source: draft-ietf-httpbis/latest/p3-payload.xml @ 1267

Last change on this file since 1267 was 1267, checked in by julian.reschke@…, 9 years ago

Remove Content-MD5 (see #178)

  • Property svn:eol-style set to native
File size: 122.1 KB
Line 
1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "April">
16  <!ENTITY ID-YEAR "2011">
17  <!ENTITY mdash "&#8212;">
18  <!ENTITY notation                 "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY notation-abnf            "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY basic-rules              "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY caching-neg-resp         "<xref target='Part6' x:rel='#caching.negotiated.responses' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY header-transfer-encoding "<xref target='Part1' x:rel='#header.transfer-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY header-content-length    "<xref target='Part1' x:rel='#header.content-length' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY header-content-range     "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY header-expires           "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY header-last-modified     "<xref target='Part4' x:rel='#header.last-modified' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY header-user-agent        "<xref target='Part2' x:rel='#header.user-agent' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY header-vary              "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY message-body             "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY multipart-byteranges     "<xref target='Part5' x:rel='#internet.media.type.multipart.byteranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY full-date                "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY qvalue                   "<xref target='Part1' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY uri                      "<xref target='Part1' x:rel='#uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY effective-request-uri    "<xref target='Part1' x:rel='#effective.request.uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35  <!ENTITY compression-codings      "<xref target='Part1' x:rel='#compression.codings' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY transfer-codings         "<xref target='Part1' x:rel='#transfer.codings' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY compress-coding          "<xref target='Part1' x:rel='#compress.coding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY deflate-coding           "<xref target='Part1' x:rel='#deflate.coding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY gzip-coding              "<xref target='Part1' x:rel='#gzip.coding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY response-representation  "<xref target='Part2' x:rel='#identifying.response.associated.with.representation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41]>
42<?rfc toc="yes" ?>
43<?rfc symrefs="yes" ?>
44<?rfc sortrefs="yes" ?>
45<?rfc compact="yes"?>
46<?rfc subcompact="no" ?>
47<?rfc linkmailto="no" ?>
48<?rfc editing="no" ?>
49<?rfc comments="yes"?>
50<?rfc inline="yes"?>
51<?rfc rfcedstyle="yes"?>
52<?rfc-ext allow-markup-in-artwork="yes" ?>
53<?rfc-ext include-references-in-index="yes" ?>
54<rfc obsoletes="2616" category="std" x:maturity-level="draft"
55     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p3-payload-&ID-VERSION;"
56     xmlns:x='http://purl.org/net/xml2rfc/ext'>
57<front>
58
59  <title abbrev="HTTP/1.1, Part 3">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
60
61  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
62    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
63    <address>
64      <postal>
65        <street>345 Park Ave</street>
66        <city>San Jose</city>
67        <region>CA</region>
68        <code>95110</code>
69        <country>USA</country>
70      </postal>
71      <email>fielding@gbiv.com</email>
72      <uri>http://roy.gbiv.com/</uri>
73    </address>
74  </author>
75
76  <author initials="J." surname="Gettys" fullname="Jim Gettys">
77    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
78    <address>
79      <postal>
80        <street>21 Oak Knoll Road</street>
81        <city>Carlisle</city>
82        <region>MA</region>
83        <code>01741</code>
84        <country>USA</country>
85      </postal>
86      <email>jg@freedesktop.org</email>
87      <uri>http://gettys.wordpress.com/</uri>
88    </address>
89  </author>
90 
91  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
92    <organization abbrev="HP">Hewlett-Packard Company</organization>
93    <address>
94      <postal>
95        <street>HP Labs, Large Scale Systems Group</street>
96        <street>1501 Page Mill Road, MS 1177</street>
97        <city>Palo Alto</city>
98        <region>CA</region>
99        <code>94304</code>
100        <country>USA</country>
101      </postal>
102      <email>JeffMogul@acm.org</email>
103    </address>
104  </author>
105
106  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
107    <organization abbrev="Microsoft">Microsoft Corporation</organization>
108    <address>
109      <postal>
110        <street>1 Microsoft Way</street>
111        <city>Redmond</city>
112        <region>WA</region>
113        <code>98052</code>
114        <country>USA</country>
115      </postal>
116      <email>henrikn@microsoft.com</email>
117    </address>
118  </author>
119
120  <author initials="L." surname="Masinter" fullname="Larry Masinter">
121    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
122    <address>
123      <postal>
124        <street>345 Park Ave</street>
125        <city>San Jose</city>
126        <region>CA</region>
127        <code>95110</code>
128        <country>USA</country>
129      </postal>
130      <email>LMM@acm.org</email>
131      <uri>http://larry.masinter.net/</uri>
132    </address>
133  </author>
134 
135  <author initials="P." surname="Leach" fullname="Paul J. Leach">
136    <organization abbrev="Microsoft">Microsoft Corporation</organization>
137    <address>
138      <postal>
139        <street>1 Microsoft Way</street>
140        <city>Redmond</city>
141        <region>WA</region>
142        <code>98052</code>
143      </postal>
144      <email>paulle@microsoft.com</email>
145    </address>
146  </author>
147   
148  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
149    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
150    <address>
151      <postal>
152        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
153        <street>The Stata Center, Building 32</street>
154        <street>32 Vassar Street</street>
155        <city>Cambridge</city>
156        <region>MA</region>
157        <code>02139</code>
158        <country>USA</country>
159      </postal>
160      <email>timbl@w3.org</email>
161      <uri>http://www.w3.org/People/Berners-Lee/</uri>
162    </address>
163  </author>
164
165  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
166    <organization abbrev="W3C">World Wide Web Consortium</organization>
167    <address>
168      <postal>
169        <street>W3C / ERCIM</street>
170        <street>2004, rte des Lucioles</street>
171        <city>Sophia-Antipolis</city>
172        <region>AM</region>
173        <code>06902</code>
174        <country>France</country>
175      </postal>
176      <email>ylafon@w3.org</email>
177      <uri>http://www.raubacapeu.net/people/yves/</uri>
178    </address>
179  </author>
180
181  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
182    <organization abbrev="greenbytes">greenbytes GmbH</organization>
183    <address>
184      <postal>
185        <street>Hafenweg 16</street>
186        <city>Muenster</city><region>NW</region><code>48155</code>
187        <country>Germany</country>
188      </postal>
189      <phone>+49 251 2807760</phone>
190      <facsimile>+49 251 2807761</facsimile>
191      <email>julian.reschke@greenbytes.de</email>
192      <uri>http://greenbytes.de/tech/webdav/</uri>
193    </address>
194  </author>
195
196  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
197  <workgroup>HTTPbis Working Group</workgroup>
198
199<abstract>
200<t>
201   The Hypertext Transfer Protocol (HTTP) is an application-level
202   protocol for distributed, collaborative, hypermedia information
203   systems. HTTP has been in use by the World Wide Web global information
204   initiative since 1990. This document is Part 3 of the seven-part specification
205   that defines the protocol referred to as "HTTP/1.1" and, taken together,
206   obsoletes RFC 2616.  Part 3 defines HTTP message content,
207   metadata, and content negotiation.
208</t>
209</abstract>
210
211<note title="Editorial Note (To be removed by RFC Editor)">
212  <t>
213    Discussion of this draft should take place on the HTTPBIS working group
214    mailing list (ietf-http-wg@w3.org). The current issues list is
215    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/>
216    and related documents (including fancy diffs) can be found at
217    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
218  </t>
219  <t>
220    The changes in this draft are summarized in <xref target="changes.since.13"/>.
221  </t>
222</note>
223</front>
224<middle>
225<section title="Introduction" anchor="introduction">
226<t>
227   This document defines HTTP/1.1 message payloads (a.k.a., content), the
228   associated metadata header fields that define how the payload is intended
229   to be interpreted by a recipient, the request header fields that
230   might influence content selection, and the various selection algorithms
231   that are collectively referred to as HTTP content negotiation.
232</t>
233<t>
234   This document is currently disorganized in order to minimize the changes
235   between drafts and enable reviewers to see the smaller errata changes.
236   A future draft will reorganize the sections to better reflect the content.
237   In particular, the sections on entities will be renamed payload and moved
238   to the first half of the document, while the sections on content negotiation
239   and associated request header fields will be moved to the second half.  The
240   current mess reflects how widely dispersed these topics and associated
241   requirements had become in <xref target="RFC2616"/>.
242</t>
243
244<section title="Terminology" anchor="terminology">
245<t>
246   This specification uses a number of terms to refer to the roles
247   played by participants in, and objects of, the HTTP communication.
248</t>
249<t>
250  <iref item="content negotiation"/>
251  <x:dfn>content negotiation</x:dfn>
252  <list>
253    <t>
254      The mechanism for selecting the appropriate representation when
255      servicing a request. The representation in any response
256      can be negotiated (including error responses).
257    </t>
258  </list>
259</t>
260</section>
261
262<section title="Requirements" anchor="intro.requirements">
263<t>
264   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
265   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
266   document are to be interpreted as described in <xref target="RFC2119"/>.
267</t>
268<t>
269   An implementation is not compliant if it fails to satisfy one or more
270   of the "MUST" or "REQUIRED" level requirements for the protocols it
271   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
272   level and all the "SHOULD" level requirements for its protocols is said
273   to be "unconditionally compliant"; one that satisfies all the "MUST"
274   level requirements but not all the "SHOULD" level requirements for its
275   protocols is said to be "conditionally compliant".
276</t>
277</section>
278
279<section title="Syntax Notation" anchor="notation">
280  <x:anchor-alias value="ALPHA"/>
281  <x:anchor-alias value="CR"/>
282  <x:anchor-alias value="DIGIT"/>
283  <x:anchor-alias value="LF"/>
284  <x:anchor-alias value="OCTET"/>
285  <x:anchor-alias value="VCHAR"/>
286  <x:anchor-alias value="WSP"/>
287<t>
288  This specification uses the ABNF syntax defined in &notation; (which
289  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
290  <xref target="collected.abnf"/> shows the collected ABNF, with the list
291  rule expanded.
292</t>
293<t>
294  The following core rules are included by
295  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
296  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
297  DIGIT (decimal 0-9), DQUOTE (double quote),
298  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
299  OCTET (any 8-bit sequence of data), SP (space),
300  VCHAR (any visible USASCII character),
301  and WSP (whitespace).
302</t>
303
304<section title="Core Rules" anchor="core.rules">
305  <x:anchor-alias value="token"/>
306  <x:anchor-alias value="word"/>
307  <x:anchor-alias value="OWS"/>
308<t>
309  The core rules below are defined in &basic-rules;:
310</t>
311<figure><artwork type="abnf2616">
312  <x:ref>token</x:ref>          = &lt;token, defined in &basic-rules;&gt;
313  <x:ref>word</x:ref>           = &lt;word, defined in &basic-rules;&gt;
314  <x:ref>OWS</x:ref>            = &lt;OWS, defined in &basic-rules;&gt;
315</artwork></figure>
316</section>
317
318<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
319  <x:anchor-alias value="absolute-URI"/>
320  <x:anchor-alias value="partial-URI"/>
321  <x:anchor-alias value="qvalue"/>
322<t>
323  The ABNF rules below are defined in other parts:
324</t>
325<figure><!--Part1--><artwork type="abnf2616">
326  <x:ref>absolute-URI</x:ref>   = &lt;absolute-URI, defined in &uri;&gt;
327  <x:ref>partial-URI</x:ref>    = &lt;partial-URI, defined in &uri;&gt;
328  <x:ref>qvalue</x:ref>         = &lt;qvalue, defined in &qvalue;&gt;
329</artwork></figure>
330</section>
331
332</section>
333
334</section>
335
336<section title="Protocol Parameters" anchor="protocol.parameters">
337
338<section title="Character Encodings (charset)" anchor="character.sets">
339<t>
340   HTTP uses charset names to indicate the character encoding of a
341   textual representation.
342</t>
343<t anchor="rule.charset">
344  <x:anchor-alias value="charset"/>
345   A character encoding is identified by a case-insensitive token. The
346   complete set of tokens is defined by the IANA Character Set registry
347   (<eref target="http://www.iana.org/assignments/character-sets"/>).
348</t>
349<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="charset"/>
350  <x:ref>charset</x:ref> = <x:ref>token</x:ref>
351</artwork></figure>
352<t>
353   Although HTTP allows an arbitrary token to be used as a charset
354   value, any token that has a predefined value within the IANA
355   Character Set registry &MUST; represent the character encoding defined
356   by that registry. Applications &SHOULD; limit their use of character
357   encodings to those defined within the IANA registry.
358</t>
359<t>
360   HTTP uses charset in two contexts: within an Accept-Charset request
361   header field (in which the charset value is an unquoted token) and as the
362   value of a parameter in a Content-Type header field (within a request or
363   response), in which case the parameter value of the charset parameter
364   can be quoted.
365</t>
366<t>
367   Implementors need to be aware of IETF character set requirements <xref target="RFC3629"/>
368   <xref target="RFC2277"/>.
369</t>
370</section>
371
372<section title="Content Codings" anchor="content.codings">
373  <x:anchor-alias value="content-coding"/>
374<t>
375   Content coding values indicate an encoding transformation that has
376   been or can be applied to a representation. Content codings are primarily
377   used to allow a representation to be compressed or otherwise usefully
378   transformed without losing the identity of its underlying media type
379   and without loss of information. Frequently, the representation is stored in
380   coded form, transmitted directly, and only decoded by the recipient.
381</t>
382<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="content-coding"/>
383  <x:ref>content-coding</x:ref>   = <x:ref>token</x:ref>
384</artwork></figure>
385<t>
386   All content-coding values are case-insensitive. HTTP/1.1 uses
387   content-coding values in the Accept-Encoding (<xref target="header.accept-encoding"/>) and
388   Content-Encoding (<xref target="header.content-encoding"/>) header fields. Although the value
389   describes the content-coding, what is more important is that it
390   indicates what decoding mechanism will be required to remove the
391   encoding.
392</t>
393<t>
394   compress<iref item="compress (Coding Format)"/><iref item="Coding Format" subitem="compress"/>
395  <list>
396    <t>
397      See &compress-coding;.
398    </t>
399  </list>
400</t>
401<t>
402   deflate<iref item="deflate (Coding Format)"/><iref item="Coding Format" subitem="deflate"/>
403  <list>
404    <t>
405      See &deflate-coding;.
406    </t>
407  </list>
408</t>
409<t>
410   gzip<iref item="gzip (Coding Format)"/><iref item="Coding Format" subitem="gzip"/>
411  <list>
412    <t>
413      See &gzip-coding;.
414    </t>
415  </list>
416</t>
417<t>
418   identity<iref item="identity (Coding Format)"/><iref item="Coding Format" subitem="identity"/>
419  <list><t>
420        The default (identity) encoding; the use of no transformation
421        whatsoever. This content-coding is used only in the Accept-Encoding
422        header field, and &SHOULD-NOT;  be used in the Content-Encoding
423        header field.
424  </t></list>
425</t>
426
427<section title="Content Coding Registry" anchor="content.coding.registry">
428<t>
429   The HTTP Content Coding Registry defines the name space for the content
430   coding names.
431</t>
432<t>
433   Registrations &MUST; include the following fields:
434   <list style="symbols">
435     <t>Name</t>
436     <t>Description</t>
437     <t>Pointer to specification text</t>
438   </list>
439</t>
440<t>
441   Names of content codings &MUST-NOT; overlap with names of transfer codings
442   (&transfer-codings;), unless the encoding transformation is identical (as it
443   is the case for the compression codings defined in
444   &compression-codings;).
445</t>
446<t>
447   Values to be added to this name space require a specification
448   (see "Specification Required" in
449   <xref target="RFC5226" x:fmt="of" x:sec="4.1"/>), and &MUST;
450   conform to the purpose of content coding defined in this section.
451</t>
452<t>
453   The registry itself is maintained at
454   <eref target="http://www.iana.org/assignments/http-parameters"/>.
455</t>
456</section>
457
458</section>
459
460<section title="Media Types" anchor="media.types">
461  <x:anchor-alias value="media-type"/>
462  <x:anchor-alias value="type"/>
463  <x:anchor-alias value="subtype"/>
464<t>
465   HTTP uses Internet Media Types <xref target="RFC2046"/> in the Content-Type (<xref target="header.content-type"/>)
466   and Accept (<xref target="header.accept"/>) header fields in order to provide
467   open and extensible data typing and type negotiation.
468</t>
469<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="media-type"/><iref primary="true" item="Grammar" subitem="type"/><iref primary="true" item="Grammar" subitem="subtype"/>
470  <x:ref>media-type</x:ref> = <x:ref>type</x:ref> "/" <x:ref>subtype</x:ref> *( <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> <x:ref>parameter</x:ref> )
471  <x:ref>type</x:ref>       = <x:ref>token</x:ref>
472  <x:ref>subtype</x:ref>    = <x:ref>token</x:ref>
473</artwork></figure>
474<t anchor="rule.parameter">
475  <x:anchor-alias value="attribute"/>
476  <x:anchor-alias value="parameter"/>
477  <x:anchor-alias value="value"/>
478   The type/subtype &MAY; be followed by parameters in the form of
479   attribute/value pairs.
480</t>
481<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="parameter"/><iref primary="true" item="Grammar" subitem="attribute"/><iref primary="true" item="Grammar" subitem="value"/>
482  <x:ref>parameter</x:ref>      = <x:ref>attribute</x:ref> "=" <x:ref>value</x:ref>
483  <x:ref>attribute</x:ref>      = <x:ref>token</x:ref>
484  <x:ref>value</x:ref>          = <x:ref>word</x:ref>
485</artwork></figure>
486<t>
487   The type, subtype, and parameter attribute names are case-insensitive.
488   Parameter values might or might not be case-sensitive, depending on the
489   semantics of the parameter name.  The presence or absence of a parameter might
490   be significant to the processing of a media-type, depending on its
491   definition within the media type registry.
492</t>
493<t>
494   A parameter value that matches the <x:ref>token</x:ref> production can be
495   transmitted as either a token or within a quoted-string. The quoted and
496   unquoted values are equivalent.
497</t>
498<t>
499   Note that some older HTTP applications do not recognize media type
500   parameters. When sending data to older HTTP applications,
501   implementations &SHOULD; only use media type parameters when they are
502   required by that type/subtype definition.
503</t>
504<t>
505   Media-type values are registered with the Internet Assigned Number
506   Authority (IANA). The media type registration process is
507   outlined in <xref target="RFC4288"/>. Use of non-registered media types is
508   discouraged.
509</t>
510
511<section title="Canonicalization and Text Defaults" anchor="canonicalization.and.text.defaults">
512<t>
513   Internet media types are registered with a canonical form. A
514   representation transferred via HTTP messages &MUST; be in the
515   appropriate canonical form prior to its transmission except for
516   "text" types, as defined in the next paragraph.
517</t>
518<t>
519   When in canonical form, media subtypes of the "text" type use CRLF as
520   the text line break. HTTP relaxes this requirement and allows the
521   transport of text media with plain CR or LF alone representing a line
522   break when it is done consistently for an entire representation. HTTP
523   applications &MUST; accept CRLF, bare CR, and bare LF as indicating
524   a line break in text media received via HTTP. In
525   addition, if the text is in a character encoding that does not
526   use octets 13 and 10 for CR and LF respectively, as is the case for
527   some multi-byte character encodings, HTTP allows the use of whatever octet
528   sequences are defined by that character encoding to represent the
529   equivalent of CR and LF for line breaks. This flexibility regarding
530   line breaks applies only to text media in the payload body; a bare CR
531   or LF &MUST-NOT; be substituted for CRLF within any of the HTTP control
532   structures (such as header fields and multipart boundaries).
533</t>
534<t>
535   If a representation is encoded with a content-coding, the underlying
536   data &MUST; be in a form defined above prior to being encoded.
537</t>
538</section>
539
540<section title="Multipart Types" anchor="multipart.types">
541<t>
542   MIME provides for a number of "multipart" types &mdash; encapsulations of
543   one or more representations within a single message-body. All multipart
544   types share a common syntax, as defined in <xref target="RFC2046" x:sec="5.1.1" x:fmt="of"/>,
545   and &MUST; include a boundary parameter as part of the media type
546   value. The message body is itself a protocol element and &MUST;
547   therefore use only CRLF to represent line breaks between body-parts.
548</t>
549<t>
550   In general, HTTP treats a multipart message-body no differently than
551   any other media type: strictly as payload.  HTTP does not use the
552   multipart boundary as an indicator of message-body length.
553   <!-- jre: re-insert removed text pointing to caching? -->
554   In all other respects, an HTTP user agent &SHOULD; follow the same or similar
555   behavior as a MIME user agent would upon receipt of a multipart type.
556   The MIME header fields within each body-part of a multipart message-body
557   do not have any significance to HTTP beyond that defined by
558   their MIME semantics.
559</t>
560<t>
561   If an application receives an unrecognized multipart subtype, the
562   application &MUST; treat it as being equivalent to "multipart/mixed".
563</t>
564<x:note>
565  <t>
566    <x:h>Note:</x:h> The "multipart/form-data" type has been specifically defined
567    for carrying form data suitable for processing via the POST
568    request method, as described in <xref target="RFC2388"/>.
569  </t>
570</x:note>
571</section>
572</section>
573
574<section title="Language Tags" anchor="language.tags">
575  <x:anchor-alias value="language-tag"/>
576<t>
577   A language tag, as defined in <xref target="RFC5646"/>, identifies a
578   natural language spoken, written, or otherwise conveyed by human beings for
579   communication of information to other human beings. Computer languages are
580   explicitly excluded. HTTP uses language tags within the Accept-Language and
581   Content-Language fields.
582</t>
583<t>
584   In summary, a language tag is composed of one or more parts: A primary
585   language subtag followed by a possibly empty series of subtags:
586</t>
587<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="language-tag"/>
588  <x:ref>language-tag</x:ref> = &lt;Language-Tag, defined in <xref target="RFC5646" x:sec="2.1"/>&gt;
589</artwork></figure>
590<t>
591   White space is not allowed within the tag and all tags are case-insensitive.
592   The name space of language subtags is administered by the IANA (see
593   <eref target="http://www.iana.org/assignments/language-subtag-registry"/>).
594</t>
595<figure>
596  <preamble>Example tags include:</preamble>
597<artwork type="example">
598  en, en-US, es-419, az-Arab, x-pig-latin, man-Nkoo-GN
599</artwork>
600</figure>
601<t>
602   See <xref target="RFC5646"/> for further information.
603</t>
604</section>
605</section>
606
607<section title="Payload" anchor="payload">
608<t>
609   HTTP messages &MAY; transfer a payload if not otherwise restricted by
610   the request method or response status code.  The payload consists of
611   metadata, in the form of header fields, and data, in the form of the
612   sequence of octets in the message-body after any transfer-coding has
613   been decoded.
614</t>
615<iref item="payload"/>
616<t>   
617   A "<x:dfn>payload</x:dfn>" in HTTP is always a partial or complete
618   representation of some resource.  We use separate terms for payload
619   and representation because some messages contain only the associated
620   representation's header fields (e.g., responses to HEAD) or only some
621   part(s) of the representation (e.g., the 206 status code).
622</t>
623<section title="Payload Header Fields" anchor="payload.header.fields">
624  <x:anchor-alias value="payload-header"/>
625<t>
626   HTTP header fields that specifically define the payload, rather than the
627   associated representation, are referred to as "payload header fields".
628   The following payload header fields are defined by HTTP/1.1:
629</t>
630<texttable align="left">
631  <ttcol>Header Field Name</ttcol>
632  <ttcol>Defined in...</ttcol>
633
634  <c>Content-Length</c> <c>&header-content-length;</c>
635  <c>Content-Range</c> <c>&header-content-range;</c>
636</texttable>
637</section>
638
639<section title="Payload Body" anchor="payload.body">
640  <x:anchor-alias value="payload-body"/>
641<t>
642   A payload body is only present in a message when a message-body is
643   present, as described in &message-body;. The payload body is obtained
644   from the message-body by decoding any Transfer-Encoding that might
645   have been applied to ensure safe and proper transfer of the message.
646</t>
647</section>
648</section>
649
650<section title="Representation" anchor="representation">
651<iref item="representation"/>
652<t>
653   A "<x:dfn>representation</x:dfn>" is information in a format that can be readily
654   communicated from one party to another.  A resource representation
655   is information that reflects the state of that resource, as observed
656   at some point in the past (e.g., in a response to GET) or to be
657   desired at some point in the future (e.g., in a PUT request).
658</t>
659<t>
660   Most, but not all, representations transferred via HTTP are intended
661   to be a representation of the target resource (the resource identified
662   by the effective request URI).  The precise semantics of a representation
663   are determined by the type of message (request or response), the request
664   method, the response status code, and the representation metadata.
665   For example, the above semantic is true for the representation in any
666   200 (OK) response to GET and for the representation in any PUT request.
667   A 200 response to PUT, in contrast, contains either a representation
668   that describes the successful action or a representation of the target
669   resource, with the latter indicated by a Content-Location header field
670   with the same value as the effective request URI.  Likewise, response
671   messages with an error status code usually contain a representation that
672   describes the error and what next steps are suggested for resolving it.
673</t>
674
675<section title="Representation Header Fields" anchor="representation.header.fields">
676  <x:anchor-alias value="representation-header"/>
677<t>
678   Representation header fields define metadata about the representation data
679   enclosed in the message-body or, if no message-body is present, about
680   the representation that would have been transferred in a 200 response
681   to a simultaneous GET request with the same effective request URI.
682</t>
683<t>
684   The following header fields are defined as representation metadata:
685</t>
686<texttable align="left">
687  <ttcol>Header Field Name</ttcol>
688  <ttcol>Defined in...</ttcol>
689
690  <c>Content-Encoding</c> <c><xref target="header.content-encoding"/></c>
691  <c>Content-Language</c> <c><xref target="header.content-language"/></c>
692  <c>Content-Location</c> <c><xref target="header.content-location"/></c>
693  <c>Content-Type</c> <c><xref target="header.content-type"/></c>
694  <c>Expires</c> <c>&header-expires;</c>
695  <c>Last-Modified</c> <c>&header-last-modified;</c>
696</texttable>
697</section>
698
699<section title="Representation Data" anchor="representation.data">
700  <x:anchor-alias value="representation-data"/>
701<t>
702   The representation body associated with an HTTP message is
703   either provided as the payload body of the message or
704   referred to by the message semantics and the effective request
705   URI.  The representation data is in a format and encoding defined by
706   the representation metadata header fields.
707</t>
708<t>
709   The data type of the representation data
710   is determined via the header fields Content-Type and Content-Encoding.
711   These define a two-layer, ordered encoding model:
712</t>
713<figure><artwork type="example">
714  representation-data := Content-Encoding( Content-Type( bits ) )
715</artwork></figure>
716<t>
717   Content-Type specifies the media type of the underlying data, which
718   defines both the data format and how that data &SHOULD; be processed
719   by the recipient (within the scope of the request method semantics).
720   Any HTTP/1.1 message containing a payload body &SHOULD; include a
721   Content-Type header field defining the media type of the associated
722   representation unless that metadata is unknown to the sender.
723   If the Content-Type header field is not present, it indicates that
724   the sender does not know the media type of the representation;
725   recipients &MAY; either assume that the media type is
726   "application/octet-stream" (<xref target="RFC2046" x:fmt="," x:sec="4.5.1"/>)
727   or examine the content to determine its type.
728</t>
729<t>
730   In practice, resource owners do not always properly configure their origin
731   server to provide the correct Content-Type for a given representation,
732   with the result that some clients will examine a response body's content
733   and override the specified type.
734   Clients that do so risk drawing incorrect conclusions, which might expose
735   additional security risks (e.g., "privilege escalation").  Furthermore,
736   it is impossible to determine the sender's intent by examining the data
737   format: many data formats match multiple media types that differ only in
738   processing semantics.  Implementers are encouraged to provide a means of
739   disabling such "content sniffing" when it is used.
740</t>
741<t>
742   Content-Encoding is used to indicate any additional content
743   codings applied to the data, usually for the purpose of data
744   compression, that are a property of the representation.  If
745   Content-Encoding is not present, then there is no additional
746   encoding beyond that defined by the Content-Type.
747</t>
748</section>
749</section>
750
751<section title="Content Negotiation" anchor="content.negotiation">
752<t>
753   HTTP responses include a representation which contains information for
754   interpretation, whether by a human user or for further processing.
755   Often, the server has different ways of representing the
756   same information; for example, in different formats, languages,
757   or using different character encodings.
758</t>
759<t>
760   HTTP clients and their users might have different or variable
761   capabilities, characteristics or preferences which would influence
762   which representation, among those available from the server,
763   would be best for the server to deliver. For this reason, HTTP
764   provides mechanisms for "content negotiation" &mdash; a process of
765   allowing selection of a representation of a given resource,
766   when more than one is available.
767</t>
768<t>
769   This specification defines two patterns of content negotiation;
770   "server-driven", where the server selects the representation based
771   upon the client's stated preferences, and "agent-driven" negotiation,
772   where the server provides a list of representations for the client to
773   choose from, based upon their metadata. In addition,  there are
774   other patterns: some applications use an "active content" pattern,
775   where the server returns active content which runs on the client
776   and, based on client available parameters, selects additional
777   resources to invoke. "Transparent Content Negotiation" (<xref target="RFC2295"/>)
778   has also been proposed.
779</t>
780<t>
781   These patterns are all widely used, and have trade-offs in applicability
782   and practicality. In particular, when the number of preferences or
783   capabilities to be expressed by a client are large (such as when many
784   different formats are supported by a user-agent), server-driven
785   negotiation becomes unwieldy, and might not be appropriate. Conversely,
786   when the number of representations to choose from is very large,
787   agent-driven negotiation might not be appropriate.
788</t>
789<t>
790   Note that in all cases, the supplier of representations has the
791   responsibility for determining which representations might be
792   considered to be the "same information".
793</t>
794
795<section title="Server-driven Negotiation" anchor="server-driven.negotiation">
796<t>
797   If the selection of the best representation for a response is made by
798   an algorithm located at the server, it is called server-driven
799   negotiation. Selection is based on the available representations of
800   the response (the dimensions over which it can vary; e.g., language,
801   content-coding, etc.) and the contents of particular header fields in
802   the request message or on other information pertaining to the request
803   (such as the network address of the client).
804</t>
805<t>
806   Server-driven negotiation is advantageous when the algorithm for
807   selecting from among the available representations is difficult to
808   describe to the user agent, or when the server desires to send its
809   "best guess" to the client along with the first response (hoping to
810   avoid the round-trip delay of a subsequent request if the "best
811   guess" is good enough for the user). In order to improve the server's
812   guess, the user agent &MAY; include request header fields (Accept,
813   Accept-Language, Accept-Encoding, etc.) which describe its
814   preferences for such a response.
815</t>
816<t>
817   Server-driven negotiation has disadvantages:
818  <list style="numbers">
819    <t>
820         It is impossible for the server to accurately determine what
821         might be "best" for any given user, since that would require
822         complete knowledge of both the capabilities of the user agent
823         and the intended use for the response (e.g., does the user want
824         to view it on screen or print it on paper?).
825    </t>
826    <t>
827         Having the user agent describe its capabilities in every
828         request can be both very inefficient (given that only a small
829         percentage of responses have multiple representations) and a
830         potential violation of the user's privacy.
831    </t>
832    <t>
833         It complicates the implementation of an origin server and the
834         algorithms for generating responses to a request.
835    </t>
836    <t>
837         It might limit a public cache's ability to use the same response
838         for multiple user's requests.
839    </t>
840  </list>
841</t>
842<t>
843   HTTP/1.1 includes the following header fields for enabling
844   server-driven negotiation through description of user agent
845   capabilities and user preferences: Accept (<xref target="header.accept"/>), Accept-Charset
846   (<xref target="header.accept-charset"/>), Accept-Encoding (<xref target="header.accept-encoding"/>), Accept-Language
847   (<xref target="header.accept-language"/>), and User-Agent (&header-user-agent;).
848   However, an origin server is not limited to these dimensions and &MAY; vary
849   the response based on any aspect of the request, including aspects
850   of the connection (e.g., IP address) or information within extension
851   header fields not defined by this specification.
852</t>
853<x:note>
854  <t>
855    <x:h>Note:</x:h> In practice, User-Agent based negotiation is fragile,
856    because new clients might not be recognized.
857  </t>
858</x:note>
859<t>
860   The Vary header field (&header-vary;) can be used to express the parameters the
861   server uses to select a representation that is subject to server-driven
862   negotiation.
863</t>
864</section>
865
866<section title="Agent-driven Negotiation" anchor="agent-driven.negotiation">
867<t>
868   With agent-driven negotiation, selection of the best representation
869   for a response is performed by the user agent after receiving an
870   initial response from the origin server. Selection is based on a list
871   of the available representations of the response included within the
872   header fields or body of the initial response, with each
873   representation identified by its own URI. Selection from among the
874   representations can be performed automatically (if the user agent is
875   capable of doing so) or manually by the user selecting from a
876   generated (possibly hypertext) menu.
877</t>
878<t>
879   Agent-driven negotiation is advantageous when the response would vary
880   over commonly-used dimensions (such as type, language, or encoding),
881   when the origin server is unable to determine a user agent's
882   capabilities from examining the request, and generally when public
883   caches are used to distribute server load and reduce network usage.
884</t>
885<t>
886   Agent-driven negotiation suffers from the disadvantage of needing a
887   second request to obtain the best alternate representation. This
888   second request is only efficient when caching is used. In addition,
889   this specification does not define any mechanism for supporting
890   automatic selection, though it also does not prevent any such
891   mechanism from being developed as an extension and used within
892   HTTP/1.1.
893</t>
894<t>
895   This specification defines the 300 (Multiple Choices) and 406 (Not Acceptable)
896   status codes for enabling agent-driven negotiation when the server is
897   unwilling or unable to provide a varying response using server-driven
898   negotiation.
899</t>
900</section>
901</section>
902
903<section title="Header Field Definitions" anchor="header.fields">
904<t>
905   This section defines the syntax and semantics of HTTP/1.1 header fields
906   related to the payload of messages.
907</t>
908
909<section title="Accept" anchor="header.accept">
910  <iref primary="true" item="Accept header field" x:for-anchor=""/>
911  <iref primary="true" item="Header Fields" subitem="Accept" x:for-anchor=""/>
912  <x:anchor-alias value="Accept"/>
913  <x:anchor-alias value="accept-ext"/>
914  <x:anchor-alias value="accept-params"/>
915  <x:anchor-alias value="media-range"/>
916<t>
917   The "Accept" header field can be used by user agents to specify
918   response media types that are acceptable. Accept header fields can be used to
919   indicate that the request is specifically limited to a small set of desired
920   types, as in the case of a request for an in-line image.
921</t>
922<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept"/><iref primary="true" item="Grammar" subitem="media-range"/><iref primary="true" item="Grammar" subitem="accept-params"/><iref primary="true" item="Grammar" subitem="accept-ext"/>
923  <x:ref>Accept</x:ref> = #( <x:ref>media-range</x:ref> [ <x:ref>accept-params</x:ref> ] )
924 
925  <x:ref>media-range</x:ref>    = ( "*/*"
926                   / ( <x:ref>type</x:ref> "/" "*" )
927                   / ( <x:ref>type</x:ref> "/" <x:ref>subtype</x:ref> )
928                   ) *( <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> <x:ref>parameter</x:ref> )
929  <x:ref>accept-params</x:ref>  = <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> *( <x:ref>accept-ext</x:ref> )
930  <x:ref>accept-ext</x:ref>     = <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> <x:ref>token</x:ref> [ "=" <x:ref>word</x:ref> ]
931</artwork></figure>
932<t>
933   The asterisk "*" character is used to group media types into ranges,
934   with "*/*" indicating all media types and "type/*" indicating all
935   subtypes of that type. The media-range &MAY; include media type
936   parameters that are applicable to that range.
937</t>
938<t>
939   Each media-range &MAY; be followed by one or more accept-params,
940   beginning with the "q" parameter for indicating a relative quality
941   factor. The first "q" parameter (if any) separates the media-range
942   parameter(s) from the accept-params. Quality factors allow the user
943   or user agent to indicate the relative degree of preference for that
944   media-range, using the qvalue scale from 0 to 1 (&qvalue;). The
945   default value is q=1.
946</t>
947<x:note>
948  <t>
949    <x:h>Note:</x:h> Use of the "q" parameter name to separate media type
950    parameters from Accept extension parameters is due to historical
951    practice. Although this prevents any media type parameter named
952    "q" from being used with a media range, such an event is believed
953    to be unlikely given the lack of any "q" parameters in the IANA
954    media type registry and the rare usage of any media type
955    parameters in Accept. Future media types are discouraged from
956    registering any parameter named "q".
957  </t>
958</x:note>
959<t>
960   The example
961</t>
962<figure><artwork type="example">
963  Accept: audio/*; q=0.2, audio/basic
964</artwork></figure>
965<t>
966   &SHOULD; be interpreted as "I prefer audio/basic, but send me any audio
967   type if it is the best available after an 80% mark-down in quality".
968</t>
969<t>
970   If no Accept header field is present, then it is assumed that the
971   client accepts all media types. If an Accept header field is present,
972   and if the server cannot send a response which is acceptable
973   according to the combined Accept field value, then the server &SHOULD;
974   send a 406 (Not Acceptable) response.
975</t>
976<t>
977   A more elaborate example is
978</t>
979<figure><artwork type="example">
980  Accept: text/plain; q=0.5, text/html,
981          text/x-dvi; q=0.8, text/x-c
982</artwork></figure>
983<t>
984   Verbally, this would be interpreted as "text/html and text/x-c are
985   the preferred media types, but if they do not exist, then send the
986   text/x-dvi representation, and if that does not exist, send the text/plain
987   representation".
988</t>
989<t>
990   Media ranges can be overridden by more specific media ranges or
991   specific media types. If more than one media range applies to a given
992   type, the most specific reference has precedence. For example,
993</t>
994<figure><artwork type="example">
995  Accept: text/*, text/plain, text/plain;format=flowed, */*
996</artwork></figure>
997<t>
998   have the following precedence:
999   <list style="numbers">
1000    <t>text/plain;format=flowed</t>
1001    <t>text/plain</t>
1002    <t>text/*</t>
1003    <t>*/*</t>
1004   </list>
1005</t>
1006<t>
1007   The media type quality factor associated with a given type is
1008   determined by finding the media range with the highest precedence
1009   which matches that type. For example,
1010</t>
1011<figure><artwork type="example">
1012  Accept: text/*;q=0.3, text/html;q=0.7, text/html;level=1,
1013          text/html;level=2;q=0.4, */*;q=0.5
1014</artwork></figure>
1015<t>
1016   would cause the following values to be associated:
1017</t>
1018<texttable align="left">
1019  <ttcol>Media Type</ttcol><ttcol>Quality Value</ttcol>
1020  <c>text/html;level=1</c>    <c>1</c>
1021  <c>text/html</c>            <c>0.7</c>
1022  <c>text/plain</c>           <c>0.3</c>
1023  <c>image/jpeg</c>           <c>0.5</c>
1024  <c>text/html;level=2</c>    <c>0.4</c>
1025  <c>text/html;level=3</c>    <c>0.7</c>
1026</texttable>
1027<t>
1028      <x:h>Note:</x:h> A user agent might be provided with a default set of quality
1029      values for certain media ranges. However, unless the user agent is
1030      a closed system which cannot interact with other rendering agents,
1031      this default set ought to be configurable by the user.
1032</t>
1033</section>
1034
1035<section title="Accept-Charset" anchor="header.accept-charset">
1036  <iref primary="true" item="Accept-Charset header field" x:for-anchor=""/>
1037  <iref primary="true" item="Header Fields" subitem="Accept-Charset" x:for-anchor=""/>
1038  <x:anchor-alias value="Accept-Charset"/>
1039<t>
1040   The "Accept-Charset" header field can be used by user agents to
1041   indicate what character encodings are acceptable in a response
1042   payload. This field allows
1043   clients capable of understanding more comprehensive or special-purpose
1044   character encodings to signal that capability to a server which is capable of
1045   representing documents in those character encodings.
1046</t>
1047<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Charset"/>
1048  <x:ref>Accept-Charset</x:ref> = 1#( ( <x:ref>charset</x:ref> / "*" )
1049                         [ <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> ] )
1050</artwork></figure>
1051<t>
1052   Character encoding values (a.k.a., charsets) are described in
1053   <xref target="character.sets"/>. Each charset &MAY; be given an
1054   associated quality value which represents the user's preference
1055   for that charset. The default value is q=1. An example is
1056</t>
1057<figure><artwork type="example">
1058  Accept-Charset: iso-8859-5, unicode-1-1;q=0.8
1059</artwork></figure>
1060<t>
1061   The special value "*", if present in the Accept-Charset field,
1062   matches every character encoding which is not mentioned elsewhere in the
1063   Accept-Charset field. If no "*" is present in an Accept-Charset field, then
1064   all character encodings not explicitly mentioned get a quality value of 0.
1065</t>
1066<t>
1067   If no Accept-Charset header field is present, the default is that any
1068   character encoding is acceptable. If an Accept-Charset header field is present,
1069   and if the server cannot send a response which is acceptable
1070   according to the Accept-Charset header field, then the server &SHOULD; send
1071   an error response with the 406 (Not Acceptable) status code, though
1072   the sending of an unacceptable response is also allowed.
1073</t>
1074</section>
1075
1076<section title="Accept-Encoding" anchor="header.accept-encoding">
1077  <iref primary="true" item="Accept-Encoding header field" x:for-anchor=""/>
1078  <iref primary="true" item="Header Fields" subitem="Accept-Encoding" x:for-anchor=""/>
1079  <x:anchor-alias value="Accept-Encoding"/>
1080  <x:anchor-alias value="codings"/>
1081<t>
1082   The "Accept-Encoding" header field can be used by user agents to
1083   indicate what response content-codings (<xref target="content.codings"/>)
1084   are acceptable in the response.
1085</t>
1086<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Encoding"/><iref primary="true" item="Grammar" subitem="codings"/>
1087  <x:ref>Accept-Encoding</x:ref>  = #( <x:ref>codings</x:ref> [ <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> ] )
1088  <x:ref>codings</x:ref>          = ( <x:ref>content-coding</x:ref> / "*" )
1089</artwork></figure>
1090<t>
1091   Each codings value &MAY; be given an associated quality value which
1092   represents the preference for that encoding. The default value is q=1.
1093</t>
1094<t>
1095   Examples of its use are:
1096</t>
1097<figure><artwork type="example">
1098  Accept-Encoding: compress, gzip
1099  Accept-Encoding:
1100  Accept-Encoding: *
1101  Accept-Encoding: compress;q=0.5, gzip;q=1.0
1102  Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0
1103</artwork></figure>
1104<t>
1105   A server tests whether a content-coding is acceptable, according to
1106   an Accept-Encoding field, using these rules:
1107  <list style="numbers">
1108      <t>If the content-coding is one of the content-codings listed in
1109         the Accept-Encoding field, then it is acceptable, unless it is
1110         accompanied by a qvalue of 0. (As defined in &qvalue;, a
1111         qvalue of 0 means "not acceptable".)</t>
1112
1113      <t>The special "*" symbol in an Accept-Encoding field matches any
1114         available content-coding not explicitly listed in the header
1115         field.</t>
1116
1117      <t>If multiple content-codings are acceptable, then the acceptable
1118         content-coding with the highest non-zero qvalue is preferred.</t>
1119
1120      <t>The "identity" content-coding is always acceptable, unless
1121         specifically refused because the Accept-Encoding field includes
1122         "identity;q=0", or because the field includes "*;q=0" and does
1123         not explicitly include the "identity" content-coding. If the
1124         Accept-Encoding field-value is empty, then only the "identity"
1125         encoding is acceptable.</t>
1126  </list>
1127</t>
1128<t>
1129   If an Accept-Encoding field is present in a request, and if the
1130   server cannot send a response which is acceptable according to the
1131   Accept-Encoding header field, then the server &SHOULD; send an error response
1132   with the 406 (Not Acceptable) status code.
1133</t>
1134<t>
1135   If no Accept-Encoding field is present in a request, the server &MAY;
1136   assume that the client will accept any content coding. In this case,
1137   if "identity" is one of the available content-codings, then the
1138   server &SHOULD; use the "identity" content-coding, unless it has
1139   additional information that a different content-coding is meaningful
1140   to the client.
1141</t>
1142<x:note>
1143  <t>
1144    <x:h>Note:</x:h> If the request does not include an Accept-Encoding field,
1145    and if the "identity" content-coding is unavailable, then
1146    content-codings commonly understood by HTTP/1.0 clients (i.e.,
1147    "gzip" and "compress") are preferred; some older clients
1148    improperly display messages sent with other content-codings.  The
1149    server might also make this decision based on information about
1150    the particular user-agent or client.
1151  </t>
1152</x:note>
1153<x:note>
1154  <t>
1155    <x:h>Note:</x:h> Most HTTP/1.0 applications do not recognize or obey qvalues
1156    associated with content-codings. This means that qvalues will not
1157    work and are not permitted with x-gzip or x-compress.
1158  </t>
1159</x:note>
1160</section>
1161
1162<section title="Accept-Language" anchor="header.accept-language">
1163  <iref primary="true" item="Accept-Language header field" x:for-anchor=""/>
1164  <iref primary="true" item="Header Fields" subitem="Accept-Language" x:for-anchor=""/>
1165  <x:anchor-alias value="Accept-Language"/>
1166  <x:anchor-alias value="language-range"/>
1167<t>
1168   The "Accept-Language" header field can be used by user agents to
1169   indicate the set of natural languages that are preferred in the response.
1170   Language tags are defined in <xref target="language.tags"/>.
1171</t>
1172<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Language"/><iref primary="true" item="Grammar" subitem="language-range"/>
1173  <x:ref>Accept-Language</x:ref> =
1174                    1#( <x:ref>language-range</x:ref> [ <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> ] )
1175  <x:ref>language-range</x:ref>  =
1176            &lt;language-range, defined in <xref target="RFC4647" x:fmt="," x:sec="2.1"/>&gt;
1177</artwork></figure>
1178<t>
1179   Each language-range can be given an associated quality value which
1180   represents an estimate of the user's preference for the languages
1181   specified by that range. The quality value defaults to "q=1". For
1182   example,
1183</t>
1184<figure><artwork type="example">
1185  Accept-Language: da, en-gb;q=0.8, en;q=0.7
1186</artwork></figure>
1187<t>
1188   would mean: "I prefer Danish, but will accept British English and
1189   other types of English".
1190   (see also <xref target="RFC4647" x:sec="2.3" x:fmt="of"/>)
1191</t>
1192<t>
1193   For matching, <xref target="RFC4647" x:sec="3" x:fmt="of"/> defines
1194   several matching schemes. Implementations can offer the most appropriate
1195   matching scheme for their requirements.
1196</t>
1197<x:note>
1198  <t>
1199    <x:h>Note:</x:h> The "Basic Filtering" scheme (<xref target="RFC4647"
1200    x:fmt="," x:sec="3.3.1"/>) is identical to the matching scheme that was
1201    previously defined in <xref target="RFC2616" x:fmt="of" x:sec="14.4"/>.
1202  </t>
1203</x:note>
1204<t>
1205   It might be contrary to the privacy expectations of the user to send
1206   an Accept-Language header field with the complete linguistic preferences of
1207   the user in every request. For a discussion of this issue, see
1208   <xref target="privacy.issues.connected.to.accept.header.fields"/>.
1209</t>
1210<t>
1211   As intelligibility is highly dependent on the individual user, it is
1212   recommended that client applications make the choice of linguistic
1213   preference available to the user. If the choice is not made
1214   available, then the Accept-Language header field &MUST-NOT; be given in
1215   the request.
1216</t>
1217<x:note>
1218  <t>
1219    <x:h>Note:</x:h> When making the choice of linguistic preference available to
1220    the user, we remind implementors of  the fact that users are not
1221    familiar with the details of language matching as described above,
1222    and ought to be provided appropriate guidance. As an example, users
1223    might assume that on selecting "en-gb", they will be served any
1224    kind of English document if British English is not available. A
1225    user agent might suggest in such a case to add "en" to get the
1226    best matching behavior.
1227  </t>
1228</x:note>
1229</section>
1230
1231<section title="Content-Encoding" anchor="header.content-encoding">
1232  <iref primary="true" item="Content-Encoding header field" x:for-anchor=""/>
1233  <iref primary="true" item="Header Fields" subitem="Content-Encoding" x:for-anchor=""/>
1234  <x:anchor-alias value="Content-Encoding"/>
1235<t>
1236   The "Content-Encoding" header field indicates what content-codings
1237   have been applied to the representation, and thus what decoding mechanisms
1238   must be applied in order to obtain the media-type referenced by the
1239   Content-Type header field. Content-Encoding is primarily used to allow a
1240   representation to be compressed without losing the identity of its underlying
1241   media type.
1242</t>
1243<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Encoding"/>
1244  <x:ref>Content-Encoding</x:ref> = 1#<x:ref>content-coding</x:ref>
1245</artwork></figure>
1246<t>
1247   Content codings are defined in <xref target="content.codings"/>. An example of its use is
1248</t>
1249<figure><artwork type="example">
1250  Content-Encoding: gzip
1251</artwork></figure>
1252<t>
1253   The content-coding is a characteristic of the representation.
1254   Typically, the representation body is stored with this
1255   encoding and is only decoded before rendering or analogous usage.
1256   However, a transforming proxy &MAY; modify the content-coding if the
1257   new coding is known to be acceptable to the recipient, unless the
1258   "no-transform" cache-control directive is present in the message.
1259</t>
1260<t>
1261   If the content-coding of a representation is not "identity", then the
1262   representation metadata &MUST; include a Content-Encoding header
1263   field (<xref target="header.content-encoding"/>)
1264   that lists the non-identity content-coding(s) used.
1265</t>
1266<t>
1267   If the content-coding of a representation in a request message is not
1268   acceptable to the origin server, the server &SHOULD; respond with a
1269   status code of 415 (Unsupported Media Type).
1270</t>
1271<t>
1272   If multiple encodings have been applied to a representation, the content
1273   codings &MUST; be listed in the order in which they were applied.
1274   Additional information about the encoding parameters &MAY; be provided
1275   by other header fields not defined by this specification.
1276</t>
1277</section>
1278
1279<section title="Content-Language" anchor="header.content-language">
1280  <iref primary="true" item="Content-Language header field" x:for-anchor=""/>
1281  <iref primary="true" item="Header Fields" subitem="Content-Language" x:for-anchor=""/>
1282  <x:anchor-alias value="Content-Language"/>
1283<t>
1284   The "Content-Language" header field describes the natural
1285   language(s) of the intended audience for the representation. Note that this might
1286   not be equivalent to all the languages used within the representation.
1287</t>
1288<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Language"/>
1289  <x:ref>Content-Language</x:ref> = 1#<x:ref>language-tag</x:ref>
1290</artwork></figure>
1291<t>
1292   Language tags are defined in <xref target="language.tags"/>. The primary purpose of
1293   Content-Language is to allow a user to identify and differentiate
1294   representations according to the user's own preferred language. Thus, if the
1295   body content is intended only for a Danish-literate audience, the
1296   appropriate field is
1297</t>
1298<figure><artwork type="example">
1299  Content-Language: da
1300</artwork></figure>
1301<t>
1302   If no Content-Language is specified, the default is that the content
1303   is intended for all language audiences. This might mean that the
1304   sender does not consider it to be specific to any natural language,
1305   or that the sender does not know for which language it is intended.
1306</t>
1307<t>
1308   Multiple languages &MAY; be listed for content that is intended for
1309   multiple audiences. For example, a rendition of the "Treaty of
1310   Waitangi", presented simultaneously in the original Maori and English
1311   versions, would call for
1312</t>
1313<figure><artwork type="example">
1314  Content-Language: mi, en
1315</artwork></figure>
1316<t>
1317   However, just because multiple languages are present within a representation
1318   does not mean that it is intended for multiple linguistic audiences.
1319   An example would be a beginner's language primer, such as "A First
1320   Lesson in Latin", which is clearly intended to be used by an
1321   English-literate audience. In this case, the Content-Language would
1322   properly only include "en".
1323</t>
1324<t>
1325   Content-Language &MAY; be applied to any media type &mdash; it is not
1326   limited to textual documents.
1327</t>
1328</section>
1329
1330<section title="Content-Location" anchor="header.content-location">
1331  <iref primary="true" item="Content-Location header field" x:for-anchor=""/>
1332  <iref primary="true" item="Header Fields" subitem="Content-Location" x:for-anchor=""/>
1333  <x:anchor-alias value="Content-Location"/>
1334<t>
1335   The "Content-Location" header field supplies a URI that can be used
1336   as a specific identifier for the representation in this message.
1337   In other words, if one were to perform a GET on this URI at the time
1338   of this message's generation, then a 200 response would contain the
1339   same representation that is enclosed as payload in this message.
1340</t>
1341<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Location"/>
1342  <x:ref>Content-Location</x:ref> = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
1343</artwork></figure>
1344<t>
1345   The Content-Location value is not a replacement for the effective
1346   Request URI (&effective-request-uri;).  It is representation metadata.
1347   It has the same syntax and semantics as the header field of the same name
1348   defined for MIME body parts in <xref target="RFC2557" x:fmt="of" x:sec="4"/>.
1349   However, its appearance in an HTTP message has some special implications
1350   for HTTP recipients.
1351</t>
1352<t>
1353   If Content-Location is included in a response message and its value
1354   is the same as the effective request URI, then the response payload
1355   &SHOULD; be considered the current representation of that resource.
1356   For a GET or HEAD request, this is the same as the default semantics
1357   when no Content-Location is provided by the server.  For a state-changing
1358   request like PUT or POST, it implies that the server's response contains
1359   the new representation of that resource, thereby distinguishing it from
1360   representations that might only report about the action (e.g., "It worked!").
1361   This allows authoring applications to update their local copies without
1362   the need for a subsequent GET request.
1363</t>
1364<t>
1365   If Content-Location is included in a response message and its value
1366   differs from the effective request URI, then the origin server is
1367   informing recipients that this representation has its own, presumably
1368   more specific, identifier.  For a GET or HEAD request, this is an
1369   indication that the effective request URI identifies a resource that
1370   is subject to content negotiation and the representation selected for
1371   this response can also be found at the identified URI.  For other
1372   methods, such a Content-Location indicates that this representation
1373   contains a report on the action's status and the same report is
1374   available (for future access with GET) at the given URI.  For
1375   example, a purchase transaction made via a POST request might
1376   include a receipt document as the payload of the 200 response;
1377   the Content-Location value provides an identifier for retrieving
1378   a copy of that same receipt in the future.
1379</t>
1380<t>
1381   If Content-Location is included in a request message, then it &MAY;
1382   be interpreted by the origin server as an indication of where the
1383   user agent originally obtained the content of the enclosed
1384   representation (prior to any subsequent modification of the content
1385   by that user agent).  In other words, the user agent is providing
1386   the same representation metadata that it received with the original
1387   representation.  However, such interpretation &MUST-NOT; be used to
1388   alter the semantics of the method requested by the client.  For
1389   example, if a client makes a PUT request on a negotiated resource
1390   and the origin server accepts that PUT (without redirection), then the
1391   new set of values for that resource is expected to be consistent with
1392   the one representation supplied in that PUT; the Content-Location
1393   cannot be used as a form of reverse content selection that
1394   identifies only one of the negotiated representations to be updated.
1395   If the user agent had wanted the latter semantics, it would have applied
1396   the PUT directly to the Content-Location URI.
1397</t>
1398<t>
1399   A Content-Location field received in a request message is transitory
1400   information that &SHOULD-NOT; be saved with other representation
1401   metadata for use in later responses.  The Content-Location's value
1402   might be saved for use in other contexts, such as within source links
1403   or other metadata.
1404</t>
1405<t>
1406   A cache cannot assume that a representation with a Content-Location
1407   different from the URI used to retrieve it can be used to respond to
1408   later requests on that Content-Location URI.
1409</t>
1410<t>
1411   If the Content-Location value is a partial URI, the partial URI is
1412   interpreted relative to the effective request URI.
1413</t>
1414</section>
1415
1416<section title="Content-Type" anchor="header.content-type">
1417  <iref primary="true" item="Content-Type header field" x:for-anchor=""/>
1418  <iref primary="true" item="Header Fields" subitem="Content-Type" x:for-anchor=""/>
1419  <x:anchor-alias value="Content-Type"/>
1420<t>
1421   The "Content-Type" header field indicates the media type of the
1422   representation. In the case of responses to the HEAD method, the media type is
1423   that which would have been sent had the request been a GET.
1424</t>
1425<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Type"/>
1426  <x:ref>Content-Type</x:ref> = <x:ref>media-type</x:ref>
1427</artwork></figure>
1428<t>
1429   Media types are defined in <xref target="media.types"/>. An example of the field is
1430</t>
1431<figure><artwork type="example">
1432  Content-Type: text/html; charset=ISO-8859-4
1433</artwork></figure>
1434<t>
1435   Further discussion of Content-Type is provided in <xref target="representation.data"/>.
1436</t>
1437</section>
1438
1439</section>
1440
1441<section title="IANA Considerations" anchor="IANA.considerations">
1442<section title="Header Field Registration" anchor="header.field.registration">
1443<t>
1444   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
1445   with the permanent registrations below (see <xref target="RFC3864"/>):
1446</t>
1447<?BEGININC p3-payload.iana-headers ?>
1448<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
1449<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
1450   <ttcol>Header Field Name</ttcol>
1451   <ttcol>Protocol</ttcol>
1452   <ttcol>Status</ttcol>
1453   <ttcol>Reference</ttcol>
1454
1455   <c>Accept</c>
1456   <c>http</c>
1457   <c>standard</c>
1458   <c>
1459      <xref target="header.accept"/>
1460   </c>
1461   <c>Accept-Charset</c>
1462   <c>http</c>
1463   <c>standard</c>
1464   <c>
1465      <xref target="header.accept-charset"/>
1466   </c>
1467   <c>Accept-Encoding</c>
1468   <c>http</c>
1469   <c>standard</c>
1470   <c>
1471      <xref target="header.accept-encoding"/>
1472   </c>
1473   <c>Accept-Language</c>
1474   <c>http</c>
1475   <c>standard</c>
1476   <c>
1477      <xref target="header.accept-language"/>
1478   </c>
1479   <c>Content-Encoding</c>
1480   <c>http</c>
1481   <c>standard</c>
1482   <c>
1483      <xref target="header.content-encoding"/>
1484   </c>
1485   <c>Content-Language</c>
1486   <c>http</c>
1487   <c>standard</c>
1488   <c>
1489      <xref target="header.content-language"/>
1490   </c>
1491   <c>Content-Location</c>
1492   <c>http</c>
1493   <c>standard</c>
1494   <c>
1495      <xref target="header.content-location"/>
1496   </c>
1497   <c>Content-Type</c>
1498   <c>http</c>
1499   <c>standard</c>
1500   <c>
1501      <xref target="header.content-type"/>
1502   </c>
1503   <c>MIME-Version</c>
1504   <c>http</c>
1505   <c>standard</c>
1506   <c>
1507      <xref target="mime-version"/>
1508   </c>
1509</texttable>
1510<!--(END)-->
1511<?ENDINC p3-payload.iana-headers ?>
1512<t>
1513   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
1514</t>
1515</section>
1516
1517<section title="Content Coding Registry" anchor="content.coding.registration">
1518<t>
1519   The registration procedure for HTTP Content Codings is now defined
1520   by <xref target="content.coding.registry"/> of this document.
1521</t>
1522<t>
1523   The HTTP Content Codings Registry located at <eref target="http://www.iana.org/assignments/http-parameters"/>
1524   shall be updated with the registration below:
1525</t>
1526<texttable align="left" suppress-title="true" anchor="iana.content.coding.registration.table">
1527   <ttcol>Name</ttcol>
1528   <ttcol>Description</ttcol>
1529   <ttcol>Reference</ttcol>
1530   <c>compress</c>
1531   <c>UNIX "compress" program method</c>
1532   <c>
1533      &compress-coding;
1534   </c>
1535   <c>deflate</c>
1536   <c>"deflate" compression mechanism (<xref target="RFC1951"/>) used inside
1537   the "zlib" data format (<xref target="RFC1950"/>)
1538   </c>
1539   <c>
1540      &deflate-coding;
1541   </c>
1542   <c>gzip</c>
1543   <c>Same as GNU zip <xref target="RFC1952"/></c>
1544   <c>
1545      &gzip-coding;
1546   </c>
1547   <c>identity</c>
1548   <c>No transformation</c>
1549   <c>
1550      <xref target="content.codings"/>
1551   </c>
1552</texttable>
1553</section>
1554
1555</section>
1556
1557<section title="Security Considerations" anchor="security.considerations">
1558<t>
1559   This section is meant to inform application developers, information
1560   providers, and users of the security limitations in HTTP/1.1 as
1561   described by this document. The discussion does not include
1562   definitive solutions to the problems revealed, though it does make
1563   some suggestions for reducing security risks.
1564</t>
1565
1566<section title="Privacy Issues Connected to Accept Header Fields" anchor="privacy.issues.connected.to.accept.header.fields">
1567<t>
1568   Accept headers fields can reveal information about the user to all
1569   servers which are accessed. The Accept-Language header field in particular
1570   can reveal information the user would consider to be of a private
1571   nature, because the understanding of particular languages is often
1572   strongly correlated to the membership of a particular ethnic group.
1573   User agents which offer the option to configure the contents of an
1574   Accept-Language header field to be sent in every request are strongly
1575   encouraged to let the configuration process include a message which
1576   makes the user aware of the loss of privacy involved.
1577</t>
1578<t>
1579   An approach that limits the loss of privacy would be for a user agent
1580   to omit the sending of Accept-Language header fields by default, and to ask
1581   the user whether or not to start sending Accept-Language header fields to a
1582   server if it detects, by looking for any Vary header fields
1583   generated by the server, that such sending could improve the quality
1584   of service.
1585</t>
1586<t>
1587   Elaborate user-customized accept header fields sent in every request,
1588   in particular if these include quality values, can be used by servers
1589   as relatively reliable and long-lived user identifiers. Such user
1590   identifiers would allow content providers to do click-trail tracking,
1591   and would allow collaborating content providers to match cross-server
1592   click-trails or form submissions of individual users. Note that for
1593   many users not behind a proxy, the network address of the host
1594   running the user agent will also serve as a long-lived user
1595   identifier. In environments where proxies are used to enhance
1596   privacy, user agents ought to be conservative in offering accept
1597   header configuration options to end users. As an extreme privacy
1598   measure, proxies could filter the accept header fields in relayed requests.
1599   General purpose user agents which provide a high degree of header
1600   configurability &SHOULD; warn users about the loss of privacy which can
1601   be involved.
1602</t>
1603</section>
1604
1605</section>
1606
1607<section title="Acknowledgments" anchor="ack">
1608</section>
1609</middle>
1610<back>
1611
1612<references title="Normative References">
1613
1614<reference anchor="Part1">
1615  <front>
1616    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
1617    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1618      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1619      <address><email>fielding@gbiv.com</email></address>
1620    </author>
1621    <author initials="J." surname="Gettys" fullname="Jim Gettys">
1622      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1623      <address><email>jg@freedesktop.org</email></address>
1624    </author>
1625    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1626      <organization abbrev="HP">Hewlett-Packard Company</organization>
1627      <address><email>JeffMogul@acm.org</email></address>
1628    </author>
1629    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1630      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1631      <address><email>henrikn@microsoft.com</email></address>
1632    </author>
1633    <author initials="L." surname="Masinter" fullname="Larry Masinter">
1634      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1635      <address><email>LMM@acm.org</email></address>
1636    </author>
1637    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1638      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1639      <address><email>paulle@microsoft.com</email></address>
1640    </author>
1641    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1642      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1643      <address><email>timbl@w3.org</email></address>
1644    </author>
1645    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1646      <organization abbrev="W3C">World Wide Web Consortium</organization>
1647      <address><email>ylafon@w3.org</email></address>
1648    </author>
1649    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1650      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1651      <address><email>julian.reschke@greenbytes.de</email></address>
1652    </author>
1653    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1654  </front>
1655  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
1656  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
1657</reference>
1658
1659<reference anchor="Part2">
1660  <front>
1661    <title abbrev="HTTP/1.1">HTTP/1.1, part 2: Message Semantics</title>
1662    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1663      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1664      <address><email>fielding@gbiv.com</email></address>
1665    </author>
1666    <author initials="J." surname="Gettys" fullname="Jim Gettys">
1667      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1668      <address><email>jg@freedesktop.org</email></address>
1669    </author>
1670    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1671      <organization abbrev="HP">Hewlett-Packard Company</organization>
1672      <address><email>JeffMogul@acm.org</email></address>
1673    </author>
1674    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1675      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1676      <address><email>henrikn@microsoft.com</email></address>
1677    </author>
1678    <author initials="L." surname="Masinter" fullname="Larry Masinter">
1679      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1680      <address><email>LMM@acm.org</email></address>
1681    </author>
1682    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1683      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1684      <address><email>paulle@microsoft.com</email></address>
1685    </author>
1686    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1687      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1688      <address><email>timbl@w3.org</email></address>
1689    </author>
1690    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1691      <organization abbrev="W3C">World Wide Web Consortium</organization>
1692      <address><email>ylafon@w3.org</email></address>
1693    </author>
1694    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1695      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1696      <address><email>julian.reschke@greenbytes.de</email></address>
1697    </author>
1698    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1699  </front>
1700  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"/>
1701  <x:source href="p2-semantics.xml" basename="p2-semantics"/>
1702</reference>
1703
1704<reference anchor="Part4">
1705  <front>
1706    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
1707    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1708      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1709      <address><email>fielding@gbiv.com</email></address>
1710    </author>
1711    <author initials="J." surname="Gettys" fullname="Jim Gettys">
1712      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1713      <address><email>jg@freedesktop.org</email></address>
1714    </author>
1715    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1716      <organization abbrev="HP">Hewlett-Packard Company</organization>
1717      <address><email>JeffMogul@acm.org</email></address>
1718    </author>
1719    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1720      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1721      <address><email>henrikn@microsoft.com</email></address>
1722    </author>
1723    <author initials="L." surname="Masinter" fullname="Larry Masinter">
1724      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1725      <address><email>LMM@acm.org</email></address>
1726    </author>
1727    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1728      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1729      <address><email>paulle@microsoft.com</email></address>
1730    </author>
1731    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1732      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1733      <address><email>timbl@w3.org</email></address>
1734    </author>
1735    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1736      <organization abbrev="W3C">World Wide Web Consortium</organization>
1737      <address><email>ylafon@w3.org</email></address>
1738    </author>
1739    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1740      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1741      <address><email>julian.reschke@greenbytes.de</email></address>
1742    </author>
1743    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1744  </front>
1745  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
1746  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
1747</reference>
1748
1749<reference anchor="Part5">
1750  <front>
1751    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
1752    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1753      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1754      <address><email>fielding@gbiv.com</email></address>
1755    </author>
1756    <author initials="J." surname="Gettys" fullname="Jim Gettys">
1757      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1758      <address><email>jg@freedesktop.org</email></address>
1759    </author>
1760    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1761      <organization abbrev="HP">Hewlett-Packard Company</organization>
1762      <address><email>JeffMogul@acm.org</email></address>
1763    </author>
1764    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1765      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1766      <address><email>henrikn@microsoft.com</email></address>
1767    </author>
1768    <author initials="L." surname="Masinter" fullname="Larry Masinter">
1769      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1770      <address><email>LMM@acm.org</email></address>
1771    </author>
1772    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1773      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1774      <address><email>paulle@microsoft.com</email></address>
1775    </author>
1776    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1777      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1778      <address><email>timbl@w3.org</email></address>
1779    </author>
1780    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1781      <organization abbrev="W3C">World Wide Web Consortium</organization>
1782      <address><email>ylafon@w3.org</email></address>
1783    </author>
1784    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1785      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1786      <address><email>julian.reschke@greenbytes.de</email></address>
1787    </author>
1788    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1789  </front>
1790  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
1791  <x:source href="p5-range.xml" basename="p5-range"/>
1792</reference>
1793
1794<reference anchor="Part6">
1795  <front>
1796    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
1797    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1798      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1799      <address><email>fielding@gbiv.com</email></address>
1800    </author>
1801    <author initials="J." surname="Gettys" fullname="Jim Gettys">
1802      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1803      <address><email>jg@freedesktop.org</email></address>
1804    </author>
1805    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1806      <organization abbrev="HP">Hewlett-Packard Company</organization>
1807      <address><email>JeffMogul@acm.org</email></address>
1808    </author>
1809    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1810      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1811      <address><email>henrikn@microsoft.com</email></address>
1812    </author>
1813    <author initials="L." surname="Masinter" fullname="Larry Masinter">
1814      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1815      <address><email>LMM@acm.org</email></address>
1816    </author>
1817    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1818      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1819      <address><email>paulle@microsoft.com</email></address>
1820    </author>
1821    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1822      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1823      <address><email>timbl@w3.org</email></address>
1824    </author>
1825    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1826      <organization abbrev="W3C">World Wide Web Consortium</organization>
1827      <address><email>ylafon@w3.org</email></address>
1828    </author>
1829    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
1830      <address><email>mnot@mnot.net</email></address>
1831    </author>
1832    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1833      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1834      <address><email>julian.reschke@greenbytes.de</email></address>
1835    </author>
1836    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1837  </front>
1838  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
1839  <x:source href="p6-cache.xml" basename="p6-cache"/>
1840</reference>
1841
1842<reference anchor="RFC1950">
1843  <front>
1844    <title>ZLIB Compressed Data Format Specification version 3.3</title>
1845    <author initials="L.P." surname="Deutsch" fullname="L. Peter Deutsch">
1846      <organization>Aladdin Enterprises</organization>
1847      <address><email>ghost@aladdin.com</email></address>
1848    </author>
1849    <author initials="J-L." surname="Gailly" fullname="Jean-Loup Gailly"/>
1850    <date month="May" year="1996"/>
1851  </front>
1852  <seriesInfo name="RFC" value="1950"/>
1853  <annotation>
1854    RFC 1950 is an Informational RFC, thus it might be less stable than
1855    this specification. On the other hand, this downward reference was
1856    present since the publication of RFC 2068 in 1997 (<xref target="RFC2068"/>),
1857    therefore it is unlikely to cause problems in practice. See also
1858    <xref target="BCP97"/>.
1859  </annotation>
1860</reference>
1861
1862<reference anchor="RFC1951">
1863  <front>
1864    <title>DEFLATE Compressed Data Format Specification version 1.3</title>
1865    <author initials="P." surname="Deutsch" fullname="L. Peter Deutsch">
1866      <organization>Aladdin Enterprises</organization>
1867      <address><email>ghost@aladdin.com</email></address>
1868    </author>
1869    <date month="May" year="1996"/>
1870  </front>
1871  <seriesInfo name="RFC" value="1951"/>
1872  <annotation>
1873    RFC 1951 is an Informational RFC, thus it might be less stable than
1874    this specification. On the other hand, this downward reference was
1875    present since the publication of RFC 2068 in 1997 (<xref target="RFC2068"/>),
1876    therefore it is unlikely to cause problems in practice. See also
1877    <xref target="BCP97"/>.
1878  </annotation>
1879</reference>
1880
1881<reference anchor="RFC1952">
1882  <front>
1883    <title>GZIP file format specification version 4.3</title>
1884    <author initials="P." surname="Deutsch" fullname="L. Peter Deutsch">
1885      <organization>Aladdin Enterprises</organization>
1886      <address><email>ghost@aladdin.com</email></address>
1887    </author>
1888    <author initials="J-L." surname="Gailly" fullname="Jean-Loup Gailly">
1889      <address><email>gzip@prep.ai.mit.edu</email></address>
1890    </author>
1891    <author initials="M." surname="Adler" fullname="Mark Adler">
1892      <address><email>madler@alumni.caltech.edu</email></address>
1893    </author>
1894    <author initials="L.P." surname="Deutsch" fullname="L. Peter Deutsch">
1895      <address><email>ghost@aladdin.com</email></address>
1896    </author>
1897    <author initials="G." surname="Randers-Pehrson" fullname="Glenn Randers-Pehrson">
1898      <address><email>randeg@alumni.rpi.edu</email></address>
1899    </author>
1900    <date month="May" year="1996"/>
1901  </front>
1902  <seriesInfo name="RFC" value="1952"/>
1903  <annotation>
1904    RFC 1952 is an Informational RFC, thus it might be less stable than
1905    this specification. On the other hand, this downward reference was
1906    present since the publication of RFC 2068 in 1997 (<xref target="RFC2068"/>),
1907    therefore it is unlikely to cause problems in practice. See also
1908    <xref target="BCP97"/>.
1909  </annotation>
1910</reference>
1911
1912<reference anchor="RFC2045">
1913  <front>
1914    <title abbrev="Internet Message Bodies">Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</title>
1915    <author initials="N." surname="Freed" fullname="Ned Freed">
1916      <organization>Innosoft International, Inc.</organization>
1917      <address><email>ned@innosoft.com</email></address>
1918    </author>
1919    <author initials="N.S." surname="Borenstein" fullname="Nathaniel S. Borenstein">
1920      <organization>First Virtual Holdings</organization>
1921      <address><email>nsb@nsb.fv.com</email></address>
1922    </author>
1923    <date month="November" year="1996"/>
1924  </front>
1925  <seriesInfo name="RFC" value="2045"/>
1926</reference>
1927
1928<reference anchor="RFC2046">
1929  <front>
1930    <title abbrev="Media Types">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</title>
1931    <author initials="N." surname="Freed" fullname="Ned Freed">
1932      <organization>Innosoft International, Inc.</organization>
1933      <address><email>ned@innosoft.com</email></address>
1934    </author>
1935    <author initials="N." surname="Borenstein" fullname="Nathaniel S. Borenstein">
1936      <organization>First Virtual Holdings</organization>
1937      <address><email>nsb@nsb.fv.com</email></address>
1938    </author>
1939    <date month="November" year="1996"/>
1940  </front>
1941  <seriesInfo name="RFC" value="2046"/>
1942</reference>
1943
1944<reference anchor="RFC2119">
1945  <front>
1946    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
1947    <author initials="S." surname="Bradner" fullname="Scott Bradner">
1948      <organization>Harvard University</organization>
1949      <address><email>sob@harvard.edu</email></address>
1950    </author>
1951    <date month="March" year="1997"/>
1952  </front>
1953  <seriesInfo name="BCP" value="14"/>
1954  <seriesInfo name="RFC" value="2119"/>
1955</reference>
1956
1957<reference anchor='RFC4647'>
1958  <front>
1959    <title>Matching of Language Tags</title>
1960    <author initials='A.' surname='Phillips' fullname='Addison Phillips' role="editor">
1961      <organization>Yahoo! Inc.</organization>
1962      <address><email>addison@inter-locale.com</email></address>
1963    </author>
1964    <author initials='M.' surname='Davis' fullname='Mark Davis' role="editor">
1965      <organization>Google</organization>
1966      <address><email>mark.davis@macchiato.com</email></address>
1967    </author>
1968    <date year='2006' month='September' />
1969  </front>
1970  <seriesInfo name='BCP' value='47' />
1971  <seriesInfo name='RFC' value='4647' />
1972</reference>
1973
1974<reference anchor="RFC5234">
1975  <front>
1976    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
1977    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
1978      <organization>Brandenburg InternetWorking</organization>
1979      <address>
1980        <email>dcrocker@bbiw.net</email>
1981      </address> 
1982    </author>
1983    <author initials="P." surname="Overell" fullname="Paul Overell">
1984      <organization>THUS plc.</organization>
1985      <address>
1986        <email>paul.overell@thus.net</email>
1987      </address>
1988    </author>
1989    <date month="January" year="2008"/>
1990  </front>
1991  <seriesInfo name="STD" value="68"/>
1992  <seriesInfo name="RFC" value="5234"/>
1993</reference>
1994
1995<reference anchor='RFC5646'>
1996  <front>
1997    <title>Tags for Identifying Languages</title>
1998    <author initials='A.' surname='Phillips' fullname='Addison Phillips' role='editor'>
1999      <organization>Lab126</organization>
2000      <address><email>addison@inter-locale.com</email></address>
2001    </author>
2002    <author initials='M.' surname='Davis' fullname='Mark Davis' role='editor'>
2003      <organization>Google</organization>
2004      <address><email>mark.davis@google.com</email></address>
2005    </author>
2006    <date month='September' year='2009' />
2007  </front>
2008  <seriesInfo name='BCP' value='47' />
2009  <seriesInfo name='RFC' value='5646' />
2010</reference>
2011
2012</references>
2013
2014<references title="Informative References">
2015
2016<reference anchor="RFC1945">
2017  <front>
2018    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
2019    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2020      <organization>MIT, Laboratory for Computer Science</organization>
2021      <address><email>timbl@w3.org</email></address>
2022    </author>
2023    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
2024      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
2025      <address><email>fielding@ics.uci.edu</email></address>
2026    </author>
2027    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
2028      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
2029      <address><email>frystyk@w3.org</email></address>
2030    </author>
2031    <date month="May" year="1996"/>
2032  </front>
2033  <seriesInfo name="RFC" value="1945"/>
2034</reference>
2035
2036<reference anchor="RFC2049">
2037  <front>
2038    <title abbrev="MIME Conformance">Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples</title>
2039    <author initials="N." surname="Freed" fullname="Ned Freed">
2040      <organization>Innosoft International, Inc.</organization>
2041      <address><email>ned@innosoft.com</email></address>
2042    </author>
2043    <author initials="N.S." surname="Borenstein" fullname="Nathaniel S. Borenstein">
2044      <organization>First Virtual Holdings</organization>
2045      <address><email>nsb@nsb.fv.com</email></address>
2046    </author>
2047    <date month="November" year="1996"/>
2048  </front>
2049  <seriesInfo name="RFC" value="2049"/>
2050</reference>
2051
2052<reference anchor="RFC2068">
2053  <front>
2054    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
2055    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
2056      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
2057      <address><email>fielding@ics.uci.edu</email></address>
2058    </author>
2059    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2060      <organization>MIT Laboratory for Computer Science</organization>
2061      <address><email>jg@w3.org</email></address>
2062    </author>
2063    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2064      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
2065      <address><email>mogul@wrl.dec.com</email></address>
2066    </author>
2067    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
2068      <organization>MIT Laboratory for Computer Science</organization>
2069      <address><email>frystyk@w3.org</email></address>
2070    </author>
2071    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2072      <organization>MIT Laboratory for Computer Science</organization>
2073      <address><email>timbl@w3.org</email></address>
2074    </author>
2075    <date month="January" year="1997"/>
2076  </front>
2077  <seriesInfo name="RFC" value="2068"/>
2078</reference>
2079
2080<reference anchor="RFC2076">
2081  <front>
2082    <title abbrev="Internet Message Headers">Common Internet Message Headers</title>
2083    <author initials="J." surname="Palme" fullname="Jacob Palme">
2084      <organization>Stockholm University/KTH</organization>
2085      <address><email>jpalme@dsv.su.se</email></address>
2086    </author>
2087    <date month="February" year="1997"/>
2088  </front>
2089  <seriesInfo name="RFC" value="2076"/>
2090</reference>
2091
2092<reference anchor="RFC2277">
2093  <front>
2094    <title abbrev="Charset Policy">IETF Policy on Character Sets and Languages</title>
2095    <author initials="H.T." surname="Alvestrand" fullname="Harald Tveit Alvestrand">
2096      <organization>UNINETT</organization>
2097      <address><email>Harald.T.Alvestrand@uninett.no</email></address>
2098    </author>
2099    <date month="January" year="1998"/>
2100  </front>
2101  <seriesInfo name="BCP" value="18"/>
2102  <seriesInfo name="RFC" value="2277"/>
2103</reference>
2104
2105<reference anchor='RFC2295'>
2106  <front>
2107    <title abbrev='HTTP Content Negotiation'>Transparent Content Negotiation in HTTP</title>
2108    <author initials='K.' surname='Holtman' fullname='Koen Holtman'>
2109      <organization>Technische Universiteit Eindhoven</organization>
2110      <address>
2111        <email>koen@win.tue.nl</email>
2112      </address>
2113    </author>
2114    <author initials='A.H.' surname='Mutz' fullname='Andrew H. Mutz'>
2115      <organization>Hewlett-Packard Company</organization>
2116      <address>
2117        <email>mutz@hpl.hp.com</email>
2118      </address>
2119    </author>
2120    <date year='1998' month='March'/>
2121  </front>
2122  <seriesInfo name='RFC' value='2295'/>
2123</reference>
2124
2125<reference anchor="RFC2388">
2126  <front>
2127    <title abbrev="multipart/form-data">Returning Values from Forms:  multipart/form-data</title>
2128    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2129      <organization>Xerox Palo Alto Research Center</organization>
2130      <address><email>masinter@parc.xerox.com</email></address>
2131    </author>
2132    <date year="1998" month="August"/>
2133  </front>
2134  <seriesInfo name="RFC" value="2388"/>
2135</reference>
2136
2137<reference anchor="RFC2557">
2138  <front>
2139    <title abbrev="MIME Encapsulation of Aggregate Documents">MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)</title>
2140    <author initials="F." surname="Palme" fullname="Jacob Palme">
2141      <organization>Stockholm University and KTH</organization>
2142      <address><email>jpalme@dsv.su.se</email></address>
2143    </author>
2144    <author initials="A." surname="Hopmann" fullname="Alex Hopmann">
2145      <organization>Microsoft Corporation</organization>
2146      <address><email>alexhop@microsoft.com</email></address>
2147    </author>
2148    <author initials="N." surname="Shelness" fullname="Nick Shelness">
2149      <organization>Lotus Development Corporation</organization>
2150      <address><email>Shelness@lotus.com</email></address>
2151    </author>
2152    <author initials="E." surname="Stefferud" fullname="Einar Stefferud">
2153      <address><email>stef@nma.com</email></address>
2154    </author>
2155    <date year="1999" month="March"/>
2156  </front>
2157  <seriesInfo name="RFC" value="2557"/>
2158</reference>
2159
2160<reference anchor="RFC2616">
2161  <front>
2162    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
2163    <author initials="R." surname="Fielding" fullname="R. Fielding">
2164      <organization>University of California, Irvine</organization>
2165      <address><email>fielding@ics.uci.edu</email></address>
2166    </author>
2167    <author initials="J." surname="Gettys" fullname="J. Gettys">
2168      <organization>W3C</organization>
2169      <address><email>jg@w3.org</email></address>
2170    </author>
2171    <author initials="J." surname="Mogul" fullname="J. Mogul">
2172      <organization>Compaq Computer Corporation</organization>
2173      <address><email>mogul@wrl.dec.com</email></address>
2174    </author>
2175    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
2176      <organization>MIT Laboratory for Computer Science</organization>
2177      <address><email>frystyk@w3.org</email></address>
2178    </author>
2179    <author initials="L." surname="Masinter" fullname="L. Masinter">
2180      <organization>Xerox Corporation</organization>
2181      <address><email>masinter@parc.xerox.com</email></address>
2182    </author>
2183    <author initials="P." surname="Leach" fullname="P. Leach">
2184      <organization>Microsoft Corporation</organization>
2185      <address><email>paulle@microsoft.com</email></address>
2186    </author>
2187    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
2188      <organization>W3C</organization>
2189      <address><email>timbl@w3.org</email></address>
2190    </author>
2191    <date month="June" year="1999"/>
2192  </front>
2193  <seriesInfo name="RFC" value="2616"/>
2194</reference>
2195
2196<reference anchor="RFC3629">
2197  <front>
2198    <title>UTF-8, a transformation format of ISO 10646</title>
2199    <author initials="F." surname="Yergeau" fullname="F. Yergeau">
2200      <organization>Alis Technologies</organization>
2201      <address><email>fyergeau@alis.com</email></address>
2202    </author>
2203    <date month="November" year="2003"/>
2204  </front>
2205  <seriesInfo name="STD" value="63"/>
2206  <seriesInfo name="RFC" value="3629"/>
2207</reference>
2208
2209<reference anchor='RFC3864'>
2210  <front>
2211    <title>Registration Procedures for Message Header Fields</title>
2212    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
2213      <organization>Nine by Nine</organization>
2214      <address><email>GK-IETF@ninebynine.org</email></address>
2215    </author>
2216    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
2217      <organization>BEA Systems</organization>
2218      <address><email>mnot@pobox.com</email></address>
2219    </author>
2220    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
2221      <organization>HP Labs</organization>
2222      <address><email>JeffMogul@acm.org</email></address>
2223    </author>
2224    <date year='2004' month='September' />
2225  </front>
2226  <seriesInfo name='BCP' value='90' />
2227  <seriesInfo name='RFC' value='3864' />
2228</reference>
2229
2230<reference anchor="RFC4288">
2231  <front>
2232    <title>Media Type Specifications and Registration Procedures</title>
2233    <author initials="N." surname="Freed" fullname="N. Freed">
2234      <organization>Sun Microsystems</organization>
2235      <address>
2236        <email>ned.freed@mrochek.com</email>
2237      </address>
2238    </author>
2239    <author initials="J." surname="Klensin" fullname="J. Klensin">
2240      <address>
2241        <email>klensin+ietf@jck.com</email>
2242      </address>
2243    </author>
2244    <date year="2005" month="December"/>
2245  </front>
2246  <seriesInfo name="BCP" value="13"/>
2247  <seriesInfo name="RFC" value="4288"/>
2248</reference>
2249
2250<reference anchor='RFC5226'>
2251  <front>
2252    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
2253    <author initials='T.' surname='Narten' fullname='T. Narten'>
2254      <organization>IBM</organization>
2255      <address><email>narten@us.ibm.com</email></address>
2256    </author>
2257    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
2258      <organization>Google</organization>
2259      <address><email>Harald@Alvestrand.no</email></address>
2260    </author>
2261    <date year='2008' month='May' />
2262  </front>
2263  <seriesInfo name='BCP' value='26' />
2264  <seriesInfo name='RFC' value='5226' />
2265</reference>
2266
2267<reference anchor="RFC5322">
2268  <front>
2269    <title>Internet Message Format</title>
2270    <author initials="P." surname="Resnick" fullname="P. Resnick">
2271      <organization>Qualcomm Incorporated</organization>
2272    </author>
2273    <date year="2008" month="October"/>
2274  </front> 
2275  <seriesInfo name="RFC" value="5322"/>
2276</reference>
2277
2278<reference anchor="RFC6151">
2279  <front>
2280    <title>Updated Security Considerations for the MD5 Message-Digest and the HMAC-MD5 Algorithms</title>
2281    <author initials="S." surname="Turner" fullname="S. Turner"/>
2282    <author initials="L." surname="Chen" fullname="L. Chen"/>
2283    <date year="2011" month="March" />
2284        </front>
2285  <seriesInfo name="RFC" value="6151" />
2286</reference>
2287
2288<reference anchor='BCP97'>
2289  <front>
2290    <title>Handling Normative References to Standards-Track Documents</title>
2291    <author initials='J.' surname='Klensin' fullname='J. Klensin'>
2292      <address>
2293        <email>klensin+ietf@jck.com</email>
2294      </address>
2295    </author>
2296    <author initials='S.' surname='Hartman' fullname='S. Hartman'>
2297      <organization>MIT</organization>
2298      <address>
2299        <email>hartmans-ietf@mit.edu</email>
2300      </address>
2301    </author>
2302    <date year='2007' month='June' />
2303  </front>
2304  <seriesInfo name='BCP' value='97' />
2305  <seriesInfo name='RFC' value='4897' />
2306</reference>
2307
2308<reference anchor="draft-ietf-httpbis-content-disp">
2309        <front>
2310    <title abbrev="Content-Disposition in HTTP">Use of the Content-Disposition Header Field
2311    in the Hypertext Transfer Protocol (HTTP)</title>
2312    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke">
2313      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2314      <address>
2315        <email>julian.reschke@greenbytes.de</email>     
2316      </address>
2317    </author>
2318    <date month="March" year="2011" day="28"/>
2319  </front>
2320  <seriesInfo name='Internet-Draft' value='draft-ietf-httpbis-content-disp-09' />
2321</reference>
2322
2323</references>
2324
2325<section title="Differences between HTTP and MIME" anchor="differences.between.http.and.mime">
2326<t>
2327   HTTP/1.1 uses many of the constructs defined for Internet Mail (<xref target="RFC5322"/>) and the Multipurpose Internet Mail Extensions (MIME <xref target="RFC2045"/>) to
2328   allow a message-body to be transmitted in an open variety of
2329   representations and with extensible mechanisms. However, RFC 2045
2330   discusses mail, and HTTP has a few features that are different from
2331   those described in MIME. These differences were carefully chosen
2332   to optimize performance over binary connections, to allow greater
2333   freedom in the use of new media types, to make date comparisons
2334   easier, and to acknowledge the practice of some early HTTP servers
2335   and clients.
2336</t>
2337<t>
2338   This appendix describes specific areas where HTTP differs from MIME.
2339   Proxies and gateways to strict MIME environments &SHOULD; be
2340   aware of these differences and provide the appropriate conversions
2341   where necessary. Proxies and gateways from MIME environments to HTTP
2342   also need to be aware of the differences because some conversions
2343   might be required.
2344</t>
2345
2346<section title="MIME-Version" anchor="mime-version">
2347  <iref primary="true" item="MIME-Version header field" x:for-anchor=""/>
2348  <iref primary="true" item="Header Fields" subitem="MIME-Version" x:for-anchor=""/>
2349  <x:anchor-alias value="MIME-Version"/>
2350<t>
2351   HTTP is not a MIME-compliant protocol. However, HTTP/1.1 messages &MAY;
2352   include a single MIME-Version header field to indicate what
2353   version of the MIME protocol was used to construct the message. Use
2354   of the MIME-Version header field indicates that the message is in
2355   full compliance with the MIME protocol (as defined in <xref target="RFC2045"/>).
2356   Proxies/gateways are responsible for ensuring full compliance (where
2357   possible) when exporting HTTP messages to strict MIME environments.
2358</t>
2359<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="MIME-Version"/>
2360  <x:ref>MIME-Version</x:ref> = 1*<x:ref>DIGIT</x:ref> "." 1*<x:ref>DIGIT</x:ref>
2361</artwork></figure>
2362<t>
2363   MIME version "1.0" is the default for use in HTTP/1.1. However,
2364   HTTP/1.1 message parsing and semantics are defined by this document
2365   and not the MIME specification.
2366</t>
2367</section>
2368
2369<section title="Conversion to Canonical Form" anchor="conversion.to.canonical.form">
2370<t>
2371   MIME requires that an Internet mail body-part be converted to
2372   canonical form prior to being transferred, as described in <xref target="RFC2049" x:fmt="of" x:sec="4"/>.
2373   <xref target="canonicalization.and.text.defaults"/> of this document describes the forms
2374   allowed for subtypes of the "text" media type when transmitted over
2375   HTTP. <xref target="RFC2046"/> requires that content with a type of "text" represent
2376   line breaks as CRLF and forbids the use of CR or LF outside of line
2377   break sequences. HTTP allows CRLF, bare CR, and bare LF to indicate a
2378   line break within text content when a message is transmitted over
2379   HTTP.
2380</t>
2381<t>
2382   Where it is possible, a proxy or gateway from HTTP to a strict MIME
2383   environment &SHOULD; translate all line breaks within the text media
2384   types described in <xref target="canonicalization.and.text.defaults"/>
2385   of this document to the RFC 2049
2386   canonical form of CRLF. Note, however, that this might be complicated
2387   by the presence of a Content-Encoding and by the fact that HTTP
2388   allows the use of some character encodings which do not use octets 13 and
2389   10 to represent CR and LF, respectively, as is the case for some multi-byte
2390   character encodings.
2391</t>
2392<t>
2393   Conversion will break any cryptographic
2394   checksums applied to the original content unless the original content
2395   is already in canonical form. Therefore, the canonical form is
2396   recommended for any content that uses such checksums in HTTP.
2397</t>
2398</section>
2399
2400
2401<section title="Conversion of Date Formats" anchor="conversion.of.date.formats">
2402<t>
2403   HTTP/1.1 uses a restricted set of date formats (&full-date;) to
2404   simplify the process of date comparison. Proxies and gateways from
2405   other protocols &SHOULD; ensure that any Date header field present in a
2406   message conforms to one of the HTTP/1.1 formats and rewrite the date
2407   if necessary.
2408</t>
2409</section>
2410
2411<section title="Introduction of Content-Encoding" anchor="introduction.of.content-encoding">
2412<t>
2413   MIME does not include any concept equivalent to HTTP/1.1's
2414   Content-Encoding header field. Since this acts as a modifier on the
2415   media type, proxies and gateways from HTTP to MIME-compliant
2416   protocols &MUST; either change the value of the Content-Type header
2417   field or decode the representation before forwarding the message. (Some
2418   experimental applications of Content-Type for Internet mail have used
2419   a media-type parameter of ";conversions=&lt;content-coding&gt;" to perform
2420   a function equivalent to Content-Encoding. However, this parameter is
2421   not part of the MIME standards).
2422</t>
2423</section>
2424
2425<section title="No Content-Transfer-Encoding" anchor="no.content-transfer-encoding">
2426<t>
2427   HTTP does not use the Content-Transfer-Encoding field of MIME.
2428   Proxies and gateways from MIME-compliant protocols to HTTP &MUST;
2429   remove any Content-Transfer-Encoding
2430   prior to delivering the response message to an HTTP client.
2431</t>
2432<t>
2433   Proxies and gateways from HTTP to MIME-compliant protocols are
2434   responsible for ensuring that the message is in the correct format
2435   and encoding for safe transport on that protocol, where "safe
2436   transport" is defined by the limitations of the protocol being used.
2437   Such a proxy or gateway &SHOULD; label the data with an appropriate
2438   Content-Transfer-Encoding if doing so will improve the likelihood of
2439   safe transport over the destination protocol.
2440</t>
2441</section>
2442
2443<section title="Introduction of Transfer-Encoding" anchor="introduction.of.transfer-encoding">
2444<t>
2445   HTTP/1.1 introduces the Transfer-Encoding header field (&header-transfer-encoding;).
2446   Proxies/gateways &MUST; remove any transfer-coding prior to
2447   forwarding a message via a MIME-compliant protocol.
2448</t>
2449</section>
2450
2451<section title="MHTML and Line Length Limitations" anchor="mhtml.line.length">
2452<t>
2453   HTTP implementations which share code with MHTML <xref target="RFC2557"/> implementations
2454   need to be aware of MIME line length limitations. Since HTTP does not
2455   have this limitation, HTTP does not fold long lines. MHTML messages
2456   being transported by HTTP follow all conventions of MHTML, including
2457   line length limitations and folding, canonicalization, etc., since
2458   HTTP transports all message-bodies as payload (see <xref target="multipart.types"/>) and
2459   does not interpret the content or any MIME header lines that might be
2460   contained therein.
2461</t>
2462</section>
2463</section>
2464
2465<section title="Additional Features" anchor="additional.features">
2466<t>
2467   <xref target="RFC1945"/> and <xref target="RFC2068"/> document protocol elements used by some
2468   existing HTTP implementations, but not consistently and correctly
2469   across most HTTP/1.1 applications. Implementors are advised to be
2470   aware of these features, but cannot rely upon their presence in, or
2471   interoperability with, other HTTP/1.1 applications. Some of these
2472   describe proposed experimental features, and some describe features
2473   that experimental deployment found lacking that are now addressed in
2474   the base HTTP/1.1 specification.
2475</t>
2476<t>
2477   A number of other header fields, such as Content-Disposition and Title,
2478   from SMTP and MIME are also often implemented (see <xref target="draft-ietf-httpbis-content-disp"/>
2479         and <xref target="RFC2076"/>).
2480</t>
2481</section>
2482
2483<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
2484<t>
2485  Clarify contexts that charset is used in.
2486  (<xref target="character.sets"/>)
2487</t>
2488<t>
2489  Remove the default character encoding for text media types; the default
2490  now is whatever the media type definition says.
2491  (<xref target="canonicalization.and.text.defaults"/>)
2492</t>
2493<t>
2494  Change ABNF productions for header fields to only define the field value.
2495  (<xref target="header.fields"/>)
2496</t>
2497<t>
2498        Remove definition of Content-MD5 header field because it was inconsistently
2499        implemented with respect to partial responses, and also because of known
2500        deficiencies in the hash algorithm itself (see <xref target="RFC6151"/> for details).
2501  (<xref target="header.fields"/>)
2502</t>
2503<t>
2504  Remove ISO-8859-1 special-casing in Accept-Charset.
2505  (<xref target="header.accept-charset"/>)
2506</t>
2507<t>
2508  Remove base URI setting semantics for Content-Location due to poor
2509  implementation support, which was caused by too many broken servers emitting
2510  bogus Content-Location header fields, and also the potentially undesirable effect
2511  of potentially breaking relative links in content-negotiated resources.
2512  (<xref target="header.content-location"/>)
2513</t>
2514<t>
2515        Remove discussion of Content-Disposition header field, it is now defined
2516        by <xref target="draft-ietf-httpbis-content-disp"/>.
2517  (<xref target="additional.features"/>)
2518</t>
2519<t>
2520  Remove reference to non-existant identity transfer-coding value tokens.
2521  (<xref target="no.content-transfer-encoding"/>)
2522</t>
2523</section>
2524
2525<?BEGININC p3-payload.abnf-appendix ?>
2526<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
2527<figure>
2528<artwork type="abnf" name="p3-payload.parsed-abnf">
2529<x:ref>Accept</x:ref> = [ ( "," / ( media-range [ accept-params ] ) ) *( OWS "," [
2530 OWS media-range [ accept-params ] ] ) ]
2531<x:ref>Accept-Charset</x:ref> = *( "," OWS ) ( charset / "*" ) [ OWS ";" OWS "q="
2532 qvalue ] *( OWS "," [ OWS ( charset / "*" ) [ OWS ";" OWS "q="
2533 qvalue ] ] )
2534<x:ref>Accept-Encoding</x:ref> = [ ( "," / ( codings [ OWS ";" OWS "q=" qvalue ] ) )
2535 *( OWS "," [ OWS codings [ OWS ";" OWS "q=" qvalue ] ] ) ]
2536<x:ref>Accept-Language</x:ref> = *( "," OWS ) language-range [ OWS ";" OWS "q="
2537 qvalue ] *( OWS "," [ OWS language-range [ OWS ";" OWS "q=" qvalue ]
2538 ] )
2539
2540<x:ref>Content-Encoding</x:ref> = *( "," OWS ) content-coding *( OWS "," [ OWS
2541 content-coding ] )
2542<x:ref>Content-Language</x:ref> = *( "," OWS ) language-tag *( OWS "," [ OWS
2543 language-tag ] )
2544<x:ref>Content-Location</x:ref> = absolute-URI / partial-URI
2545<x:ref>Content-Type</x:ref> = media-type
2546
2547<x:ref>MIME-Version</x:ref> = 1*DIGIT "." 1*DIGIT
2548
2549<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
2550
2551<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
2552<x:ref>accept-ext</x:ref> = OWS ";" OWS token [ "=" word ]
2553<x:ref>accept-params</x:ref> = OWS ";" OWS "q=" qvalue *accept-ext
2554<x:ref>attribute</x:ref> = token
2555
2556<x:ref>charset</x:ref> = token
2557<x:ref>codings</x:ref> = ( content-coding / "*" )
2558<x:ref>content-coding</x:ref> = token
2559
2560<x:ref>language-range</x:ref> = &lt;language-range, defined in [RFC4647], Section 2.1&gt;
2561<x:ref>language-tag</x:ref> = &lt;Language-Tag, defined in [RFC5646], Section 2.1&gt;
2562
2563<x:ref>media-range</x:ref> = ( "*/*" / ( type "/*" ) / ( type "/" subtype ) ) *( OWS
2564 ";" OWS parameter )
2565<x:ref>media-type</x:ref> = type "/" subtype *( OWS ";" OWS parameter )
2566
2567<x:ref>parameter</x:ref> = attribute "=" value
2568<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
2569
2570<x:ref>qvalue</x:ref> = &lt;qvalue, defined in [Part1], Section 6.4&gt;
2571
2572<x:ref>subtype</x:ref> = token
2573
2574<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
2575<x:ref>type</x:ref> = token
2576
2577<x:ref>value</x:ref> = word
2578
2579<x:ref>word</x:ref> = &lt;word, defined in [Part1], Section 1.2.2&gt;
2580</artwork>
2581</figure>
2582<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
2583; Accept defined but not used
2584; Accept-Charset defined but not used
2585; Accept-Encoding defined but not used
2586; Accept-Language defined but not used
2587; Content-Encoding defined but not used
2588; Content-Language defined but not used
2589; Content-Location defined but not used
2590; Content-Type defined but not used
2591; MIME-Version defined but not used
2592</artwork></figure></section>
2593<?ENDINC p3-payload.abnf-appendix ?>
2594
2595<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
2596
2597<section title="Since RFC 2616">
2598<t>
2599  Extracted relevant partitions from <xref target="RFC2616"/>.
2600</t>
2601</section>
2602
2603<section title="Since draft-ietf-httpbis-p3-payload-00">
2604<t>
2605  Closed issues:
2606  <list style="symbols"> 
2607    <t>
2608      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/8"/>:
2609      "Media Type Registrations"
2610      (<eref target="http://purl.org/NET/http-errata#media-reg"/>)
2611    </t>
2612    <t>
2613      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/14"/>:
2614      "Clarification regarding quoting of charset values"
2615      (<eref target="http://purl.org/NET/http-errata#charactersets"/>)
2616    </t>
2617    <t>
2618      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/16"/>:
2619      "Remove 'identity' token references"
2620      (<eref target="http://purl.org/NET/http-errata#identity"/>)
2621    </t>
2622    <t>
2623      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/25"/>:
2624      "Accept-Encoding BNF"
2625    </t>
2626    <t>
2627      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
2628      "Normative and Informative references"
2629    </t>
2630    <t>
2631      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/46"/>:
2632      "RFC1700 references"
2633    </t>
2634    <t>
2635      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/55"/>:
2636      "Updating to RFC4288"
2637    </t>
2638    <t>
2639      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
2640      "Informative references"
2641    </t>
2642    <t>
2643      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/66"/>:
2644      "ISO-8859-1 Reference"
2645    </t>
2646    <t>
2647      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/68"/>:
2648      "Encoding References Normative"
2649    </t>
2650    <t>
2651      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/86"/>:
2652      "Normative up-to-date references"
2653    </t>
2654  </list>
2655</t>
2656</section>
2657
2658<section title="Since draft-ietf-httpbis-p3-payload-01">
2659<t>
2660  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
2661  <list style="symbols"> 
2662    <t>
2663      Add explicit references to BNF syntax and rules imported from other parts of the specification.
2664    </t>
2665  </list>
2666</t>
2667</section>
2668
2669<section title="Since draft-ietf-httpbis-p3-payload-02" anchor="changes.since.02">
2670<t>
2671  Closed issues:
2672  <list style="symbols"> 
2673    <t>
2674      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/67"/>:
2675      "Quoting Charsets"
2676    </t>
2677    <t>
2678      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
2679      "Classification for Allow header"
2680    </t>
2681    <t>
2682      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/115"/>:
2683      "missing default for qvalue in description of Accept-Encoding"
2684    </t>
2685  </list>
2686</t>
2687<t>
2688  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
2689  <list style="symbols"> 
2690    <t>
2691      Reference RFC 3984, and update header field registrations for headers defined
2692      in this document.
2693    </t>
2694  </list>
2695</t>
2696</section>
2697
2698<section title="Since draft-ietf-httpbis-p3-payload-03" anchor="changes.since.03">
2699<t>
2700  Closed issues:
2701  <list style="symbols"> 
2702    <t>
2703      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/67"/>:
2704      "Quoting Charsets"
2705    </t>
2706    <t>
2707      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/113"/>:
2708      "language tag matching (Accept-Language) vs RFC4647"
2709    </t>
2710    <t>
2711      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/121"/>:
2712      "RFC 1806 has been replaced by RFC2183"
2713    </t>
2714  </list>
2715</t>
2716<t>
2717  Other changes:
2718  <list style="symbols"> 
2719    <t>
2720      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/68"/>:
2721      "Encoding References Normative" &mdash; rephrase the annotation and reference
2722      <xref target="BCP97"/>.
2723    </t>
2724  </list>
2725</t>
2726 </section>
2727
2728<section title="Since draft-ietf-httpbis-p3-payload-04" anchor="changes.since.04">
2729<t>
2730  Closed issues:
2731  <list style="symbols"> 
2732    <t>
2733      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
2734      "RFC 2822 is updated by RFC 5322"
2735    </t>
2736  </list>
2737</t>
2738<t>
2739  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
2740  <list style="symbols"> 
2741    <t>
2742      Use "/" instead of "|" for alternatives.
2743    </t>
2744    <t>
2745      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
2746      whitespace ("OWS") and required whitespace ("RWS").
2747    </t>
2748    <t>
2749      Rewrite ABNFs to spell out whitespace rules, factor out
2750      header field value format definitions.
2751    </t>
2752  </list>
2753</t>
2754</section>
2755
2756<section title="Since draft-ietf-httpbis-p3-payload-05" anchor="changes.since.05">
2757<t>
2758  Closed issues:
2759  <list style="symbols"> 
2760    <t>
2761      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/118"/>:
2762      "Join "Differences Between HTTP Entities and RFC 2045 Entities"?"
2763    </t>
2764  </list>
2765</t>
2766<t>
2767  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
2768  <list style="symbols"> 
2769    <t>
2770      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
2771    </t>
2772  </list>
2773</t>
2774<t>
2775  Other changes:
2776  <list style="symbols"> 
2777    <t>
2778      Move definition of quality values into Part 1.
2779    </t>
2780  </list>
2781</t>
2782</section>
2783
2784<section title="Since draft-ietf-httpbis-p3-payload-06" anchor="changes.since.06">
2785<t>
2786  Closed issues:
2787  <list style="symbols"> 
2788    <t>
2789      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/80"/>:
2790      "Content-Location isn't special"
2791    </t>
2792    <t>
2793      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/155"/>:
2794      "Content Sniffing"
2795    </t>
2796  </list>
2797</t>
2798</section>
2799
2800<section title="Since draft-ietf-httpbis-p3-payload-07" anchor="changes.since.07">
2801<t>
2802  Closed issues:
2803  <list style="symbols"> 
2804    <t>
2805      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/13"/>:
2806      "Updated reference for language tags"
2807    </t>
2808    <t>
2809      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
2810      "Clarify rules for determining what entities a response carries"
2811    </t>
2812    <t>
2813      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/154"/>:
2814      "Content-Location base-setting problems"
2815    </t>
2816    <t>
2817      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/155"/>:
2818      "Content Sniffing"
2819    </t>
2820    <t>
2821      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/188"/>:
2822      "pick IANA policy (RFC5226) for Transfer Coding / Content Coding"
2823    </t>
2824    <t>
2825      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/189"/>:
2826      "move definitions of gzip/deflate/compress to part 1"
2827    </t>
2828  </list>
2829</t>
2830<t>
2831  Partly resolved issues:
2832  <list style="symbols"> 
2833    <t>
2834      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/148"/>:
2835      "update IANA requirements wrt Transfer-Coding values" (add the
2836      IANA Considerations subsection)
2837    </t>
2838    <t>
2839      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/149"/>:
2840      "update IANA requirements wrt Content-Coding values" (add the
2841      IANA Considerations subsection)
2842    </t>
2843  </list>
2844</t>
2845</section>
2846
2847<section title="Since draft-ietf-httpbis-p3-payload-08" anchor="changes.since.08">
2848<t>
2849  Closed issues:
2850  <list style="symbols"> 
2851    <t>
2852      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/81"/>:
2853      "Content Negotiation for media types"
2854    </t>
2855    <t>
2856      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/181"/>:
2857      "Accept-Language: which RFC4647 filtering?"
2858    </t>
2859  </list>
2860</t>
2861</section>
2862
2863<section title="Since draft-ietf-httpbis-p3-payload-09" anchor="changes.since.09">
2864<t>
2865  Closed issues:
2866  <list style="symbols"> 
2867    <t>
2868      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/122"/>:
2869      "MIME-Version not listed in P1, general header fields"
2870    </t>
2871    <t>
2872      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/143"/>:
2873      "IANA registry for content/transfer encodings"
2874    </t>
2875    <t>
2876      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/155"/>:
2877      "Content Sniffing"
2878    </t>
2879    <t>
2880      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/200"/>:
2881      "use of term "word" when talking about header structure"
2882    </t>
2883  </list>
2884</t>
2885<t>
2886  Partly resolved issues:
2887  <list style="symbols"> 
2888    <t>
2889      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
2890      "Term for the requested resource's URI"
2891    </t>
2892  </list>
2893</t>
2894</section>
2895
2896<section title="Since draft-ietf-httpbis-p3-payload-10" anchor="changes.since.10">
2897<t>
2898  Closed issues:
2899  <list style="symbols"> 
2900    <t>
2901      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
2902      "Clarify 'Requested Variant'"
2903    </t>
2904    <t>
2905      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/80"/>:
2906      "Content-Location isn't special"
2907    </t>
2908    <t>
2909      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/90"/>:
2910      "Delimiting messages with multipart/byteranges"
2911    </t>
2912    <t>
2913      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
2914      "Clarify entity / representation / variant terminology"
2915    </t>
2916    <t>
2917      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/136"/>:
2918      "confusing req. language for Content-Location"
2919    </t>
2920    <t>
2921      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/167"/>:
2922      "Content-Location on 304 responses"
2923    </t>
2924    <t>
2925      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/183"/>:
2926      "'requested resource' in content-encoding definition"
2927    </t>
2928    <t>
2929      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
2930      "consider removing the 'changes from 2068' sections"
2931    </t>
2932  </list>
2933</t>
2934<t>
2935  Partly resolved issues:
2936  <list style="symbols"> 
2937    <t>
2938      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/178"/>:
2939      "Content-MD5 and partial responses"
2940    </t>
2941  </list>
2942</t>
2943</section>
2944
2945<section title="Since draft-ietf-httpbis-p3-payload-11" anchor="changes.since.11">
2946<t>
2947  Closed issues:
2948  <list style="symbols"> 
2949    <t>
2950      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/123"/>:
2951      "Factor out Content-Disposition"
2952    </t>
2953  </list>
2954</t>
2955</section>
2956
2957<section title="Since draft-ietf-httpbis-p3-payload-12" anchor="changes.since.12">
2958<t>
2959  Closed issues:
2960  <list style="symbols"> 
2961    <t>
2962      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/224"/>:
2963      "Header Classification"
2964    </t>
2965    <t>
2966      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>:
2967      "untangle ABNFs for header fields"
2968    </t>
2969    <t>
2970      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/277"/>:
2971      "potentially misleading MAY in media-type def"
2972    </t>
2973  </list>
2974</t>
2975</section>
2976
2977<section title="Since draft-ietf-httpbis-p3-payload-13" anchor="changes.since.13">
2978<t>
2979  Closed issues:
2980  <list style="symbols"> 
2981    <t>
2982      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/20"/>:
2983      "Default charsets for text media types"
2984    </t>
2985    <t>
2986      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/178"/>:
2987      "Content-MD5 and partial responses"
2988    </t>
2989    <t>
2990      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>:
2991      "untangle ABNFs for header fields"
2992    </t>
2993    <t>
2994      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/281"/>:
2995      "confusing undefined parameter in media range example"
2996    </t>
2997  </list>
2998</t>
2999</section>
3000
3001</section>
3002
3003</back>
3004</rfc>
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