2179  <t>
2180    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2181    from Location in that the Content-Location identifies the most specific
2182    resource corresponding to the enclosed representation.
2183    It is therefore possible for a response to contain header fields for
2184    both Location and Content-Location.
2185  </t>
2186</x:note>
2187</section>
2188
2189<section title="Max-Forwards" anchor="header.max-forwards">
2190  <iref primary="true" item="Max-Forwards header" x:for-anchor=""/>
2191  <iref primary="true" item="Headers" subitem="Max-Forwards" x:for-anchor=""/>
2192  <x:anchor-alias value="Max-Forwards"/>
2193  <x:anchor-alias value="Max-Forwards-v"/>
2194<t>
2195   The "Max-Forwards" request-header field provides a mechanism with the
2196   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>)
2197   methods to limit the number of times that the request is forwarded by
2198   proxies or gateways. This can be useful when the client is attempting to
2199   trace a request which appears to be failing or looping in mid-chain.
2200</t>
2201<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/><iref primary="true" item="Grammar" subitem="Max-Forwards-v"/>
2202  <x:ref>Max-Forwards</x:ref>   = "Max-Forwards" ":" <x:ref>OWS</x:ref> <x:ref>Max-Forwards-v</x:ref>
2203  <x:ref>Max-Forwards-v</x:ref> = 1*<x:ref>DIGIT</x:ref>
2204</artwork></figure>
2205<t>
2206   The Max-Forwards value is a decimal integer indicating the remaining
2207   number of times this request message can be forwarded.
2208</t>
2209<t>
2210   Each proxy or gateway recipient of a TRACE or OPTIONS request
2211   containing a Max-Forwards header field &MUST; check and update its
2212   value prior to forwarding the request. If the received value is zero
2213   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2214   respond as the final recipient. If the received Max-Forwards value is
2215   greater than zero, then the forwarded message &MUST; contain an updated
2216   Max-Forwards field with a value decremented by one (1).
2217</t>
2218<t>
2219   The Max-Forwards header field &MAY; be ignored for all other methods
2220   defined by this specification and for any extension methods for which
2221   it is not explicitly referred to as part of that method definition.
2222</t>
2223</section>
2224
2225<section title="Referer" anchor="header.referer">
2226  <iref primary="true" item="Referer header" x:for-anchor=""/>
2227  <iref primary="true" item="Headers" subitem="Referer" x:for-anchor=""/>
2228  <x:anchor-alias value="Referer"/>
2229  <x:anchor-alias value="Referer-v"/>
2230<t>
2231   The "Referer" [sic] request-header field allows the client to specify the
2232   URI of the resource from which the effective request URI was obtained (the
2233   "referrer", although the header field is misspelled.).
2234</t>
2235<t>
2236   The Referer header field allows servers to generate lists of back-links to
2237   resources for interest, logging, optimized caching, etc. It also allows
2238   obsolete or mistyped links to be traced for maintenance. Some servers use
2239   Referer as a means of controlling where they allow links from (so-called
2240   "deep linking"), but legitimate requests do not always
2241   contain a Referer header field.
2242</t>
2243<t>
2244   If the effective request URI was obtained from a source that does not have its own
2245   URI (e.g., input from the user keyboard), the Referer field &MUST; either be
2246   sent with the value "about:blank", or not be sent at all. Note that this
2247   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2248</t>
2249<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/><iref primary="true" item="Grammar" subitem="Referer-v"/>
2250  <x:ref>Referer</x:ref>        = "Referer" ":" <x:ref>OWS</x:ref> <x:ref>Referer-v</x:ref>
2251  <x:ref>Referer-v</x:ref>      = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2252</artwork></figure>
2253<t>
2254   Example:
2255</t>
2256<figure><artwork type="example">
2257  Referer: http://www.example.org/hypertext/Overview.html
2258</artwork></figure>
2259<t>
2260   If the field value is a relative URI, it &SHOULD; be interpreted
2261   relative to the effective request URI. The URI &MUST-NOT; include a fragment. See
2262   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2263</t>
2264</section>
2265
2266<section title="Retry-After" anchor="header.retry-after">
2267  <iref primary="true" item="Retry-After header" x:for-anchor=""/>
2268  <iref primary="true" item="Headers" subitem="Retry-After" x:for-anchor=""/>
2269  <x:anchor-alias value="Retry-After"/>
2270  <x:anchor-alias value="Retry-After-v"/>
2271<t>
2272   The response-header "Retry-After" field can be used with a 503 (Service
2273   Unavailable) response to indicate how long the service is expected to
2274   be unavailable to the requesting client. This field &MAY; also be used
2275   with any 3xx (Redirection) response to indicate the minimum time the
2276   user-agent is asked wait before issuing the redirected request.
2277</t>
2278<t>
2279   The value of this field can be either an HTTP-date or an integer number
2280   of seconds (in decimal) after the time of the response.
2281</t>
2282<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/><iref primary="true" item="Grammar" subitem="Retry-After-v"/>
2283  <x:ref>Retry-After</x:ref>   = "Retry-After" ":" <x:ref>OWS</x:ref> <x:ref>Retry-After-v</x:ref>
2284  <x:ref>Retry-After-v</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2285</artwork></figure>
2286<t anchor="rule.delta-seconds">
2287  <x:anchor-alias value="delta-seconds"/>
2288   Time spans are non-negative decimal integers, representing time in
2289   seconds.
2290</t>
2291<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2292  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2293</artwork></figure>
2294<t>
2295   Two examples of its use are
2296</t>
2297<figure><artwork type="example">
2298  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2299  Retry-After: 120
2300</artwork></figure>
2301<t>
2302   In the latter example, the delay is 2 minutes.
2303</t>
2304</section>
2305
2306<section title="Server" anchor="header.server">
2307  <iref primary="true" item="Server header" x:for-anchor=""/>
2308  <iref primary="true" item="Headers" subitem="Server" x:for-anchor=""/>
2309  <x:anchor-alias value="Server"/>
2310  <x:anchor-alias value="Server-v"/>
2311<t>
2312   The "Server" response-header field contains information about the
2313   software used by the origin server to handle the request.
2314</t>
2315<t>
2316   The field can contain multiple product tokens (&product-tokens;) and
2317   comments (&header-fields;) identifying the server and any significant
2318   subproducts. The product tokens are listed in order of their significance
2319   for identifying the application.
2320</t>
2321<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/><iref primary="true" item="Grammar" subitem="Server-v"/>
2322  <x:ref>Server</x:ref>         = "Server" ":" <x:ref>OWS</x:ref> <x:ref>Server-v</x:ref>
2323  <x:ref>Server-v</x:ref>       = <x:ref>product</x:ref>
2324                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2325</artwork></figure>
2326<t>
2327   Example:
2328</t>
2329<figure><artwork type="example">
2330  Server: CERN/3.0 libwww/2.17
2331</artwork></figure>
2332<t>
2333   If the response is being forwarded through a proxy, the proxy
2334   application &MUST-NOT; modify the Server response-header field. Instead, it
2335   &MUST; include a Via field (as described in &header-via;).
2336</t>
2337<x:note>
2338  <t>
2339    <x:h>Note:</x:h> Revealing the specific software version of the server might
2340    allow the server machine to become more vulnerable to attacks
2341    against software that is known to contain security holes. Server
2342    implementors are encouraged to make this field a configurable
2343    option.
2344  </t>
2345</x:note>
2346</section>
2347
2348<section title="User-Agent" anchor="header.user-agent">
2349  <iref primary="true" item="User-Agent header" x:for-anchor=""/>
2350  <iref primary="true" item="Headers" subitem="User-Agent" x:for-anchor=""/>
2351  <x:anchor-alias value="User-Agent"/>
2352  <x:anchor-alias value="User-Agent-v"/>
2353<t>
2354   The "User-Agent" request-header field contains information about the user
2355   agent originating the request. User agents &SHOULD; include this field with
2356   requests.
2357</t>
2358<t>
2359   Typically, it is used for statistical purposes, the tracing of protocol
2360   violations, and tailoring responses to avoid particular user agent
2361   limitations.
2362</t>
2363<t>
2364   The field can contain multiple product tokens (&product-tokens;)
2365   and comments (&header-fields;) identifying the agent and its
2366   significant subproducts. By convention, the product tokens are listed in
2367   order of their significance for identifying the application.
2368</t>
2369<t>
2370   Because this field is usually sent on every request a user agent makes,
2371   implementations are encouraged not to include needlessly fine-grained
2372   detail, and to limit (or even prohibit) the addition of subproducts by third
2373   parties. Overly long and detailed User-Agent field values make requests
2374   larger and can also be used to identify ("fingerprint") the user against
2375   their wishes.
2376</t>
2377<t>
2378   Likewise, implementations are encouraged not to use the product tokens of
2379   other implementations in order to declare compatibility with them, as this
2380   circumvents the purpose of the field. Finally, they are encouraged not to
2381   use comments to identify products; doing so makes the field value more
2382   difficult to parse.
2383</t>
2384<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/><iref primary="true" item="Grammar" subitem="User-Agent-v"/>
2385  <x:ref>User-Agent</x:ref>     = "User-Agent" ":" <x:ref>OWS</x:ref> <x:ref>User-Agent-v</x:ref>
2386  <x:ref>User-Agent-v</x:ref>   = <x:ref>product</x:ref>
2387                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2388</artwork></figure>
2389<t>
2390   Example:
2391</t>
2392<figure><artwork type="example">
2393  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2394</artwork></figure>
2395</section>
2396
2397</section>
2398
2399<section title="IANA Considerations" anchor="IANA.considerations">
2400
2401<section title="Method Registry" anchor="method.registration">
2402<t>
2403  The registration procedure for HTTP Methods is defined by
2404  <xref target="method.registry"/> of this document.
2405</t>
2406<t>
2407   The HTTP Method Registry shall be created at <eref target="http://www.iana.org/assignments/http-methods"/>
2408   and be populated with the registrations below:
2409</t>
2410<?BEGININC p2-semantics.iana-methods ?>
2411<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2412<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2413   <ttcol>Method</ttcol>
2414   <ttcol>Safe</ttcol>
2415   <ttcol>Reference</ttcol>
2416   <c>CONNECT</c>
2417   <c>no</c>
2418   <c>
2419      <xref target="CONNECT"/>
2420   </c>
2421   <c>DELETE</c>
2422   <c>no</c>
2423   <c>
2424      <xref target="DELETE"/>
2425   </c>
2426   <c>GET</c>
2427   <c>yes</c>
2428   <c>
2429      <xref target="GET"/>
2430   </c>
2431   <c>HEAD</c>
2432   <c>yes</c>
2433   <c>
2434      <xref target="HEAD"/>
2435   </c>
2436   <c>OPTIONS</c>
2437   <c>yes</c>
2438   <c>
2439      <xref target="OPTIONS"/>
2440   </c>
2441   <c>POST</c>
2442   <c>no</c>
2443   <c>
2444      <xref target="POST"/>
2445   </c>
2446   <c>PUT</c>
2447   <c>no</c>
2448   <c>
2449      <xref target="PUT"/>
2450   </c>
2451   <c>TRACE</c>
2452   <c>yes</c>
2453   <c>
2454      <xref target="TRACE"/>
2455   </c>
2456</texttable>
2457<!--(END)-->
2458<?ENDINC p2-semantics.iana-methods ?>
2459</section>
2460
2461<section title="Status Code Registry" anchor="status.code.registration">
2462<t>
2463   The registration procedure for HTTP Status Codes -- previously defined
2464   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> -- is now defined
2465   by <xref target="status.code.registry"/> of this document.
2466</t>
2467<t>
2468   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2469   shall be updated with the registrations below:
2470</t>
2471<?BEGININC p2-semantics.iana-status-codes ?>
2472<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2473<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2474   <ttcol>Value</ttcol>
2475   <ttcol>Description</ttcol>
2476   <ttcol>Reference</ttcol>
2477   <c>100</c>
2478   <c>Continue</c>
2479   <c>
2480      <xref target="status.100"/>
2481   </c>
2482   <c>101</c>
2483   <c>Switching Protocols</c>
2484   <c>
2485      <xref target="status.101"/>
2486   </c>
2487   <c>200</c>
2488   <c>OK</c>
2489   <c>
2490      <xref target="status.200"/>
2491   </c>
2492   <c>201</c>
2493   <c>Created</c>
2494   <c>
2495      <xref target="status.201"/>
2496   </c>
2497   <c>202</c>
2498   <c>Accepted</c>
2499   <c>
2500      <xref target="status.202"/>
2501   </c>
2502   <c>203</c>
2503   <c>Non-Authoritative Information</c>
2504   <c>
2505      <xref target="status.203"/>
2506   </c>
2507   <c>204</c>
2508   <c>No Content</c>
2509   <c>
2510      <xref target="status.204"/>
2511   </c>
2512   <c>205</c>
2513   <c>Reset Content</c>
2514   <c>
2515      <xref target="status.205"/>
2516   </c>
2517   <c>300</c>
2518   <c>Multiple Choices</c>
2519   <c>
2520      <xref target="status.300"/>
2521   </c>
2522   <c>301</c>
2523   <c>Moved Permanently</c>
2524   <c>
2525      <xref target="status.301"/>
2526   </c>
2527   <c>302</c>
2528   <c>Found</c>
2529   <c>
2530      <xref target="status.302"/>
2531   </c>
2532   <c>303</c>
2533   <c>See Other</c>
2534   <c>
2535      <xref target="status.303"/>
2536   </c>
2537   <c>305</c>
2538   <c>Use Proxy</c>
2539   <c>
2540      <xref target="status.305"/>
2541   </c>
2542   <c>306</c>
2543   <c>(Unused)</c>
2544   <c>
2545      <xref target="status.306"/>
2546   </c>
2547   <c>307</c>
2548   <c>Temporary Redirect</c>
2549   <c>
2550      <xref target="status.307"/>
2551   </c>
2552   <c>400</c>
2553   <c>Bad Request</c>
2554   <c>
2555      <xref target="status.400"/>
2556   </c>
2557   <c>402</c>
2558   <c>Payment Required</c>
2559   <c>
2560      <xref target="status.402"/>
2561   </c>
2562   <c>403</c>
2563   <c>Forbidden</c>
2564   <c>
2565      <xref target="status.403"/>
2566   </c>
2567   <c>404</c>
2568   <c>Not Found</c>
2569   <c>
2570      <xref target="status.404"/>
2571   </c>
2572   <c>405</c>
2573   <c>Method Not Allowed</c>
2574   <c>
2575      <xref target="status.405"/>
2576   </c>
2577   <c>406</c>
2578   <c>Not Acceptable</c>
2579   <c>
2580      <xref target="status.406"/>
2581   </c>
2582   <c>407</c>
2583   <c>Proxy Authentication Required</c>
2584   <c>
2585      <xref target="status.407"/>
2586   </c>
2587   <c>408</c>
2588   <c>Request Timeout</c>
2589   <c>
2590      <xref target="status.408"/>
2591   </c>
2592   <c>409</c>
2593   <c>Conflict</c>
2594   <c>
2595      <xref target="status.409"/>
2596   </c>
2597   <c>410</c>
2598   <c>Gone</c>
2599   <c>
2600      <xref target="status.410"/>
2601   </c>
2602   <c>411</c>
2603   <c>Length Required</c>
2604   <c>
2605      <xref target="status.411"/>
2606   </c>
2607   <c>413</c>
2608   <c>Request Entity Too Large</c>
2609   <c>
2610      <xref target="status.413"/>
2611   </c>
2612   <c>414</c>
2613   <c>URI Too Long</c>
2614   <c>
2615      <xref target="status.414"/>
2616   </c>
2617   <c>415</c>
2618   <c>Unsupported Media Type</c>
2619   <c>
2620      <xref target="status.415"/>
2621   </c>
2622   <c>417</c>
2623   <c>Expectation Failed</c>
2624   <c>
2625      <xref target="status.417"/>
2626   </c>
2627   <c>500</c>
2628   <c>Internal Server Error</c>
2629   <c>
2630      <xref target="status.500"/>
2631   </c>
2632   <c>501</c>
2633   <c>Not Implemented</c>
2634   <c>
2635      <xref target="status.501"/>
2636   </c>
2637   <c>502</c>
2638   <c>Bad Gateway</c>
2639   <c>
2640      <xref target="status.502"/>
2641   </c>
2642   <c>503</c>
2643   <c>Service Unavailable</c>
2644   <c>
2645      <xref target="status.503"/>
2646   </c>
2647   <c>504</c>
2648   <c>Gateway Timeout</c>
2649   <c>
2650      <xref target="status.504"/>
2651   </c>
2652   <c>505</c>
2653   <c>HTTP Version Not Supported</c>
2654   <c>
2655      <xref target="status.505"/>
2656   </c>
2657</texttable>
2658<!--(END)-->
2659<?ENDINC p2-semantics.iana-status-codes ?>
2660</section>
2661<section title="Header Field Registration" anchor="header.field.registration">
2662<t>
2663   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
2664   with the permanent registrations below (see <xref target="RFC3864"/>):
2665</t>
2666<?BEGININC p2-semantics.iana-headers ?>
2667<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2668<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2669   <ttcol>Header Field Name</ttcol>
2670   <ttcol>Protocol</ttcol>
2671   <ttcol>Status</ttcol>
2672   <ttcol>Reference</ttcol>
2673
2674   <c>Allow</c>
2675   <c>http</c>
2676   <c>standard</c>
2677   <c>
2678      <xref target="header.allow"/>
2679   </c>
2680   <c>Expect</c>
2681   <c>http</c>
2682   <c>standard</c>
2683   <c>
2684      <xref target="header.expect"/>
2685   </c>
2686   <c>From</c>
2687   <c>http</c>
2688   <c>standard</c>
2689   <c>
2690      <xref target="header.from"/>
2691   </c>
2692   <c>Location</c>
2693   <c>http</c>
2694   <c>standard</c>
2695   <c>
2696      <xref target="header.location"/>
2697   </c>
2698   <c>Max-Forwards</c>
2699   <c>http</c>
2700   <c>standard</c>
2701   <c>
2702      <xref target="header.max-forwards"/>
2703   </c>
2704   <c>Referer</c>
2705   <c>http</c>
2706   <c>standard</c>
2707   <c>
2708      <xref target="header.referer"/>
2709   </c>
2710   <c>Retry-After</c>
2711   <c>http</c>
2712   <c>standard</c>
2713   <c>
2714      <xref target="header.retry-after"/>
2715   </c>
2716   <c>Server</c>
2717   <c>http</c>
2718   <c>standard</c>
2719   <c>
2720      <xref target="header.server"/>
2721   </c>
2722   <c>User-Agent</c>
2723   <c>http</c>
2724   <c>standard</c>
2725   <c>
2726      <xref target="header.user-agent"/>
2727   </c>
2728</texttable>
2729<!--(END)-->
2730<?ENDINC p2-semantics.iana-headers ?>
2731<t>
2732   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2733</t>
2734</section>
2735</section>
2736
2737<section title="Security Considerations" anchor="security.considerations">
2738<t>
2739   This section is meant to inform application developers, information
2740   providers, and users of the security limitations in HTTP/1.1 as
2741   described by this document. The discussion does not include
2742   definitive solutions to the problems revealed, though it does make
2743   some suggestions for reducing security risks.
2744</t>
2745
2746<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2747<t>
2748   Like any generic data transfer protocol, HTTP cannot regulate the
2749   content of the data that is transferred, nor is there any a priori
2750   method of determining the sensitivity of any particular piece of
2751   information within the context of any given request. Therefore,
2752   applications &SHOULD; supply as much control over this information as
2753   possible to the provider of that information. Four header fields are
2754   worth special mention in this context: Server, Via, Referer and From.
2755</t>
2756<t>
2757   Revealing the specific software version of the server might allow the
2758   server machine to become more vulnerable to attacks against software
2759   that is known to contain security holes. Implementors &SHOULD; make the
2760   Server header field a configurable option.
2761</t>
2762<t>
2763   Proxies which serve as a portal through a network firewall &SHOULD;
2764   take special precautions regarding the transfer of header information
2765   that identifies the hosts behind the firewall. In particular, they
2766   &SHOULD; remove, or replace with sanitized versions, any Via fields
2767   generated behind the firewall.
2768</t>
2769<t>
2770   The Referer header field allows reading patterns to be studied and reverse
2771   links drawn. Although it can be very useful, its power can be abused
2772   if user details are not separated from the information contained in
2773   the Referer. Even when the personal information has been removed, the
2774   Referer header field might indicate a private document's URI whose
2775   publication would be inappropriate.
2776</t>
2777<t>
2778   The information sent in the From field might conflict with the user's
2779   privacy interests or their site's security policy, and hence it
2780   &SHOULD-NOT;  be transmitted without the user being able to disable,
2781   enable, and modify the contents of the field. The user &MUST; be able
2782   to set the contents of this field within a user preference or
2783   application defaults configuration.
2784</t>
2785<t>
2786   We suggest, though do not require, that a convenient toggle interface
2787   be provided for the user to enable or disable the sending of From and
2788   Referer information.
2789</t>
2790<t>
2791   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref
2792   target="header.server"/>) header fields can sometimes be used to determine
2793   that a specific client or server have a particular security hole which might
2794   be exploited. Unfortunately, this same information is often used for other
2795   valuable purposes for which HTTP currently has no better mechanism.
2796</t>
2797<t>
2798   Furthermore, the User-Agent header field may contain enough entropy to be
2799   used, possibly in conjunction with other material, to uniquely identify the
2800   user.
2801</t>
2802<t>
2803   Some methods, like TRACE (<xref target="TRACE"/>), expose information
2804   that was sent in request header fields within the body of their response.
2805   Clients &SHOULD; be careful with sensitive information, like Cookies,
2806   Authorization credentials and other header fields that might be used to
2807   collect data from the client.
2808</t> 
2809</section>
2810
2811<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2812<t>
2813   Because the source of a link might be private information or might
2814   reveal an otherwise private information source, it is strongly
2815   recommended that the user be able to select whether or not the
2816   Referer field is sent. For example, a browser client could have a
2817   toggle switch for browsing openly/anonymously, which would
2818   respectively enable/disable the sending of Referer and From
2819   information.
2820</t>
2821<t>
2822   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2823   HTTP request if the referring page was transferred with a secure
2824   protocol.
2825</t>
2826<t>
2827   Authors of services &SHOULD-NOT; use GET-based forms for the submission of
2828   sensitive data because that data will be placed in the request-target. Many
2829   existing servers, proxies, and user agents log or display the request-target
2830   in places where it might be visible to third parties. Such services can
2831   use POST-based form submission instead.
2832</t>
2833</section>
2834
2835<section title="Location Headers and Spoofing" anchor="location.spoofing">
2836<t>
2837   If a single server supports multiple organizations that do not trust
2838   one another, then it &MUST; check the values of Location and Content-Location
2839   header fields in responses that are generated under control of
2840   said organizations to make sure that they do not attempt to
2841   invalidate resources over which they have no authority.
2842</t>
2843</section>
2844
2845</section>
2846
2847<section title="Acknowledgments" anchor="ack">
2848</section>
2849</middle>
2850<back>
2851
2852<references title="Normative References">
2853
2854<reference anchor="Part1">
2855  <front>
2856    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2857    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2858      <organization abbrev="Day Software">Day Software</organization>
2859      <address><email>fielding@gbiv.com</email></address>
2860    </author>
2861    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2862      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2863      <address><email>jg@freedesktop.org</email></address>
2864    </author>
2865    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2866      <organization abbrev="HP">Hewlett-Packard Company</organization>
2867      <address><email>JeffMogul@acm.org</email></address>
2868    </author>
2869    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2870      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2871      <address><email>henrikn@microsoft.com</email></address>
2872    </author>
2873    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2874      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2875      <address><email>LMM@acm.org</email></address>
2876    </author>
2877    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2878      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2879      <address><email>paulle@microsoft.com</email></address>
2880    </author>
2881    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2882      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2883      <address><email>timbl@w3.org</email></address>
2884    </author>
2885    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2886      <organization abbrev="W3C">World Wide Web Consortium</organization>
2887      <address><email>ylafon@w3.org</email></address>
2888    </author>
2889    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2890      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2891      <address><email>julian.reschke@greenbytes.de</email></address>
2892    </author>
2893    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2894  </front>
2895  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
2896  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
2897</reference>
2898
2899<reference anchor="Part3">
2900  <front>
2901    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
2902    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2903      <organization abbrev="Day Software">Day Software</organization>
2904      <address><email>fielding@gbiv.com</email></address>
2905    </author>
2906    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2907      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2908      <address><email>jg@freedesktop.org</email></address>
2909    </author>
2910    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2911      <organization abbrev="HP">Hewlett-Packard Company</organization>
2912      <address><email>JeffMogul@acm.org</email></address>
2913    </author>
2914    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2915      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2916      <address><email>henrikn@microsoft.com</email></address>
2917    </author>
2918    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2919      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2920      <address><email>LMM@acm.org</email></address>
2921    </author>
2922    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2923      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2924      <address><email>paulle@microsoft.com</email></address>
2925    </author>
2926    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2927      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2928      <address><email>timbl@w3.org</email></address>
2929    </author>
2930    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2931      <organization abbrev="W3C">World Wide Web Consortium</organization>
2932      <address><email>ylafon@w3.org</email></address>
2933    </author>
2934    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2935      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2936      <address><email>julian.reschke@greenbytes.de</email></address>
2937    </author>
2938    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2939  </front>
2940  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
2941  <x:source href="p3-payload.xml" basename="p3-payload"/>
2942</reference>
2943
2944<reference anchor="Part4">
2945  <front>
2946    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
2947    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2948      <organization abbrev="Day Software">Day Software</organization>
2949      <address><email>fielding@gbiv.com</email></address>
2950    </author>
2951    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2952      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2953      <address><email>jg@freedesktop.org</email></address>
2954    </author>
2955    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2956      <organization abbrev="HP">Hewlett-Packard Company</organization>
2957      <address><email>JeffMogul@acm.org</email></address>
2958    </author>
2959    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2960      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2961      <address><email>henrikn@microsoft.com</email></address>
2962    </author>
2963    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2964      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2965      <address><email>LMM@acm.org</email></address>
2966    </author>
2967    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2968      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2969      <address><email>paulle@microsoft.com</email></address>
2970    </author>
2971    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2972      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2973      <address><email>timbl@w3.org</email></address>
2974    </author>
2975    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2976      <organization abbrev="W3C">World Wide Web Consortium</organization>
2977      <address><email>ylafon@w3.org</email></address>
2978    </author>
2979    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2980      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2981      <address><email>julian.reschke@greenbytes.de</email></address>
2982    </author>
2983    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2984  </front>
2985  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
2986  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
2987</reference>
2988
2989<reference anchor="Part5">
2990  <front>
2991    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
2992    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2993      <organization abbrev="Day Software">Day Software</organization>
2994      <address><email>fielding@gbiv.com</email></address>
2995    </author>
2996    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2997      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2998      <address><email>jg@freedesktop.org</email></address>
2999    </author>
3000    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3001      <organization abbrev="HP">Hewlett-Packard Company</organization>
3002      <address><email>JeffMogul@acm.org</email></address>
3003    </author>
3004    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3005      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3006      <address><email>henrikn@microsoft.com</email></address>
3007    </author>
3008    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3009      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3010      <address><email>LMM@acm.org</email></address>
3011    </author>
3012    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3013      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3014      <address><email>paulle@microsoft.com</email></address>
3015    </author>
3016    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3017      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3018      <address><email>timbl@w3.org</email></address>
3019    </author>
3020    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3021      <organization abbrev="W3C">World Wide Web Consortium</organization>
3022      <address><email>ylafon@w3.org</email></address>
3023    </author>
3024    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3025      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3026      <address><email>julian.reschke@greenbytes.de</email></address>
3027    </author>
3028    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3029  </front>
3030  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
3031  <x:source href="p5-range.xml" basename="p5-range"/>
3032</reference>
3033
3034<reference anchor="Part6">
3035  <front>
3036    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
3037    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3038      <organization abbrev="Day Software">Day Software</organization>
3039      <address><email>fielding@gbiv.com</email></address>
3040    </author>
3041    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3042      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3043      <address><email>jg@freedesktop.org</email></address>
3044    </author>
3045    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3046      <organization abbrev="HP">Hewlett-Packard Company</organization>
3047      <address><email>JeffMogul@acm.org</email></address>
3048    </author>
3049    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3050      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3051      <address><email>henrikn@microsoft.com</email></address>
3052    </author>
3053    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3054      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3055      <address><email>LMM@acm.org</email></address>
3056    </author>
3057    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3058      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3059      <address><email>paulle@microsoft.com</email></address>
3060    </author>
3061    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3062      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3063      <address><email>timbl@w3.org</email></address>
3064    </author>
3065    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3066      <organization abbrev="W3C">World Wide Web Consortium</organization>
3067      <address><email>ylafon@w3.org</email></address>
3068    </author>
3069    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
3070      <address><email>mnot@mnot.net</email></address>
3071    </author>
3072    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3073      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3074      <address><email>julian.reschke@greenbytes.de</email></address>
3075    </author>
3076    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3077  </front>
3078  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
3079  <x:source href="p6-cache.xml" basename="p6-cache"/>
3080</reference>
3081
3082<reference anchor="Part7">
3083  <front>
3084    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
3085    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3086      <organization abbrev="Day Software">Day Software</organization>
3087      <address><email>fielding@gbiv.com</email></address>
3088    </author>
3089    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3090      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3091      <address><email>jg@freedesktop.org</email></address>
3092    </author>
3093    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3094      <organization abbrev="HP">Hewlett-Packard Company</organization>
3095      <address><email>JeffMogul@acm.org</email></address>
3096    </author>
3097    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3098      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3099      <address><email>henrikn@microsoft.com</email></address>
3100    </author>
3101    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3102      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3103      <address><email>LMM@acm.org</email></address>
3104    </author>
3105    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3106      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3107      <address><email>paulle@microsoft.com</email></address>
3108    </author>
3109    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3110      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3111      <address><email>timbl@w3.org</email></address>
3112    </author>
3113    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3114      <organization abbrev="W3C">World Wide Web Consortium</organization>
3115      <address><email>ylafon@w3.org</email></address>
3116    </author>
3117    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3118      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3119      <address><email>julian.reschke@greenbytes.de</email></address>
3120    </author>
3121    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3122  </front>
3123  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
3124  <x:source href="p7-auth.xml" basename="p7-auth"/>
3125</reference>
3126
3127<reference anchor="RFC2119">
3128  <front>
3129    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
3130    <author initials="S." surname="Bradner" fullname="Scott Bradner">
3131      <organization>Harvard University</organization>
3132      <address><email>sob@harvard.edu</email></address>
3133    </author>
3134    <date month="March" year="1997"/>
3135  </front>
3136  <seriesInfo name="BCP" value="14"/>
3137  <seriesInfo name="RFC" value="2119"/>
3138</reference>
3139
3140<reference anchor="RFC3986">
3141 <front>
3142  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
3143  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
3144    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3145    <address>
3146       <email>timbl@w3.org</email>
3147       <uri>http://www.w3.org/People/Berners-Lee/</uri>
3148    </address>
3149  </author>
3150  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
3151    <organization abbrev="Day Software">Day Software</organization>
3152    <address>
3153      <email>fielding@gbiv.com</email>
3154      <uri>http://roy.gbiv.com/</uri>
3155    </address>
3156  </author>
3157  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
3158    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
3159    <address>
3160      <email>LMM@acm.org</email>
3161      <uri>http://larry.masinter.net/</uri>
3162    </address>
3163  </author>
3164  <date month='January' year='2005'></date>
3165 </front>
3166 <seriesInfo name="STD" value="66"/>
3167 <seriesInfo name="RFC" value="3986"/>
3168</reference>
3169
3170<reference anchor="RFC5234">
3171  <front>
3172    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
3173    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3174      <organization>Brandenburg InternetWorking</organization>
3175      <address>
3176        <email>dcrocker@bbiw.net</email>
3177      </address> 
3178    </author>
3179    <author initials="P." surname="Overell" fullname="Paul Overell">
3180      <organization>THUS plc.</organization>
3181      <address>
3182        <email>paul.overell@thus.net</email>
3183      </address>
3184    </author>
3185    <date month="January" year="2008"/>
3186  </front>
3187  <seriesInfo name="STD" value="68"/>
3188  <seriesInfo name="RFC" value="5234"/>
3189</reference>
3190
3191</references>
3192
3193<references title="Informative References">
3194
3195<reference anchor="RFC1945">
3196  <front>
3197    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3198    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3199      <organization>MIT, Laboratory for Computer Science</organization>
3200      <address><email>timbl@w3.org</email></address>
3201    </author>
3202    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3203      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3204      <address><email>fielding@ics.uci.edu</email></address>
3205    </author>
3206    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3207      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3208      <address><email>frystyk@w3.org</email></address>
3209    </author>
3210    <date month="May" year="1996"/>
3211  </front>
3212  <seriesInfo name="RFC" value="1945"/>
3213</reference>
3214
3215<reference anchor="RFC2068">
3216  <front>
3217    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3218    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3219      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3220      <address><email>fielding@ics.uci.edu</email></address>
3221    </author>
3222    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3223      <organization>MIT Laboratory for Computer Science</organization>
3224      <address><email>jg@w3.org</email></address>
3225    </author>
3226    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3227      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3228      <address><email>mogul@wrl.dec.com</email></address>
3229    </author>
3230    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3231      <organization>MIT Laboratory for Computer Science</organization>
3232      <address><email>frystyk@w3.org</email></address>
3233    </author>
3234    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3235      <organization>MIT Laboratory for Computer Science</organization>
3236      <address><email>timbl@w3.org</email></address>
3237    </author>
3238    <date month="January" year="1997"/>
3239  </front>
3240  <seriesInfo name="RFC" value="2068"/>
3241</reference>
3242
3243<reference anchor="RFC2616">
3244  <front>
3245    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3246    <author initials="R." surname="Fielding" fullname="R. Fielding">
3247      <organization>University of California, Irvine</organization>
3248      <address><email>fielding@ics.uci.edu</email></address>
3249    </author>
3250    <author initials="J." surname="Gettys" fullname="J. Gettys">
3251      <organization>W3C</organization>
3252      <address><email>jg@w3.org</email></address>
3253    </author>
3254    <author initials="J." surname="Mogul" fullname="J. Mogul">
3255      <organization>Compaq Computer Corporation</organization>
3256      <address><email>mogul@wrl.dec.com</email></address>
3257    </author>
3258    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3259      <organization>MIT Laboratory for Computer Science</organization>
3260      <address><email>frystyk@w3.org</email></address>
3261    </author>
3262    <author initials="L." surname="Masinter" fullname="L. Masinter">
3263      <organization>Xerox Corporation</organization>
3264      <address><email>masinter@parc.xerox.com</email></address>
3265    </author>
3266    <author initials="P." surname="Leach" fullname="P. Leach">
3267      <organization>Microsoft Corporation</organization>
3268      <address><email>paulle@microsoft.com</email></address>
3269    </author>
3270    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3271      <organization>W3C</organization>
3272      <address><email>timbl@w3.org</email></address>
3273    </author>
3274    <date month="June" year="1999"/>
3275  </front>
3276  <seriesInfo name="RFC" value="2616"/>
3277</reference>
3278
3279<reference anchor='RFC2817'>
3280  <front>
3281    <title>Upgrading to TLS Within HTTP/1.1</title>
3282    <author initials='R.' surname='Khare' fullname='R. Khare'>
3283      <organization>4K Associates / UC Irvine</organization>
3284      <address><email>rohit@4K-associates.com</email></address>
3285    </author>
3286    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3287      <organization>Agranat Systems, Inc.</organization>
3288      <address><email>lawrence@agranat.com</email></address>
3289    </author>
3290    <date year='2000' month='May' />
3291  </front>
3292  <seriesInfo name='RFC' value='2817' />
3293</reference>
3294
3295<reference anchor='RFC3864'>
3296  <front>
3297    <title>Registration Procedures for Message Header Fields</title>
3298    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3299      <organization>Nine by Nine</organization>
3300      <address><email>GK-IETF@ninebynine.org</email></address>
3301    </author>
3302    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3303      <organization>BEA Systems</organization>
3304      <address><email>mnot@pobox.com</email></address>
3305    </author>
3306    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3307      <organization>HP Labs</organization>
3308      <address><email>JeffMogul@acm.org</email></address>
3309    </author>
3310    <date year='2004' month='September' />
3311  </front>
3312  <seriesInfo name='BCP' value='90' />
3313  <seriesInfo name='RFC' value='3864' />
3314</reference>
3315
3316<reference anchor='RFC5226'>
3317  <front>
3318    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3319    <author initials='T.' surname='Narten' fullname='T. Narten'>
3320      <organization>IBM</organization>
3321      <address><email>narten@us.ibm.com</email></address>
3322    </author>
3323    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3324      <organization>Google</organization>
3325      <address><email>Harald@Alvestrand.no</email></address>
3326    </author>
3327    <date year='2008' month='May' />
3328  </front>
3329  <seriesInfo name='BCP' value='26' />
3330  <seriesInfo name='RFC' value='5226' />
3331</reference>
3332
3333<reference anchor="RFC5322">
3334  <front>
3335    <title>Internet Message Format</title>
3336    <author initials="P." surname="Resnick" fullname="P. Resnick">
3337      <organization>Qualcomm Incorporated</organization>
3338    </author>
3339    <date year="2008" month="October"/>
3340  </front> 
3341  <seriesInfo name="RFC" value="5322"/>
3342</reference>
3343
3344</references>
3345
3346<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3347<t>
3348  This document takes over the Status Code Registry, previously defined
3349  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3350  (<xref target="status.code.registry"/>)
3351</t>
3352<t>
3353  Clarify definition of POST.
3354  (<xref target="POST"/>)
3355</t>
3356<t>
3357  Failed to consider that there are
3358  many other request methods that are safe to automatically redirect,
3359  and further that the user agent is able to make that determination
3360  based on the request method semantics.
3361  (Sections <xref format="counter" target="status.301"/>,
3362  <xref format="counter" target="status.302"/> and
3363  <xref format="counter" target="status.307"/>)
3364</t>
3365<t>
3366  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3367  It used to indicate that the target resource must be accessed through the
3368  proxy given by the Location field. The Location field gave the URI of the
3369  proxy. The recipient was expected to repeat this single request via the proxy.
3370  (<xref target="status.305"/>)
3371</t>
3372<t>
3373  Reclassify "Allow" as response header field, removing the option to
3374  specify it in a PUT request.
3375  Relax the server requirement on the contents of the Allow header field and
3376  remove requirement on clients to always trust the header field value.
3377  (<xref target="header.allow"/>)
3378</t>
3379<t>
3380  Correct syntax of Location header field to allow URI references (including
3381  relative references and fragments), as referred symbol "absoluteURI" wasn't
3382  what was expected, and add some clarifications as to when use of fragments
3383  would not be appropriate.
3384  (<xref target="header.location"/>)
3385</t>
3386<t>
3387  Allow Referer field value of "about:blank" as alternative to not specifying it.
3388  (<xref target="header.referer"/>)
3389</t>
3390<t>
3391  In the description of the Server header field, the Via field
3392  was described as a SHOULD. The requirement was and is stated
3393  correctly in the description of the Via header field in &header-via;.
3394  (<xref target="header.server"/>)
3395</t>
3396</section>
3397
3398<?BEGININC p2-semantics.abnf-appendix ?>
3399<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3400<figure>
3401<artwork type="abnf" name="p2-semantics.parsed-abnf">
3402<x:ref>Accept</x:ref> = &lt;Accept, defined in [Part3], Section 6.1&gt;
3403<x:ref>Accept-Charset</x:ref> = &lt;Accept-Charset, defined in [Part3], Section 6.2&gt;
3404<x:ref>Accept-Encoding</x:ref> = &lt;Accept-Encoding, defined in [Part3], Section 6.3&gt;
3405<x:ref>Accept-Language</x:ref> = &lt;Accept-Language, defined in [Part3], Section 6.4&gt;
3406<x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in [Part5], Section 5.1&gt;
3407<x:ref>Age</x:ref> = &lt;Age, defined in [Part6], Section 3.1&gt;
3408<x:ref>Allow</x:ref> = "Allow:" OWS Allow-v
3409<x:ref>Allow-v</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3410<x:ref>Authorization</x:ref> = &lt;Authorization, defined in [Part7], Section 4.1&gt;
3411
3412<x:ref>ETag</x:ref> = &lt;ETag, defined in [Part4], Section 6.1&gt;
3413<x:ref>Expect</x:ref> = "Expect:" OWS Expect-v
3414<x:ref>Expect-v</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3415
3416<x:ref>From</x:ref> = "From:" OWS From-v
3417<x:ref>From-v</x:ref> = mailbox
3418
3419<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3420<x:ref>Host</x:ref> = &lt;Host, defined in [Part1], Section 2.6&gt;
3421
3422<x:ref>If-Match</x:ref> = &lt;If-Match, defined in [Part4], Section 6.2&gt;
3423If-Modified-Since =
3424 &lt;If-Modified-Since, defined in [Part4], Section 6.3&gt;
3425<x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in [Part4], Section 6.4&gt;
3426<x:ref>If-Range</x:ref> = &lt;If-Range, defined in [Part5], Section 5.3&gt;
3427If-Unmodified-Since =
3428 &lt;If-Unmodified-Since, defined in [Part4], Section 6.5&gt;
3429
3430<x:ref>Location</x:ref> = "Location:" OWS Location-v
3431<x:ref>Location-v</x:ref> = URI-reference
3432
3433<x:ref>Max-Forwards</x:ref> = "Max-Forwards:" OWS Max-Forwards-v
3434<x:ref>Max-Forwards-v</x:ref> = 1*DIGIT
3435<x:ref>Method</x:ref> = %x4F.50.54.49.4F.4E.53 ; OPTIONS
3436 / %x47.45.54 ; GET
3437 / %x48.45.41.44 ; HEAD
3438 / %x50.4F.53.54 ; POST
3439 / %x50.55.54 ; PUT
3440 / %x44.45.4C.45.54.45 ; DELETE
3441 / %x54.52.41.43.45 ; TRACE
3442 / %x43.4F.4E.4E.45.43.54 ; CONNECT
3443 / extension-method
3444
3445<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3446
3447Proxy-Authenticate =
3448 &lt;Proxy-Authenticate, defined in [Part7], Section 4.2&gt;
3449Proxy-Authorization =
3450 &lt;Proxy-Authorization, defined in [Part7], Section 4.3&gt;
3451
3452<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3453<x:ref>Range</x:ref> = &lt;Range, defined in [Part5], Section 5.4&gt;
3454<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3455<x:ref>Referer</x:ref> = "Referer:" OWS Referer-v
3456<x:ref>Referer-v</x:ref> = absolute-URI / partial-URI
3457<x:ref>Retry-After</x:ref> = "Retry-After:" OWS Retry-After-v
3458<x:ref>Retry-After-v</x:ref> = HTTP-date / delta-seconds
3459
3460<x:ref>Server</x:ref> = "Server:" OWS Server-v
3461<x:ref>Server-v</x:ref> = product *( RWS ( product / comment ) )
3462<x:ref>Status-Code</x:ref> = "100" / "101" / "200" / "201" / "202" / "203" / "204" /
3463 "205" / "206" / "300" / "301" / "302" / "303" / "304" / "305" /
3464 "307" / "400" / "401" / "402" / "403" / "404" / "405" / "406" /
3465 "407" / "408" / "409" / "410" / "411" / "412" / "413" / "414" /
3466 "415" / "416" / "417" / "500" / "501" / "502" / "503" / "504" /
3467 "505" / extension-code
3468
3469<x:ref>TE</x:ref> = &lt;TE, defined in [Part1], Section 9.5&gt;
3470
3471<x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in [Part1], Section 2.6&gt;
3472<x:ref>User-Agent</x:ref> = "User-Agent:" OWS User-Agent-v
3473<x:ref>User-Agent-v</x:ref> = product *( RWS ( product / comment ) )
3474
3475<x:ref>Vary</x:ref> = &lt;Vary, defined in [Part6], Section 3.5&gt;
3476
3477WWW-Authenticate =
3478 &lt;WWW-Authenticate, defined in [Part7], Section 4.4&gt;
3479
3480<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
3481
3482<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3483
3484<x:ref>delta-seconds</x:ref> = 1*DIGIT
3485
3486<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3487<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3488<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3489 *expect-params ]
3490<x:ref>extension-code</x:ref> = 3DIGIT
3491<x:ref>extension-method</x:ref> = token
3492
3493<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3494
3495<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3496
3497<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
3498<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3499
3500<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3501
3502<x:ref>request-header</x:ref> = Accept / Accept-Charset / Accept-Encoding /
3503 Accept-Language / Authorization / Expect / From / Host / If-Match /
3504 If-Modified-Since / If-None-Match / If-Range / If-Unmodified-Since /
3505 Max-Forwards / Proxy-Authorization / Range / Referer / TE /
3506 User-Agent
3507<x:ref>response-header</x:ref> = Accept-Ranges / Age / Allow / ETag / Location /
3508 Proxy-Authenticate / Retry-After / Server / Vary / WWW-Authenticate
3509
3510<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3511</artwork>
3512</figure>
3513<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3514; Reason-Phrase defined but not used
3515; Status-Code defined but not used
3516; request-header defined but not used
3517; response-header defined but not used
3518</artwork></figure></section>
3519<?ENDINC p2-semantics.abnf-appendix ?>
3520
3521<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3522
3523<section title="Since RFC 2616">
3524<t>
3525  Extracted relevant partitions from <xref target="RFC2616"/>.
3526</t>
3527</section>
3528
3529<section title="Since draft-ietf-httpbis-p2-semantics-00">
3530<t>
3531  Closed issues:
3532  <list style="symbols"> 
3533    <t>
3534      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3535      "Via is a MUST"
3536      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3537    </t>
3538    <t>
3539      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3540      "Fragments allowed in Location"
3541      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3542    </t>
3543    <t>
3544      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3545      "Safe Methods vs Redirection"
3546      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3547    </t>
3548    <t>
3549      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3550      "Revise description of the POST method"
3551      (<eref target="http://purl.org/NET/http-errata#post"/>)
3552    </t>
3553    <t>
3554      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3555      "Normative and Informative references"
3556    </t>
3557    <t>
3558      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3559      "RFC2606 Compliance"
3560    </t>
3561    <t>
3562      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3563      "Informative references"
3564    </t>
3565    <t>
3566      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3567      "Redundant cross-references"
3568    </t>
3569  </list>
3570</t>
3571<t>
3572  Other changes:
3573  <list style="symbols"> 
3574    <t>
3575      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3576    </t>
3577  </list>
3578</t>
3579</section>
3580
3581<section title="Since draft-ietf-httpbis-p2-semantics-01">
3582<t>
3583  Closed issues:
3584  <list style="symbols"> 
3585    <t>
3586      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3587      "PUT side effects"
3588    </t>
3589    <t>
3590      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3591      "Duplicate Host header requirements"
3592    </t>
3593  </list>
3594</t>
3595<t>
3596  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3597  <list style="symbols"> 
3598    <t>
3599      Move "Product Tokens" section (back) into Part 1, as "token" is used
3600      in the definition of the Upgrade header field.
3601    </t>
3602    <t>
3603      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3604    </t>
3605    <t>
3606      Copy definition of delta-seconds from Part6 instead of referencing it.
3607    </t>
3608  </list>
3609</t>
3610</section>
3611
3612<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3613<t>
3614  Closed issues:
3615  <list style="symbols"> 
3616    <t>
3617      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3618      "Requiring Allow in 405 responses"
3619    </t>
3620    <t>
3621      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3622      "Status Code Registry"
3623    </t>
3624    <t>
3625      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3626      "Redirection vs. Location"
3627    </t>
3628    <t>
3629      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3630      "Cacheability of 303 response"
3631    </t>
3632    <t>
3633      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3634      "305 Use Proxy"
3635    </t>
3636    <t>
3637      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3638      "Classification for Allow header"
3639    </t>
3640    <t>
3641      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3642      "PUT - 'store under' vs 'store at'"
3643    </t>
3644  </list>
3645</t>
3646<t>
3647  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3648  <list style="symbols"> 
3649    <t>
3650      Reference RFC 3984, and update header field registrations for headers defined
3651      in this document.
3652    </t>
3653  </list>
3654</t>
3655<t>
3656  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3657  <list style="symbols"> 
3658    <t>
3659      Replace string literals when the string really is case-sensitive (method).
3660    </t>
3661  </list>
3662</t>
3663</section>
3664
3665<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3666<t>
3667  Closed issues:
3668  <list style="symbols"> 
3669    <t>
3670      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3671      "OPTIONS request bodies"
3672    </t>
3673    <t>
3674      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3675      "Description of CONNECT should refer to RFC2817"
3676    </t>
3677    <t>
3678      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3679      "Location Content-Location reference request/response mixup"
3680    </t>
3681  </list>
3682</t>
3683<t>
3684  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3685  <list style="symbols"> 
3686    <t>
3687      Added initial proposal for registration process, plus initial
3688      content (non-HTTP/1.1 methods to be added by a separate specification).
3689    </t>
3690  </list>
3691</t>
3692</section>
3693
3694<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3695<t>
3696  Closed issues:
3697  <list style="symbols"> 
3698    <t>
3699      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3700      "Content-*"
3701    </t>
3702    <t>
3703      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3704      "RFC 2822 is updated by RFC 5322"
3705    </t>
3706  </list>
3707</t>
3708<t>
3709  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3710  <list style="symbols"> 
3711    <t>
3712      Use "/" instead of "|" for alternatives.
3713    </t>
3714    <t>
3715      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3716      whitespace ("OWS") and required whitespace ("RWS").
3717    </t>
3718    <t>
3719      Rewrite ABNFs to spell out whitespace rules, factor out
3720      header field value format definitions.
3721    </t>
3722  </list>
3723</t>
3724</section>
3725
3726<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3727<t>
3728  Closed issues:
3729  <list style="symbols"> 
3730    <t>
3731      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3732      "Reason-Phrase BNF"
3733    </t>
3734  </list>
3735</t>
3736<t>
3737  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3738  <list style="symbols"> 
3739    <t>
3740      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3741    </t>
3742  </list>
3743</t>
3744</section>
3745
3746<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3747<t>
3748  Closed issues:
3749  <list style="symbols"> 
3750    <t>
3751      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3752      "Clarify when Referer is sent"
3753    </t>
3754    <t>
3755      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3756      "status codes vs methods"
3757    </t>
3758    <t>
3759      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3760      "Do not require "updates" relation for specs that register status codes or method names"
3761    </t>
3762  </list>
3763</t>
3764</section>
3765
3766<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3767<t>
3768  Closed issues:
3769  <list style="symbols"> 
3770    <t>
3771      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3772      "Idempotency"
3773    </t>
3774    <t>
3775      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3776      "TRACE security considerations"
3777    </t>
3778    <t>
3779      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3780      "Clarify rules for determining what entities a response carries"
3781    </t>
3782    <t>
3783      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3784      "update note citing RFC 1945 and 2068"
3785    </t>
3786    <t>
3787      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3788      "update note about redirect limit"
3789    </t>
3790    <t>
3791      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3792      "Location header ABNF should use 'URI'"
3793    </t>
3794    <t>
3795      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3796      "fragments in Location vs status 303"
3797    </t>
3798    <t>
3799      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
3800      "move IANA registrations for optional status codes"
3801    </t>
3802  </list>
3803</t>
3804<t>
3805  Partly resolved issues:
3806  <list style="symbols"> 
3807    <t>
3808      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/171"/>:
3809      "Are OPTIONS and TRACE safe?"
3810    </t>
3811  </list>
3812</t>
3813</section>
3814
3815<section title="Since draft-ietf-httpbis-p2-semantics-08" anchor="changes.since.08">
3816<t>
3817  Closed issues:
3818  <list style="symbols"> 
3819    <t>
3820      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3821      "Safe Methods vs Redirection" (we missed the introduction to the 3xx
3822      status codes when fixing this previously)
3823    </t>
3824  </list>
3825</t>
3826</section>
3827
3828<section title="Since draft-ietf-httpbis-p2-semantics-09" anchor="changes.since.09">
3829<t>
3830  Closed issues:
3831  <list style="symbols"> 
3832    <t>
3833      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
3834      "Fragment combination / precedence during redirects"
3835    </t>
3836  </list>
3837</t>
3838<t>
3839  Partly resolved issues:
3840  <list style="symbols"> 
3841    <t>
3842      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/185"/>:
3843      "Location header payload handling"
3844    </t>
3845    <t>
3846      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
3847      "Term for the requested resource's URI"
3848    </t>
3849  </list>
3850</t>
3851</section>
3852
3853<section title="Since draft-ietf-httpbis-p2-semantics-10" anchor="changes.since.10">
3854<t>
3855  Closed issues:
3856  <list style="symbols"> 
3857    <t>
3858      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
3859      "Clarify 'Requested Variant'"
3860    </t>
3861    <t>
3862      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
3863      "Clarify entity / representation / variant terminology"
3864    </t>
3865    <t>
3866      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/139"/>:
3867      "Methods and Caching"
3868    </t>
3869    <t>
3870      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/190"/>:
3871      "OPTIONS vs Max-Forwards"
3872    </t>
3873    <t>
3874      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/199"/>:
3875      "Status codes and caching"
3876    </t>
3877    <t>
3878      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
3879      "consider removing the 'changes from 2068' sections"
3880    </t>
3881  </list>
3882</t>
3883</section>
3884
3885<section title="Since draft-ietf-httpbis-p2-semantics-11" anchor="changes.since.11">
3886<t>
3887  Closed issues:
3888  <list style="symbols"> 
3889    <t>
3890      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/229"/>:
3891      "Considerations for new status codes"
3892    </t>
3893    <t>
3894      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/230"/>:
3895      "Considerations for new methods"
3896    </t>
3897    <t>
3898      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/232"/>:
3899      "User-Agent guidelines" (relating to the 'User-Agent' header field)
3900    </t>
3901  </list>
3902</t>
3903</section>
3904
3905</section>
3906
3907</back>
3908</rfc>
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