source: draft-ietf-httpbis/latest/p3-payload.xml @ 1544

Last change on this file since 1544 was 1544, checked in by fielding@…, 8 years ago

For consistency and readability, do not hyphenate "message body"
unless we are referring to the message-body ABNF rule.

  • Property svn:eol-style set to native
  • Property svn:mime-type set to text/xml
File size: 125.7 KB
[29]1<?xml version="1.0" encoding="utf-8"?>
[101]2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
[8]3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns=''>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns=''>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns=''>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns=''>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns=''>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns=''>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns=''>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns=''>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns=''>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns=''>SHOULD NOT</bcp14>">
[29]14  <!ENTITY ID-VERSION "latest">
[1522]15  <!ENTITY ID-MONTH "February">
[1497]16  <!ENTITY ID-YEAR "2012">
[1101]17  <!ENTITY mdash "&#8212;">
[1454]18  <!ENTITY architecture             "<xref target='Part1' x:rel='#architecture' xmlns:x=''/>">
[424]19  <!ENTITY notation                 "<xref target='Part1' x:rel='#notation' xmlns:x=''/>">
[1518]20  <!ENTITY abnf-extension           "<xref target='Part1' x:rel='#abnf.extension' xmlns:x=''/>">
[1399]21  <!ENTITY acks                     "<xref target='Part1' x:rel='#acks' xmlns:x=''/>">
[1518]22  <!ENTITY whitespace               "<xref target='Part1' x:rel='#whitespace' xmlns:x=''/>">
23  <!ENTITY field-components         "<xref target='Part1' x:rel='#field.components' xmlns:x=''/>">
[115]24  <!ENTITY caching-neg-resp         "<xref target='Part6' x:rel='#caching.negotiated.responses' xmlns:x=''/>">
[31]25  <!ENTITY header-transfer-encoding "<xref target='Part1' x:rel='#header.transfer-encoding' xmlns:x=''/>">
26  <!ENTITY header-content-length    "<xref target='Part1' x:rel='#header.content-length' xmlns:x=''/>">
27  <!ENTITY header-content-range     "<xref target='Part5' x:rel='#header.content-range' xmlns:x=''/>">
28  <!ENTITY header-expires           "<xref target='Part6' x:rel='#header.expires' xmlns:x=''/>">
29  <!ENTITY header-last-modified     "<xref target='Part4' x:rel='#header.last-modified' xmlns:x=''/>">
30  <!ENTITY header-user-agent        "<xref target='Part2' x:rel='#header.user-agent' xmlns:x=''/>">
[115]31  <!ENTITY header-vary              "<xref target='Part6' x:rel='#header.vary' xmlns:x=''/>">
[31]32  <!ENTITY message-body             "<xref target='Part1' x:rel='#message.body' xmlns:x=''/>">
33  <!ENTITY multipart-byteranges     "<xref target='Part5' x:rel='' xmlns:x=''/>">
[1436]34  <!ENTITY http-date                "<xref target='Part2' x:rel='' xmlns:x=''/>">
[457]35  <!ENTITY qvalue                   "<xref target='Part1' x:rel='#quality.values' xmlns:x=''/>">
[374]36  <!ENTITY uri                      "<xref target='Part1' x:rel='#uri' xmlns:x=''/>">
[823]37  <!ENTITY effective-request-uri    "<xref target='Part1' x:rel='#effective.request.uri' xmlns:x=''/>">
[808]38  <!ENTITY compression-codings      "<xref target='Part1' x:rel='#compression.codings' xmlns:x=''/>">
39  <!ENTITY transfer-codings         "<xref target='Part1' x:rel='#transfer.codings' xmlns:x=''/>">
[673]40  <!ENTITY compress-coding          "<xref target='Part1' x:rel='#compress.coding' xmlns:x=''/>">
41  <!ENTITY deflate-coding           "<xref target='Part1' x:rel='#deflate.coding' xmlns:x=''/>">
42  <!ENTITY gzip-coding              "<xref target='Part1' x:rel='#gzip.coding' xmlns:x=''/>">
[716]43  <!ENTITY response-representation  "<xref target='Part2' x:rel='#identifying.response.associated.with.representation' xmlns:x=''/>">
45<?rfc toc="yes" ?>
[29]46<?rfc symrefs="yes" ?>
47<?rfc sortrefs="yes" ?>
[8]48<?rfc compact="yes"?>
49<?rfc subcompact="no" ?>
50<?rfc linkmailto="no" ?>
51<?rfc editing="no" ?>
[203]52<?rfc comments="yes"?>
53<?rfc inline="yes"?>
[799]54<?rfc rfcedstyle="yes"?>
[8]55<?rfc-ext allow-markup-in-artwork="yes" ?>
56<?rfc-ext include-references-in-index="yes" ?>
[1477]57<rfc obsoletes="2616" category="std" x:maturity-level="proposed"
[446]58     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p3-payload-&ID-VERSION;"
[153]59     xmlns:x=''>
[1472]60<x:link rel="prev" basename="p2-semantics"/>
61<x:link rel="next" basename="p4-conditional"/>
[1522]62<x:feedback template="{docname},%20%22{section}%22&amp;body=&lt;{ref}&gt;:"/>
[120]65  <title abbrev="HTTP/1.1, Part 3">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
[29]67  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
[1106]68    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[8]69    <address>
70      <postal>
[1106]71        <street>345 Park Ave</street>
72        <city>San Jose</city>
[8]73        <region>CA</region>
[1106]74        <code>95110</code>
[29]75        <country>USA</country>
[8]76      </postal>
[29]77      <email></email>
78      <uri></uri>
[8]79    </address>
80  </author>
[29]82  <author initials="J." surname="Gettys" fullname="Jim Gettys">
[844]83    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
[8]84    <address>
85      <postal>
[29]86        <street>21 Oak Knoll Road</street>
87        <city>Carlisle</city>
[8]88        <region>MA</region>
[29]89        <code>01741</code>
90        <country>USA</country>
[8]91      </postal>
[844]92      <email></email>
93      <uri></uri>
[8]94    </address>
95  </author>
97  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
[29]98    <organization abbrev="HP">Hewlett-Packard Company</organization>
[8]99    <address>
100      <postal>
[29]101        <street>HP Labs, Large Scale Systems Group</street>
102        <street>1501 Page Mill Road, MS 1177</street>
[8]103        <city>Palo Alto</city>
104        <region>CA</region>
[29]105        <code>94304</code>
106        <country>USA</country>
[8]107      </postal>
[29]108      <email></email>
[8]109    </address>
110  </author>
112  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
[29]113    <organization abbrev="Microsoft">Microsoft Corporation</organization>
[8]114    <address>
115      <postal>
[29]116        <street>1 Microsoft Way</street>
117        <city>Redmond</city>
118        <region>WA</region>
119        <code>98052</code>
120        <country>USA</country>
[8]121      </postal>
[29]122      <email></email>
[8]123    </address>
124  </author>
126  <author initials="L." surname="Masinter" fullname="Larry Masinter">
[1106]127    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[8]128    <address>
129      <postal>
[29]130        <street>345 Park Ave</street>
131        <city>San Jose</city>
[8]132        <region>CA</region>
[29]133        <code>95110</code>
134        <country>USA</country>
[8]135      </postal>
[29]136      <email></email>
137      <uri></uri>
[8]138    </address>
139  </author>
141  <author initials="P." surname="Leach" fullname="Paul J. Leach">
142    <organization abbrev="Microsoft">Microsoft Corporation</organization>
143    <address>
144      <postal>
145        <street>1 Microsoft Way</street>
146        <city>Redmond</city>
147        <region>WA</region>
148        <code>98052</code>
149      </postal>
150      <email></email>
151    </address>
152  </author>
154  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
155    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
156    <address>
157      <postal>
[34]158        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
159        <street>The Stata Center, Building 32</street>
160        <street>32 Vassar Street</street>
[8]161        <city>Cambridge</city>
162        <region>MA</region>
163        <code>02139</code>
[29]164        <country>USA</country>
[8]165      </postal>
166      <email></email>
[34]167      <uri></uri>
[8]168    </address>
169  </author>
[95]171  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
[94]172    <organization abbrev="W3C">World Wide Web Consortium</organization>
173    <address>
174      <postal>
175        <street>W3C / ERCIM</street>
176        <street>2004, rte des Lucioles</street>
177        <city>Sophia-Antipolis</city>
178        <region>AM</region>
179        <code>06902</code>
180        <country>France</country>
181      </postal>
182      <email></email>
183      <uri></uri>
184    </address>
185  </author>
[95]187  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
188    <organization abbrev="greenbytes">greenbytes GmbH</organization>
189    <address>
190      <postal>
191        <street>Hafenweg 16</street>
192        <city>Muenster</city><region>NW</region><code>48155</code>
193        <country>Germany</country>
194      </postal>
[609]195      <phone>+49 251 2807760</phone>
196      <facsimile>+49 251 2807761</facsimile>
197      <email></email>
198      <uri></uri>
[95]199    </address>
200  </author>
[31]202  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
[440]203  <workgroup>HTTPbis Working Group</workgroup>
[1373]207   The Hypertext Transfer Protocol (HTTP) is an application-level protocol for
208   distributed, collaborative, hypertext information systems. HTTP has been in
209   use by the World Wide Web global information initiative since 1990. This
210   document is Part 3 of the seven-part specification that defines the protocol
211   referred to as "HTTP/1.1" and, taken together, obsoletes RFC 2616.
214   Part 3 defines HTTP message content, metadata, and content negotiation.
218<note title="Editorial Note (To be removed by RFC Editor)">
219  <t>
220    Discussion of this draft should take place on the HTTPBIS working group
[1268]221    mailing list (, which is archived at
222    <eref target=""/>.
223  </t>
224  <t>
225    The current issues list is at
226    <eref target=""/> and related
227    documents (including fancy diffs) can be found at
[324]228    <eref target=""/>.
[36]229  </t>
[153]230  <t>
[1499]231    The changes in this draft are summarized in <xref target="changes.since.18"/>.
[153]232  </t>
236<section title="Introduction" anchor="introduction">
[163]238   This document defines HTTP/1.1 message payloads (a.k.a., content), the
[161]239   associated metadata header fields that define how the payload is intended
240   to be interpreted by a recipient, the request header fields that
[908]241   might influence content selection, and the various selection algorithms
[161]242   that are collectively referred to as HTTP content negotiation.
245   This document is currently disorganized in order to minimize the changes
246   between drafts and enable reviewers to see the smaller errata changes.
[980]247   A future draft will reorganize the sections to better reflect the content.
[161]248   In particular, the sections on entities will be renamed payload and moved
249   to the first half of the document, while the sections on content negotiation
250   and associated request header fields will be moved to the second half.  The
251   current mess reflects how widely dispersed these topics and associated
252   requirements had become in <xref target="RFC2616"/>.
[660]255<section title="Terminology" anchor="terminology">
257   This specification uses a number of terms to refer to the roles
258   played by participants in, and objects of, the HTTP communication.
261  <iref item="content negotiation"/>
262  <x:dfn>content negotiation</x:dfn>
263  <list>
264    <t>
265      The mechanism for selecting the appropriate representation when
[856]266      servicing a request. The representation in any response
[660]267      can be negotiated (including error responses).
268    </t>
269  </list>
[1452]273<section title="Conformance and Error Handling" anchor="intro.conformance.and.error.handling">
275   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
276   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
277   document are to be interpreted as described in <xref target="RFC2119"/>.
[1452]280   This document defines conformance criteria for several roles in HTTP
281   communication, including Senders, Recipients, Clients, Servers, User-Agents,
282   Origin Servers, Intermediaries, Proxies and Gateways. See &architecture;
283   for definitions of these terms.
286   An implementation is considered conformant if it complies with all of the
287   requirements associated with its role(s). Note that SHOULD-level requirements
288   are relevant here, unless one of the documented exceptions is applicable.
291   This document also uses ABNF to define valid protocol elements
292   (<xref target="notation"/>). In addition to the prose requirements placed
293   upon them, Senders &MUST-NOT; generate protocol elements that are invalid.
296   Unless noted otherwise, Recipients &MAY; take steps to recover a usable
297   protocol element from an invalid construct. However, HTTP does not define
298   specific error handling mechanisms, except in cases where it has direct
299   impact on security. This is because different uses of the protocol require
300   different error handling strategies; for example, a Web browser may wish to
301   transparently recover from a response where the Location header field
302   doesn't parse according to the ABNF, whereby in a systems control protocol
303   using HTTP, this type of error recovery could lead to dangerous consequences.
[424]307<section title="Syntax Notation" anchor="notation">
[425]308  <x:anchor-alias value="ALPHA"/>
309  <x:anchor-alias value="CR"/>
310  <x:anchor-alias value="DIGIT"/>
311  <x:anchor-alias value="LF"/>
312  <x:anchor-alias value="OCTET"/>
313  <x:anchor-alias value="VCHAR"/>
[1518]315   This specification uses the Augmented Backus-Naur Form (ABNF) notation
316   of <xref target="RFC5234"/> with the list rule extension defined in
317   &notation;.  <xref target="collected.abnf"/> shows the collected ABNF
318   with the list rule expanded.
[425]321  The following core rules are included by
322  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
323  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
324  DIGIT (decimal 0-9), DQUOTE (double quote),
325  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
[1425]326  OCTET (any 8-bit sequence of data), SP (space), and
327  VCHAR (any visible US-ASCII character).
330<section title="Core Rules" anchor="core.rules">
[229]331  <x:anchor-alias value="token"/>
[810]332  <x:anchor-alias value="word"/>
[357]333  <x:anchor-alias value="OWS"/>
[1396]335  The core rules below are defined in <xref target="Part1"/>:
337<figure><artwork type="abnf2616">
[1518]338  <x:ref>OWS</x:ref>            = &lt;OWS, defined in &whitespace;&gt;
339  <x:ref>token</x:ref>          = &lt;token, defined in &field-components;&gt;
340  <x:ref>word</x:ref>           = &lt;word, defined in &field-components;&gt;
344<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
[374]345  <x:anchor-alias value="absolute-URI"/>
[391]346  <x:anchor-alias value="partial-URI"/>
[457]347  <x:anchor-alias value="qvalue"/>
[206]349  The ABNF rules below are defined in other parts:
[207]351<figure><!--Part1--><artwork type="abnf2616">
[374]352  <x:ref>absolute-URI</x:ref>   = &lt;absolute-URI, defined in &uri;&gt;
[391]353  <x:ref>partial-URI</x:ref>    = &lt;partial-URI, defined in &uri;&gt;
[457]354  <x:ref>qvalue</x:ref>         = &lt;qvalue, defined in &qvalue;&gt;
[8]362<section title="Protocol Parameters" anchor="protocol.parameters">
[1176]364<section title="Character Encodings (charset)" anchor="character.sets">
[1176]366   HTTP uses charset names to indicate the character encoding of a
367   textual representation.
[229]369<t anchor="rule.charset">
370  <x:anchor-alias value="charset"/>
[1176]371   A character encoding is identified by a case-insensitive token. The
[8]372   complete set of tokens is defined by the IANA Character Set registry
[91]373   (<eref target=""/>).
375<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="charset"/>
[229]376  <x:ref>charset</x:ref> = <x:ref>token</x:ref>
379   Although HTTP allows an arbitrary token to be used as a charset
380   value, any token that has a predefined value within the IANA
[1176]381   Character Set registry &MUST; represent the character encoding defined
[8]382   by that registry. Applications &SHOULD; limit their use of character
[1176]383   encodings to those defined within the IANA registry.
[81]386   HTTP uses charset in two contexts: within an Accept-Charset request
[994]387   header field (in which the charset value is an unquoted token) and as the
388   value of a parameter in a Content-Type header field (within a request or
[81]389   response), in which case the parameter value of the charset parameter
[908]390   can be quoted.
[969]393   Implementors need to be aware of IETF character set requirements <xref target="RFC3629"/>
[8]394   <xref target="RFC2277"/>.
398<section title="Content Codings" anchor="content.codings">
[229]399  <x:anchor-alias value="content-coding"/>
401   Content coding values indicate an encoding transformation that has
[866]402   been or can be applied to a representation. Content codings are primarily
403   used to allow a representation to be compressed or otherwise usefully
[8]404   transformed without losing the identity of its underlying media type
[866]405   and without loss of information. Frequently, the representation is stored in
[8]406   coded form, transmitted directly, and only decoded by the recipient.
408<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="content-coding"/>
[229]409  <x:ref>content-coding</x:ref>   = <x:ref>token</x:ref>
412   All content-coding values are case-insensitive. HTTP/1.1 uses
413   content-coding values in the Accept-Encoding (<xref target="header.accept-encoding"/>) and
414   Content-Encoding (<xref target="header.content-encoding"/>) header fields. Although the value
415   describes the content-coding, what is more important is that it
416   indicates what decoding mechanism will be required to remove the
417   encoding.
[673]420   compress<iref item="compress (Coding Format)"/><iref item="Coding Format" subitem="compress"/>
421  <list>
422    <t>
423      See &compress-coding;.
424    </t>
425  </list>
[673]428   deflate<iref item="deflate (Coding Format)"/><iref item="Coding Format" subitem="deflate"/>
[8]429  <list>
430    <t>
[673]431      See &deflate-coding;.
[8]432    </t>
433  </list>
[673]436   gzip<iref item="gzip (Coding Format)"/><iref item="Coding Format" subitem="gzip"/>
437  <list>
438    <t>
439      See &gzip-coding;.
440    </t>
441  </list>
444<section title="Content Coding Registry" anchor="content.coding.registry">
[670]446   The HTTP Content Coding Registry defines the name space for the content
447   coding names.
450   Registrations &MUST; include the following fields:
451   <list style="symbols">
452     <t>Name</t>
453     <t>Description</t>
454     <t>Pointer to specification text</t>
455   </list>
[808]458   Names of content codings &MUST-NOT; overlap with names of transfer codings
[1514]459   (&transfer-codings;), unless the encoding transformation is identical (as
[808]460   is the case for the compression codings defined in
461   &compression-codings;).
[942]464   Values to be added to this name space require a specification
465   (see "Specification Required" in
[670]466   <xref target="RFC5226" x:fmt="of" x:sec="4.1"/>), and &MUST;
[8]467   conform to the purpose of content coding defined in this section.
470   The registry itself is maintained at
471   <eref target=""/>.
[8]477<section title="Media Types" anchor="media.types">
[229]478  <x:anchor-alias value="media-type"/>
479  <x:anchor-alias value="type"/>
480  <x:anchor-alias value="subtype"/>
[152]482   HTTP uses Internet Media Types <xref target="RFC2046"/> in the Content-Type (<xref target="header.content-type"/>)
[8]483   and Accept (<xref target="header.accept"/>) header fields in order to provide
484   open and extensible data typing and type negotiation.
486<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"/>
[357]487  <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> )
488  <x:ref>type</x:ref>       = <x:ref>token</x:ref>
489  <x:ref>subtype</x:ref>    = <x:ref>token</x:ref>
[229]491<t anchor="rule.parameter">
492  <x:anchor-alias value="attribute"/>
493  <x:anchor-alias value="parameter"/>
494  <x:anchor-alias value="value"/>
[1153]495   The type/subtype &MAY; be followed by parameters in the form of
496   attribute/value pairs.
[29]498<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"/>
[250]499  <x:ref>parameter</x:ref>      = <x:ref>attribute</x:ref> "=" <x:ref>value</x:ref>
500  <x:ref>attribute</x:ref>      = <x:ref>token</x:ref>
[810]501  <x:ref>value</x:ref>          = <x:ref>word</x:ref>
504   The type, subtype, and parameter attribute names are case-insensitive.
[370]505   Parameter values might or might not be case-sensitive, depending on the
506   semantics of the parameter name.  The presence or absence of a parameter might
[8]507   be significant to the processing of a media-type, depending on its
508   definition within the media type registry.
[908]511   A parameter value that matches the <x:ref>token</x:ref> production can be
[297]512   transmitted as either a token or within a quoted-string. The quoted and
513   unquoted values are equivalent.
[8]516   Note that some older HTTP applications do not recognize media type
517   parameters. When sending data to older HTTP applications,
518   implementations &SHOULD; only use media type parameters when they are
519   required by that type/subtype definition.
522   Media-type values are registered with the Internet Assigned Number
[91]523   Authority (IANA). The media type registration process is
[115]524   outlined in <xref target="RFC4288"/>. Use of non-registered media types is
[8]525   discouraged.
528<section title="Canonicalization and Text Defaults" anchor="canonicalization.and.text.defaults">
[874]530   Internet media types are registered with a canonical form. A
531   representation transferred via HTTP messages &MUST; be in the
[8]532   appropriate canonical form prior to its transmission except for
533   "text" types, as defined in the next paragraph.
536   When in canonical form, media subtypes of the "text" type use CRLF as
537   the text line break. HTTP relaxes this requirement and allows the
538   transport of text media with plain CR or LF alone representing a line
[874]539   break when it is done consistently for an entire representation. HTTP
540   applications &MUST; accept CRLF, bare CR, and bare LF as indicating
541   a line break in text media received via HTTP. In
542   addition, if the text is in a character encoding that does not
[8]543   use octets 13 and 10 for CR and LF respectively, as is the case for
[874]544   some multi-byte character encodings, HTTP allows the use of whatever octet
545   sequences are defined by that character encoding to represent the
[8]546   equivalent of CR and LF for line breaks. This flexibility regarding
[874]547   line breaks applies only to text media in the payload body; a bare CR
[8]548   or LF &MUST-NOT; be substituted for CRLF within any of the HTTP control
549   structures (such as header fields and multipart boundaries).
[874]552   If a representation is encoded with a content-coding, the underlying
[8]553   data &MUST; be in a form defined above prior to being encoded.
557<section title="Multipart Types" anchor="multipart.types">
[1101]559   MIME provides for a number of "multipart" types &mdash; encapsulations of
[1544]560   one or more representations within a single message body. All multipart
[97]561   types share a common syntax, as defined in <xref target="RFC2046" x:sec="5.1.1" x:fmt="of"/>,
562   and &MUST; include a boundary parameter as part of the media type
[8]563   value. The message body is itself a protocol element and &MUST;
564   therefore use only CRLF to represent line breaks between body-parts.
[1544]567   In general, HTTP treats a multipart message body no differently than
[852]568   any other media type: strictly as payload.  HTTP does not use the
[1544]569   multipart boundary as an indicator of message body length.
[97]570   <!-- jre: re-insert removed text pointing to caching? -->
[852]571   In all other respects, an HTTP user agent &SHOULD; follow the same or similar
[8]572   behavior as a MIME user agent would upon receipt of a multipart type.
[1544]573   The MIME header fields within each body-part of a multipart message body
[8]574   do not have any significance to HTTP beyond that defined by
575   their MIME semantics.
578   If an application receives an unrecognized multipart subtype, the
579   application &MUST; treat it as being equivalent to "multipart/mixed".
582  <t>
583    <x:h>Note:</x:h> The "multipart/form-data" type has been specifically defined
584    for carrying form data suitable for processing via the POST
585    request method, as described in <xref target="RFC2388"/>.
586  </t>
591<section title="Language Tags" anchor="language.tags">
[229]592  <x:anchor-alias value="language-tag"/>
[690]594   A language tag, as defined in <xref target="RFC5646"/>, identifies a
[613]595   natural language spoken, written, or otherwise conveyed by human beings for
596   communication of information to other human beings. Computer languages are
597   explicitly excluded. HTTP uses language tags within the Accept-Language and
598   Content-Language fields.
[613]601   In summary, a language tag is composed of one or more parts: A primary
602   language subtag followed by a possibly empty series of subtags:
[613]604<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="language-tag"/>
[690]605  <x:ref>language-tag</x:ref> = &lt;Language-Tag, defined in <xref target="RFC5646" x:sec="2.1"/>&gt;
608   White space is not allowed within the tag and all tags are case-insensitive.
[613]609   The name space of language subtags is administered by the IANA (see
610   <eref target=""/>).
613  <preamble>Example tags include:</preamble>
614<artwork type="example">
615  en, en-US, es-419, az-Arab, x-pig-latin, man-Nkoo-GN
[690]619   See <xref target="RFC5646"/> for further information.
[965]624<section title="Payload" anchor="payload">
[965]626   HTTP messages &MAY; transfer a payload if not otherwise restricted by
627   the request method or response status code.  The payload consists of
628   metadata, in the form of header fields, and data, in the form of the
[1544]629   sequence of octets in the message body after any transfer-coding has
[965]630   been decoded.
[965]632<iref item="payload"/>
634   A "<x:dfn>payload</x:dfn>" in HTTP is always a partial or complete
635   representation of some resource.  We use separate terms for payload
636   and representation because some messages contain only the associated
637   representation's header fields (e.g., responses to HEAD) or only some
638   part(s) of the representation (e.g., the 206 status code).
640<section title="Payload Header Fields" anchor="payload.header.fields">
641  <x:anchor-alias value="payload-header"/>
[965]643   HTTP header fields that specifically define the payload, rather than the
644   associated representation, are referred to as "payload header fields".
645   The following payload header fields are defined by HTTP/1.1:
[1138]647<texttable align="left">
648  <ttcol>Header Field Name</ttcol>
649  <ttcol>Defined in...</ttcol>
651  <c>Content-Length</c> <c>&header-content-length;</c>
652  <c>Content-Range</c> <c>&header-content-range;</c>
[874]656<section title="Payload Body" anchor="payload.body">
657  <x:anchor-alias value="payload-body"/>
[1544]659   A payload body is only present in a message when a message body is
[874]660   present, as described in &message-body;. The payload body is obtained
[1544]661   from the message body by decoding any Transfer-Encoding that might
[8]662   have been applied to ensure safe and proper transfer of the message.
[965]667<section title="Representation" anchor="representation">
668<iref item="representation"/>
[965]670   A "<x:dfn>representation</x:dfn>" is information in a format that can be readily
671   communicated from one party to another.  A resource representation
672   is information that reflects the state of that resource, as observed
673   at some point in the past (e.g., in a response to GET) or to be
674   desired at some point in the future (e.g., in a PUT request).
677   Most, but not all, representations transferred via HTTP are intended
678   to be a representation of the target resource (the resource identified
679   by the effective request URI).  The precise semantics of a representation
680   are determined by the type of message (request or response), the request
681   method, the response status code, and the representation metadata.
682   For example, the above semantic is true for the representation in any
683   200 (OK) response to GET and for the representation in any PUT request.
684   A 200 response to PUT, in contrast, contains either a representation
685   that describes the successful action or a representation of the target
686   resource, with the latter indicated by a Content-Location header field
687   with the same value as the effective request URI.  Likewise, response
688   messages with an error status code usually contain a representation that
689   describes the error and what next steps are suggested for resolving it.
692<section title="Representation Header Fields" anchor="representation.header.fields">
693  <x:anchor-alias value="representation-header"/>
695   Representation header fields define metadata about the representation data
[1544]696   enclosed in the message body or, if no message body is present, about
[965]697   the representation that would have been transferred in a 200 response
698   to a simultaneous GET request with the same effective request URI.
701   The following header fields are defined as representation metadata:
[1138]703<texttable align="left">
704  <ttcol>Header Field Name</ttcol>
705  <ttcol>Defined in...</ttcol>
707  <c>Content-Encoding</c> <c><xref target="header.content-encoding"/></c>
708  <c>Content-Language</c> <c><xref target="header.content-language"/></c>
709  <c>Content-Location</c> <c><xref target="header.content-location"/></c>
710  <c>Content-Type</c> <c><xref target="header.content-type"/></c>
711  <c>Expires</c> <c>&header-expires;</c>
712  <c>Last-Modified</c> <c>&header-last-modified;</c>
716<section title="Representation Data" anchor="">
717  <x:anchor-alias value="representation-data"/>
719   The representation body associated with an HTTP message is
720   either provided as the payload body of the message or
721   referred to by the message semantics and the effective request
722   URI.  The representation data is in a format and encoding defined by
723   the representation metadata header fields.
726   The data type of the representation data
727   is determined via the header fields Content-Type and Content-Encoding.
[8]728   These define a two-layer, ordered encoding model:
730<figure><artwork type="example">
[965]731  representation-data := Content-Encoding( Content-Type( bits ) )
[965]734   Content-Type specifies the media type of the underlying data, which
735   defines both the data format and how that data &SHOULD; be processed
736   by the recipient (within the scope of the request method semantics).
737   Any HTTP/1.1 message containing a payload body &SHOULD; include a
738   Content-Type header field defining the media type of the associated
739   representation unless that metadata is unknown to the sender.
[831]740   If the Content-Type header field is not present, it indicates that
[965]741   the sender does not know the media type of the representation;
742   recipients &MAY; either assume that the media type is
743   "application/octet-stream" (<xref target="RFC2046" x:fmt="," x:sec="4.5.1"/>)
[592]744   or examine the content to determine its type.
[965]747   In practice, resource owners do not always properly configure their origin
748   server to provide the correct Content-Type for a given representation,
749   with the result that some clients will examine a response body's content
750   and override the specified type.
[908]751   Clients that do so risk drawing incorrect conclusions, which might expose
[965]752   additional security risks (e.g., "privilege escalation").  Furthermore,
753   it is impossible to determine the sender's intent by examining the data
754   format: many data formats match multiple media types that differ only in
755   processing semantics.  Implementers are encouraged to provide a means of
756   disabling such "content sniffing" when it is used.
[908]759   Content-Encoding is used to indicate any additional content
[8]760   codings applied to the data, usually for the purpose of data
[965]761   compression, that are a property of the representation.  If
762   Content-Encoding is not present, then there is no additional
763   encoding beyond that defined by the Content-Type.
768<section title="Content Negotiation" anchor="content.negotiation">
[745]770   HTTP responses include a representation which contains information for
771   interpretation, whether by a human user or for further processing.
772   Often, the server has different ways of representing the
773   same information; for example, in different formats, languages,
774   or using different character encodings.
[745]777   HTTP clients and their users might have different or variable
778   capabilities, characteristics or preferences which would influence
779   which representation, among those available from the server,
780   would be best for the server to deliver. For this reason, HTTP
[1101]781   provides mechanisms for "content negotiation" &mdash; a process of
[745]782   allowing selection of a representation of a given resource,
783   when more than one is available.
[745]786   This specification defines two patterns of content negotiation;
787   "server-driven", where the server selects the representation based
788   upon the client's stated preferences, and "agent-driven" negotiation,
789   where the server provides a list of representations for the client to
790   choose from, based upon their metadata. In addition,  there are
791   other patterns: some applications use an "active content" pattern,
792   where the server returns active content which runs on the client
793   and, based on client available parameters, selects additional
794   resources to invoke. "Transparent Content Negotiation" (<xref target="RFC2295"/>)
795   has also been proposed.
798   These patterns are all widely used, and have trade-offs in applicability
799   and practicality. In particular, when the number of preferences or
800   capabilities to be expressed by a client are large (such as when many
801   different formats are supported by a user-agent), server-driven
[908]802   negotiation becomes unwieldy, and might not be appropriate. Conversely,
[745]803   when the number of representations to choose from is very large,
[908]804   agent-driven negotiation might not be appropriate.
807   Note that in all cases, the supplier of representations has the
808   responsibility for determining which representations might be
809   considered to be the "same information".
812<section title="Server-driven Negotiation" anchor="server-driven.negotiation">
814   If the selection of the best representation for a response is made by
815   an algorithm located at the server, it is called server-driven
816   negotiation. Selection is based on the available representations of
[763]817   the response (the dimensions over which it can vary; e.g., language,
[8]818   content-coding, etc.) and the contents of particular header fields in
819   the request message or on other information pertaining to the request
820   (such as the network address of the client).
823   Server-driven negotiation is advantageous when the algorithm for
824   selecting from among the available representations is difficult to
825   describe to the user agent, or when the server desires to send its
826   "best guess" to the client along with the first response (hoping to
827   avoid the round-trip delay of a subsequent request if the "best
828   guess" is good enough for the user). In order to improve the server's
829   guess, the user agent &MAY; include request header fields (Accept,
830   Accept-Language, Accept-Encoding, etc.) which describe its
831   preferences for such a response.
834   Server-driven negotiation has disadvantages:
835  <list style="numbers">
836    <t>
837         It is impossible for the server to accurately determine what
838         might be "best" for any given user, since that would require
839         complete knowledge of both the capabilities of the user agent
840         and the intended use for the response (e.g., does the user want
841         to view it on screen or print it on paper?).
842    </t>
843    <t>
844         Having the user agent describe its capabilities in every
845         request can be both very inefficient (given that only a small
846         percentage of responses have multiple representations) and a
847         potential violation of the user's privacy.
848    </t>
849    <t>
850         It complicates the implementation of an origin server and the
851         algorithms for generating responses to a request.
852    </t>
853    <t>
[908]854         It might limit a public cache's ability to use the same response
[8]855         for multiple user's requests.
856    </t>
857  </list>
[1335]860   Server-driven negotiation allows the user agent to specify its preferences,
[1514]861   but it cannot expect responses to always honor them. For example, the origin
[1335]862   server might not implement server-driven negotiation, or it might decide that
863   sending a response that doesn't conform to them is better than sending a 406
864   (Not Acceptable) response.
867   Many of the mechanisms for expressing preferences use quality values to
868   declare relative preference. See &qvalue; for more information.
[1163]871   HTTP/1.1 includes the following header fields for enabling
[8]872   server-driven negotiation through description of user agent
873   capabilities and user preferences: Accept (<xref target="header.accept"/>), Accept-Charset
874   (<xref target="header.accept-charset"/>), Accept-Encoding (<xref target="header.accept-encoding"/>), Accept-Language
[745]875   (<xref target="header.accept-language"/>), and User-Agent (&header-user-agent;).
876   However, an origin server is not limited to these dimensions and &MAY; vary
[1163]877   the response based on any aspect of the request, including aspects
878   of the connection (e.g., IP address) or information within extension
879   header fields not defined by this specification.
882  <t>
883    <x:h>Note:</x:h> In practice, User-Agent based negotiation is fragile,
884    because new clients might not be recognized.
885  </t>
[115]888   The Vary header field (&header-vary;) can be used to express the parameters the
[8]889   server uses to select a representation that is subject to server-driven
[29]890   negotiation.
894<section title="Agent-driven Negotiation" anchor="agent-driven.negotiation">
896   With agent-driven negotiation, selection of the best representation
897   for a response is performed by the user agent after receiving an
898   initial response from the origin server. Selection is based on a list
899   of the available representations of the response included within the
[874]900   header fields or body of the initial response, with each
[8]901   representation identified by its own URI. Selection from among the
[908]902   representations can be performed automatically (if the user agent is
[8]903   capable of doing so) or manually by the user selecting from a
904   generated (possibly hypertext) menu.
907   Agent-driven negotiation is advantageous when the response would vary
908   over commonly-used dimensions (such as type, language, or encoding),
909   when the origin server is unable to determine a user agent's
910   capabilities from examining the request, and generally when public
911   caches are used to distribute server load and reduce network usage.
914   Agent-driven negotiation suffers from the disadvantage of needing a
915   second request to obtain the best alternate representation. This
916   second request is only efficient when caching is used. In addition,
917   this specification does not define any mechanism for supporting
918   automatic selection, though it also does not prevent any such
919   mechanism from being developed as an extension and used within
920   HTTP/1.1.
[745]923   This specification defines the 300 (Multiple Choices) and 406 (Not Acceptable)
[8]924   status codes for enabling agent-driven negotiation when the server is
925   unwilling or unable to provide a varying response using server-driven
926   negotiation.
[1415]931<section title="Header Field Definitions" anchor="header.field.definitions">
[117]933   This section defines the syntax and semantics of HTTP/1.1 header fields
934   related to the payload of messages.
[8]937<section title="Accept" anchor="header.accept">
[1120]938  <iref primary="true" item="Accept header field" x:for-anchor=""/>
939  <iref primary="true" item="Header Fields" subitem="Accept" x:for-anchor=""/>
[229]940  <x:anchor-alias value="Accept"/>
[370]941  <x:anchor-alias value="accept-ext"/>
[229]942  <x:anchor-alias value="accept-params"/>
943  <x:anchor-alias value="media-range"/>
[1163]945   The "Accept" header field can be used by user agents to specify
[994]946   response media types that are acceptable. Accept header fields can be used to
[698]947   indicate that the request is specifically limited to a small set of desired
948   types, as in the case of a request for an in-line image.
[1234]950<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"/>
951  <x:ref>Accept</x:ref> = #( <x:ref>media-range</x:ref> [ <x:ref>accept-params</x:ref> ] )
[229]953  <x:ref>media-range</x:ref>    = ( "*/*"
[334]954                   / ( <x:ref>type</x:ref> "/" "*" )
955                   / ( <x:ref>type</x:ref> "/" <x:ref>subtype</x:ref> )
[370]956                   ) *( <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> <x:ref>parameter</x:ref> )
957  <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> )
[1039]958  <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> ]
961   The asterisk "*" character is used to group media types into ranges,
962   with "*/*" indicating all media types and "type/*" indicating all
963   subtypes of that type. The media-range &MAY; include media type
964   parameters that are applicable to that range.
967   Each media-range &MAY; be followed by one or more accept-params,
968   beginning with the "q" parameter for indicating a relative quality
969   factor. The first "q" parameter (if any) separates the media-range
970   parameter(s) from the accept-params. Quality factors allow the user
971   or user agent to indicate the relative degree of preference for that
[457]972   media-range, using the qvalue scale from 0 to 1 (&qvalue;). The
[8]973   default value is q=1.
976  <t>
977    <x:h>Note:</x:h> Use of the "q" parameter name to separate media type
978    parameters from Accept extension parameters is due to historical
979    practice. Although this prevents any media type parameter named
980    "q" from being used with a media range, such an event is believed
981    to be unlikely given the lack of any "q" parameters in the IANA
982    media type registry and the rare usage of any media type
983    parameters in Accept. Future media types are discouraged from
984    registering any parameter named "q".
985  </t>
988   The example
990<figure><artwork type="example">
[357]991  Accept: audio/*; q=0.2, audio/basic
994   &SHOULD; be interpreted as "I prefer audio/basic, but send me any audio
[879]995   type if it is the best available after an 80% mark-down in quality".
[1406]998   A request without any Accept header field implies that the user agent
999   will accept any media type in response.
1000   If an Accept header field is present in a request and none of the
1001   available representations for the response have a media type that is
1002   listed as acceptable, the origin server &MAY; either
1003   honor the Accept header field by sending a 406 (Not Acceptable) response
1004   or disregard the Accept header field by treating the response as if
1005   it is not subject to content negotiation.
1008   A more elaborate example is
1010<figure><artwork type="example">
[357]1011  Accept: text/plain; q=0.5, text/html,
1012          text/x-dvi; q=0.8, text/x-c
1015   Verbally, this would be interpreted as "text/html and text/x-c are
1016   the preferred media types, but if they do not exist, then send the
[866]1017   text/x-dvi representation, and if that does not exist, send the text/plain
[879]1018   representation".
1021   Media ranges can be overridden by more specific media ranges or
1022   specific media types. If more than one media range applies to a given
1023   type, the most specific reference has precedence. For example,
1025<figure><artwork type="example">
[1244]1026  Accept: text/*, text/plain, text/plain;format=flowed, */*
1029   have the following precedence:
[459]1030   <list style="numbers">
[1244]1031    <t>text/plain;format=flowed</t>
1032    <t>text/plain</t>
[459]1033    <t>text/*</t>
1034    <t>*/*</t>
1035   </list>
1038   The media type quality factor associated with a given type is
1039   determined by finding the media range with the highest precedence
1040   which matches that type. For example,
1042<figure><artwork type="example">
[357]1043  Accept: text/*;q=0.3, text/html;q=0.7, text/html;level=1,
1044          text/html;level=2;q=0.4, */*;q=0.5
1047   would cause the following values to be associated:
[459]1049<texttable align="left">
1050  <ttcol>Media Type</ttcol><ttcol>Quality Value</ttcol>
1051  <c>text/html;level=1</c>    <c>1</c>
1052  <c>text/html</c>            <c>0.7</c>
1053  <c>text/plain</c>           <c>0.3</c>
1054  <c>image/jpeg</c>           <c>0.5</c>
1055  <c>text/html;level=2</c>    <c>0.4</c>
1056  <c>text/html;level=3</c>    <c>0.7</c>
1059      <x:h>Note:</x:h> A user agent might be provided with a default set of quality
1060      values for certain media ranges. However, unless the user agent is
1061      a closed system which cannot interact with other rendering agents,
1062      this default set ought to be configurable by the user.
1066<section title="Accept-Charset" anchor="header.accept-charset">
[1120]1067  <iref primary="true" item="Accept-Charset header field" x:for-anchor=""/>
1068  <iref primary="true" item="Header Fields" subitem="Accept-Charset" x:for-anchor=""/>
[229]1069  <x:anchor-alias value="Accept-Charset"/>
[1163]1071   The "Accept-Charset" header field can be used by user agents to
[1176]1072   indicate what character encodings are acceptable in a response
1073   payload. This field allows
[8]1074   clients capable of understanding more comprehensive or special-purpose
[1176]1075   character encodings to signal that capability to a server which is capable of
1076   representing documents in those character encodings.
[1234]1078<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Charset"/>
1079  <x:ref>Accept-Charset</x:ref> = 1#( ( <x:ref>charset</x:ref> / "*" )
[376]1080                         [ <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> ] )
[1176]1083   Character encoding values (a.k.a., charsets) are described in
1084   <xref target="character.sets"/>. Each charset &MAY; be given an
1085   associated quality value which represents the user's preference
1086   for that charset. The default value is q=1. An example is
1088<figure><artwork type="example">
[357]1089  Accept-Charset: iso-8859-5, unicode-1-1;q=0.8
1092   The special value "*", if present in the Accept-Charset field,
[1240]1093   matches every character encoding which is not mentioned elsewhere in the
1094   Accept-Charset field. If no "*" is present in an Accept-Charset field, then
1095   all character encodings not explicitly mentioned get a quality value of 0.
[1406]1098   A request without any Accept-Charset header field implies that the user
1099   agent will accept any character encoding in response.
1100   If an Accept-Charset header field is present in a request and none of the
1101   available representations for the response have a character encoding that
1102   is listed as acceptable, the origin server &MAY; either honor the
1103   Accept-Charset header field by sending a 406 (Not Acceptable) response or
1104   disregard the Accept-Charset header field by treating the response as if
1105   it is not subject to content negotiation.
1109<section title="Accept-Encoding" anchor="header.accept-encoding">
[1120]1110  <iref primary="true" item="Accept-Encoding header field" x:for-anchor=""/>
1111  <iref primary="true" item="Header Fields" subitem="Accept-Encoding" x:for-anchor=""/>
[229]1112  <x:anchor-alias value="Accept-Encoding"/>
1113  <x:anchor-alias value="codings"/>
[1163]1115   The "Accept-Encoding" header field can be used by user agents to
[698]1116   indicate what response content-codings (<xref target="content.codings"/>)
[1406]1117   are acceptable in the response.  An "identity" token is used as a synonym
1118   for "no encoding" in order to communicate when no encoding is preferred.
[1234]1120<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Encoding"/><iref primary="true" item="Grammar" subitem="codings"/>
1121  <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> ] )
[1423]1122  <x:ref>codings</x:ref>          = <x:ref>content-coding</x:ref> / "identity" / "*"
[248]1125   Each codings value &MAY; be given an associated quality value which
1126   represents the preference for that encoding. The default value is q=1.
[1406]1129   For example,
1131<figure><artwork type="example">
[357]1132  Accept-Encoding: compress, gzip
1133  Accept-Encoding:
1134  Accept-Encoding: *
1135  Accept-Encoding: compress;q=0.5, gzip;q=1.0
1136  Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0
[1406]1139   A server tests whether a content-coding for a given representation is
1140   acceptable, according to an Accept-Encoding field, using these rules:
[8]1141  <list style="numbers">
1142      <t>The special "*" symbol in an Accept-Encoding field matches any
1143         available content-coding not explicitly listed in the header
1144         field.</t>
[1406]1146      <t>If the representation has no content-coding, then it is acceptable
1147         by default unless specifically excluded by the Accept-Encoding field
1148         stating either "identity;q=0" or "*;q=0" without a more specific
1149         entry for "identity".</t>
1151      <t>If the representation's content-coding is one of the content-codings
1152         listed in the Accept-Encoding field, then it is acceptable unless
1153         it is accompanied by a qvalue of 0. (As defined in &qvalue;, a
1154         qvalue of 0 means "not acceptable".)</t>
[8]1156      <t>If multiple content-codings are acceptable, then the acceptable
1157         content-coding with the highest non-zero qvalue is preferred.</t>
1158  </list>
[1406]1161   An Accept-Encoding header field with a combined field-value that is empty
1162   implies that the user agent does not want any content-coding in response.
1163   If an Accept-Encoding header field is present in a request and none of the
1164   available representations for the response have a content-coding that
1165   is listed as acceptable, the origin server &SHOULD; send a response
1166   without any content-coding.
[1406]1169   A request without an Accept-Encoding header field implies that the user
1170   agent will accept any content-coding in response, but a representation
1171   without content-coding is preferred for compatibility with the widest
1172   variety of user agents.
1175  <t>
1176    <x:h>Note:</x:h> Most HTTP/1.0 applications do not recognize or obey qvalues
1177    associated with content-codings. This means that qvalues will not
1178    work and are not permitted with x-gzip or x-compress.
1179  </t>
1183<section title="Accept-Language" anchor="header.accept-language">
[1120]1184  <iref primary="true" item="Accept-Language header field" x:for-anchor=""/>
1185  <iref primary="true" item="Header Fields" subitem="Accept-Language" x:for-anchor=""/>
[229]1186  <x:anchor-alias value="Accept-Language"/>
1187  <x:anchor-alias value="language-range"/>
[1163]1189   The "Accept-Language" header field can be used by user agents to
[698]1190   indicate the set of natural languages that are preferred in the response.
1191   Language tags are defined in <xref target="language.tags"/>.
[1234]1193<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Language"/><iref primary="true" item="Grammar" subitem="language-range"/>
1194  <x:ref>Accept-Language</x:ref> =
[370]1195                    1#( <x:ref>language-range</x:ref> [ <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> ] )
[1234]1196  <x:ref>language-range</x:ref>  =
[303]1197            &lt;language-range, defined in <xref target="RFC4647" x:fmt="," x:sec="2.1"/>&gt;
[303]1200   Each language-range can be given an associated quality value which
[8]1201   represents an estimate of the user's preference for the languages
1202   specified by that range. The quality value defaults to "q=1". For
1203   example,
1205<figure><artwork type="example">
[357]1206  Accept-Language: da, en-gb;q=0.8, en;q=0.7
1209   would mean: "I prefer Danish, but will accept British English and
[879]1210   other types of English".
[724]1211   (see also <xref target="RFC4647" x:sec="2.3" x:fmt="of"/>)
[724]1214   For matching, <xref target="RFC4647" x:sec="3" x:fmt="of"/> defines
1215   several matching schemes. Implementations can offer the most appropriate
1216   matching scheme for their requirements.
1219  <t>
[756]1220    <x:h>Note:</x:h> The "Basic Filtering" scheme (<xref target="RFC4647"
[724]1221    x:fmt="," x:sec="3.3.1"/>) is identical to the matching scheme that was
1222    previously defined in <xref target="RFC2616" x:fmt="of" x:sec="14.4"/>.
[563]1223  </t>
1226   It might be contrary to the privacy expectations of the user to send
[994]1227   an Accept-Language header field with the complete linguistic preferences of
[8]1228   the user in every request. For a discussion of this issue, see
[994]1229   <xref target=""/>.
1232   As intelligibility is highly dependent on the individual user, it is
1233   recommended that client applications make the choice of linguistic
1234   preference available to the user. If the choice is not made
1235   available, then the Accept-Language header field &MUST-NOT; be given in
1236   the request.
1239  <t>
1240    <x:h>Note:</x:h> When making the choice of linguistic preference available to
1241    the user, we remind implementors of  the fact that users are not
1242    familiar with the details of language matching as described above,
[969]1243    and ought to be provided appropriate guidance. As an example, users
[563]1244    might assume that on selecting "en-gb", they will be served any
1245    kind of English document if British English is not available. A
1246    user agent might suggest in such a case to add "en" to get the
1247    best matching behavior.
1248  </t>
1252<section title="Content-Encoding" anchor="header.content-encoding">
[1120]1253  <iref primary="true" item="Content-Encoding header field" x:for-anchor=""/>
1254  <iref primary="true" item="Header Fields" subitem="Content-Encoding" x:for-anchor=""/>
[229]1255  <x:anchor-alias value="Content-Encoding"/>
[965]1257   The "Content-Encoding" header field indicates what content-codings
[1406]1258   have been applied to the representation beyond those inherent in the media
1259   type, and thus what decoding mechanisms must be applied in order to obtain
1260   the media-type referenced by the Content-Type header field.
1261   Content-Encoding is primarily used to allow a representation to be
1262   compressed without losing the identity of its underlying media type.
[1234]1264<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Encoding"/>
1265  <x:ref>Content-Encoding</x:ref> = 1#<x:ref>content-coding</x:ref>
1268   Content codings are defined in <xref target="content.codings"/>. An example of its use is
1270<figure><artwork type="example">
[357]1271  Content-Encoding: gzip
[866]1274   The content-coding is a characteristic of the representation.
1275   Typically, the representation body is stored with this
[8]1276   encoding and is only decoded before rendering or analogous usage.
[1107]1277   However, a transforming proxy &MAY; modify the content-coding if the
[8]1278   new coding is known to be acceptable to the recipient, unless the
1279   "no-transform" cache-control directive is present in the message.
[1406]1282   If the media type includes an inherent encoding, such as a data format
1283   that is always compressed, then that encoding would not be restated as
1284   a Content-Encoding even if it happens to be the same algorithm as one
1285   of the content-codings.  Such a content-coding would only be listed if,
1286   for some bizarre reason, it is applied a second time to form the
1287   representation.  Likewise, an origin server might choose to publish the
1288   same payload data as multiple representations that differ only in whether
1289   the coding is defined as part of Content-Type or Content-Encoding, since
1290   some user agents will behave differently in their handling of each
1291   response (e.g., open a "Save as ..." dialog instead of automatic
1292   decompression and rendering of content).
[1406]1295   A representation that has a content-coding applied to it &MUST; include
1296   a Content-Encoding header field (<xref target="header.content-encoding"/>)
1297   that lists the content-coding(s) applied.
[866]1300   If multiple encodings have been applied to a representation, the content
[8]1301   codings &MUST; be listed in the order in which they were applied.
1302   Additional information about the encoding parameters &MAY; be provided
[866]1303   by other header fields not defined by this specification.
1306   If the content-coding of a representation in a request message is not
1307   acceptable to the origin server, the server &SHOULD; respond with a
1308   status code of 415 (Unsupported Media Type).
1312<section title="Content-Language" anchor="header.content-language">
[1120]1313  <iref primary="true" item="Content-Language header field" x:for-anchor=""/>
1314  <iref primary="true" item="Header Fields" subitem="Content-Language" x:for-anchor=""/>
[229]1315  <x:anchor-alias value="Content-Language"/>
[965]1317   The "Content-Language" header field describes the natural
[866]1318   language(s) of the intended audience for the representation. Note that this might
[874]1319   not be equivalent to all the languages used within the representation.
[1234]1321<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Language"/>
1322  <x:ref>Content-Language</x:ref> = 1#<x:ref>language-tag</x:ref>
1325   Language tags are defined in <xref target="language.tags"/>. The primary purpose of
1326   Content-Language is to allow a user to identify and differentiate
[866]1327   representations according to the user's own preferred language. Thus, if the
[8]1328   body content is intended only for a Danish-literate audience, the
1329   appropriate field is
1331<figure><artwork type="example">
[357]1332  Content-Language: da
1335   If no Content-Language is specified, the default is that the content
1336   is intended for all language audiences. This might mean that the
1337   sender does not consider it to be specific to any natural language,
1338   or that the sender does not know for which language it is intended.
1341   Multiple languages &MAY; be listed for content that is intended for
1342   multiple audiences. For example, a rendition of the "Treaty of
[879]1343   Waitangi", presented simultaneously in the original Maori and English
[8]1344   versions, would call for
1346<figure><artwork type="example">
[357]1347  Content-Language: mi, en
[866]1350   However, just because multiple languages are present within a representation
[8]1351   does not mean that it is intended for multiple linguistic audiences.
1352   An example would be a beginner's language primer, such as "A First
[879]1353   Lesson in Latin", which is clearly intended to be used by an
[8]1354   English-literate audience. In this case, the Content-Language would
1355   properly only include "en".
[1101]1358   Content-Language &MAY; be applied to any media type &mdash; it is not
[8]1359   limited to textual documents.
1363<section title="Content-Location" anchor="header.content-location">
[1120]1364  <iref primary="true" item="Content-Location header field" x:for-anchor=""/>
1365  <iref primary="true" item="Header Fields" subitem="Content-Location" x:for-anchor=""/>
[229]1366  <x:anchor-alias value="Content-Location"/>
[856]1368   The "Content-Location" header field supplies a URI that can be used
1369   as a specific identifier for the representation in this message.
1370   In other words, if one were to perform a GET on this URI at the time
1371   of this message's generation, then a 200 response would contain the
1372   same representation that is enclosed as payload in this message.
[1234]1374<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Location"/>
1375  <x:ref>Content-Location</x:ref> = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
[972]1378   The Content-Location value is not a replacement for the effective
[856]1379   Request URI (&effective-request-uri;).  It is representation metadata.
1380   It has the same syntax and semantics as the header field of the same name
[858]1381   defined for MIME body parts in <xref target="RFC2557" x:fmt="of" x:sec="4"/>.
[856]1382   However, its appearance in an HTTP message has some special implications
1383   for HTTP recipients.
[856]1386   If Content-Location is included in a response message and its value
[965]1387   is the same as the effective request URI, then the response payload
[856]1388   &SHOULD; be considered the current representation of that resource.
1389   For a GET or HEAD request, this is the same as the default semantics
1390   when no Content-Location is provided by the server.  For a state-changing
[1161]1391   request like PUT or POST, it implies that the server's response contains
[856]1392   the new representation of that resource, thereby distinguishing it from
1393   representations that might only report about the action (e.g., "It worked!").
1394   This allows authoring applications to update their local copies without
1395   the need for a subsequent GET request.
[856]1398   If Content-Location is included in a response message and its value
[965]1399   differs from the effective request URI, then the origin server is
[856]1400   informing recipients that this representation has its own, presumably
1401   more specific, identifier.  For a GET or HEAD request, this is an
[965]1402   indication that the effective request URI identifies a resource that
[856]1403   is subject to content negotiation and the representation selected for
1404   this response can also be found at the identified URI.  For other
1405   methods, such a Content-Location indicates that this representation
1406   contains a report on the action's status and the same report is
1407   available (for future access with GET) at the given URI.  For
[1161]1408   example, a purchase transaction made via a POST request might
[856]1409   include a receipt document as the payload of the 200 response;
1410   the Content-Location value provides an identifier for retrieving
1411   a copy of that same receipt in the future.
1414   If Content-Location is included in a request message, then it &MAY;
1415   be interpreted by the origin server as an indication of where the
1416   user agent originally obtained the content of the enclosed
1417   representation (prior to any subsequent modification of the content
1418   by that user agent).  In other words, the user agent is providing
1419   the same representation metadata that it received with the original
1420   representation.  However, such interpretation &MUST-NOT; be used to
1421   alter the semantics of the method requested by the client.  For
1422   example, if a client makes a PUT request on a negotiated resource
1423   and the origin server accepts that PUT (without redirection), then the
1424   new set of values for that resource is expected to be consistent with
1425   the one representation supplied in that PUT; the Content-Location
1426   cannot be used as a form of reverse content selection that
1427   identifies only one of the negotiated representations to be updated.
1428   If the user agent had wanted the latter semantics, it would have applied
1429   the PUT directly to the Content-Location URI.
1432   A Content-Location field received in a request message is transitory
1433   information that &SHOULD-NOT; be saved with other representation
1434   metadata for use in later responses.  The Content-Location's value
1435   might be saved for use in other contexts, such as within source links
1436   or other metadata.
1439   A cache cannot assume that a representation with a Content-Location
[8]1440   different from the URI used to retrieve it can be used to respond to
[856]1441   later requests on that Content-Location URI.
[965]1444   If the Content-Location value is a partial URI, the partial URI is
1445   interpreted relative to the effective request URI.
1449<section title="Content-Type" anchor="header.content-type">
[1120]1450  <iref primary="true" item="Content-Type header field" x:for-anchor=""/>
1451  <iref primary="true" item="Header Fields" subitem="Content-Type" x:for-anchor=""/>
[229]1452  <x:anchor-alias value="Content-Type"/>
[965]1454   The "Content-Type" header field indicates the media type of the
[874]1455   representation. In the case of responses to the HEAD method, the media type is
[698]1456   that which would have been sent had the request been a GET.
[1234]1458<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Type"/>
1459  <x:ref>Content-Type</x:ref> = <x:ref>media-type</x:ref>
1462   Media types are defined in <xref target="media.types"/>. An example of the field is
1464<figure><artwork type="example">
[357]1465  Content-Type: text/html; charset=ISO-8859-4
[965]1468   Further discussion of Content-Type is provided in <xref target=""/>.
[29]1474<section title="IANA Considerations" anchor="IANA.considerations">
[921]1475<section title="Header Field Registration" anchor="header.field.registration">
[969]1477   The Message Header Field Registry located at <eref target=""/> shall be updated
[290]1478   with the permanent registrations below (see <xref target="RFC3864"/>):
[680]1480<?BEGININC p3-payload.iana-headers ?>
[253]1481<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
[290]1482<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
[253]1483   <ttcol>Header Field Name</ttcol>
1484   <ttcol>Protocol</ttcol>
1485   <ttcol>Status</ttcol>
1486   <ttcol>Reference</ttcol>
1488   <c>Accept</c>
1489   <c>http</c>
1490   <c>standard</c>
1491   <c>
1492      <xref target="header.accept"/>
1493   </c>
1494   <c>Accept-Charset</c>
1495   <c>http</c>
1496   <c>standard</c>
1497   <c>
1498      <xref target="header.accept-charset"/>
1499   </c>
1500   <c>Accept-Encoding</c>
1501   <c>http</c>
1502   <c>standard</c>
1503   <c>
1504      <xref target="header.accept-encoding"/>
1505   </c>
1506   <c>Accept-Language</c>
1507   <c>http</c>
1508   <c>standard</c>
1509   <c>
1510      <xref target="header.accept-language"/>
1511   </c>
1512   <c>Content-Encoding</c>
1513   <c>http</c>
1514   <c>standard</c>
1515   <c>
1516      <xref target="header.content-encoding"/>
1517   </c>
1518   <c>Content-Language</c>
1519   <c>http</c>
1520   <c>standard</c>
1521   <c>
1522      <xref target="header.content-language"/>
1523   </c>
1524   <c>Content-Location</c>
1525   <c>http</c>
1526   <c>standard</c>
1527   <c>
1528      <xref target="header.content-location"/>
1529   </c>
1530   <c>Content-Type</c>
1531   <c>http</c>
1532   <c>standard</c>
1533   <c>
1534      <xref target="header.content-type"/>
1535   </c>
[291]1536   <c>MIME-Version</c>
1537   <c>http</c>
[937]1538   <c>standard</c>
[291]1539   <c>
1540      <xref target="mime-version"/>
1541   </c>
[680]1544<?ENDINC p3-payload.iana-headers ?>
[290]1546   The change controller is: "IETF ( - Internet Engineering Task Force".
[668]1550<section title="Content Coding Registry" anchor="content.coding.registration">
1552   The registration procedure for HTTP Content Codings is now defined
[670]1553   by <xref target="content.coding.registry"/> of this document.
1556   The HTTP Content Codings Registry located at <eref target=""/>
[969]1557   shall be updated with the registration below:
1559<texttable align="left" suppress-title="true" anchor="iana.content.coding.registration.table">
[670]1560   <ttcol>Name</ttcol>
[668]1561   <ttcol>Description</ttcol>
1562   <ttcol>Reference</ttcol>
1563   <c>compress</c>
1564   <c>UNIX "compress" program method</c>
1565   <c>
[673]1566      &compress-coding;
[668]1567   </c>
1568   <c>deflate</c>
[806]1569   <c>"deflate" compression mechanism (<xref target="RFC1951"/>) used inside
1570   the "zlib" data format (<xref target="RFC1950"/>)
1571   </c>
[668]1572   <c>
[673]1573      &deflate-coding;
[668]1574   </c>
1575   <c>gzip</c>
1576   <c>Same as GNU zip <xref target="RFC1952"/></c>
1577   <c>
[673]1578      &gzip-coding;
[668]1579   </c>
[1423]1580   <c>identity</c>
1581   <c>reserved (synonym for "no encoding" in Accept-Encoding header field)</c>
1582   <c>
1583      <xref target="header.accept-encoding"/>
1584   </c>
[8]1590<section title="Security Considerations" anchor="security.considerations">
1592   This section is meant to inform application developers, information
1593   providers, and users of the security limitations in HTTP/1.1 as
1594   described by this document. The discussion does not include
1595   definitive solutions to the problems revealed, though it does make
1596   some suggestions for reducing security risks.
[994]1599<section title="Privacy Issues Connected to Accept Header Fields" anchor="">
[1514]1601   Accept header fields can reveal information about the user to all
[994]1602   servers which are accessed. The Accept-Language header field in particular
[8]1603   can reveal information the user would consider to be of a private
1604   nature, because the understanding of particular languages is often
1605   strongly correlated to the membership of a particular ethnic group.
1606   User agents which offer the option to configure the contents of an
[994]1607   Accept-Language header field to be sent in every request are strongly
[8]1608   encouraged to let the configuration process include a message which
1609   makes the user aware of the loss of privacy involved.
1612   An approach that limits the loss of privacy would be for a user agent
[994]1613   to omit the sending of Accept-Language header fields by default, and to ask
1614   the user whether or not to start sending Accept-Language header fields to a
[1163]1615   server if it detects, by looking for any Vary header fields
[8]1616   generated by the server, that such sending could improve the quality
1617   of service.
1620   Elaborate user-customized accept header fields sent in every request,
1621   in particular if these include quality values, can be used by servers
1622   as relatively reliable and long-lived user identifiers. Such user
1623   identifiers would allow content providers to do click-trail tracking,
1624   and would allow collaborating content providers to match cross-server
1625   click-trails or form submissions of individual users. Note that for
1626   many users not behind a proxy, the network address of the host
1627   running the user agent will also serve as a long-lived user
1628   identifier. In environments where proxies are used to enhance
1629   privacy, user agents ought to be conservative in offering accept
1630   header configuration options to end users. As an extreme privacy
[994]1631   measure, proxies could filter the accept header fields in relayed requests.
[8]1632   General purpose user agents which provide a high degree of header
1633   configurability &SHOULD; warn users about the loss of privacy which can
1634   be involved.
[1364]1640<section title="Acknowledgments" anchor="acks">
1642  See &acks;.
[119]1648<references title="Normative References">
[31]1650<reference anchor="Part1">
[119]1651  <front>
1652    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
1653    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
[1106]1654      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1655      <address><email></email></address>
1656    </author>
1657    <author initials="J." surname="Gettys" fullname="Jim Gettys">
[844]1658      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1659      <address><email></email></address>
[119]1660    </author>
1661    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1662      <organization abbrev="HP">Hewlett-Packard Company</organization>
1663      <address><email></email></address>
1664    </author>
1665    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1666      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1667      <address><email></email></address>
1668    </author>
1669    <author initials="L." surname="Masinter" fullname="Larry Masinter">
[1106]1670      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1671      <address><email></email></address>
1672    </author>
1673    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1674      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1675      <address><email></email></address>
1676    </author>
1677    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1678      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1679      <address><email></email></address>
1680    </author>
1681    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1682      <organization abbrev="W3C">World Wide Web Consortium</organization>
1683      <address><email></email></address>
1684    </author>
1685    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1686      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1687      <address><email></email></address>
1688    </author>
1689    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1690  </front>
1691  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
1692  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
1695<reference anchor="Part2">
[119]1696  <front>
1697    <title abbrev="HTTP/1.1">HTTP/1.1, part 2: Message Semantics</title>
1698    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
[1106]1699      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1700      <address><email></email></address>
1701    </author>
1702    <author initials="J." surname="Gettys" fullname="Jim Gettys">
[844]1703      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1704      <address><email></email></address>
[119]1705    </author>
1706    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1707      <organization abbrev="HP">Hewlett-Packard Company</organization>
1708      <address><email></email></address>
1709    </author>
1710    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1711      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1712      <address><email></email></address>
1713    </author>
1714    <author initials="L." surname="Masinter" fullname="Larry Masinter">
[1106]1715      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1716      <address><email></email></address>
1717    </author>
1718    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1719      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1720      <address><email></email></address>
1721    </author>
1722    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1723      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1724      <address><email></email></address>
1725    </author>
1726    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1727      <organization abbrev="W3C">World Wide Web Consortium</organization>
1728      <address><email></email></address>
1729    </author>
1730    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1731      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1732      <address><email></email></address>
1733    </author>
1734    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1735  </front>
1736  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"/>
1737  <x:source href="p2-semantics.xml" basename="p2-semantics"/>
1740<reference anchor="Part4">
[119]1741  <front>
1742    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
1743    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
[1106]1744      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1745      <address><email></email></address>
1746    </author>
1747    <author initials="J." surname="Gettys" fullname="Jim Gettys">
[844]1748      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1749      <address><email></email></address>
[119]1750    </author>
1751    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1752      <organization abbrev="HP">Hewlett-Packard Company</organization>
1753      <address><email></email></address>
1754    </author>
1755    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1756      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1757      <address><email></email></address>
1758    </author>
1759    <author initials="L." surname="Masinter" fullname="Larry Masinter">
[1106]1760      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1761      <address><email></email></address>
1762    </author>
1763    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1764      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1765      <address><email></email></address>
1766    </author>
1767    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1768      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1769      <address><email></email></address>
1770    </author>
1771    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1772      <organization abbrev="W3C">World Wide Web Consortium</organization>
1773      <address><email></email></address>
1774    </author>
1775    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1776      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1777      <address><email></email></address>
1778    </author>
1779    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1780  </front>
1781  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
1782  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
1785<reference anchor="Part5">
[119]1786  <front>
1787    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
1788    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
[1106]1789      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1790      <address><email></email></address>
1791    </author>
1792    <author initials="J." surname="Gettys" fullname="Jim Gettys">
[844]1793      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1794      <address><email></email></address>
[119]1795    </author>
1796    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1797      <organization abbrev="HP">Hewlett-Packard Company</organization>
1798      <address><email></email></address>
1799    </author>
1800    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1801      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1802      <address><email></email></address>
1803    </author>
1804    <author initials="L." surname="Masinter" fullname="Larry Masinter">
[1106]1805      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1806      <address><email></email></address>
1807    </author>
1808    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1809      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1810      <address><email></email></address>
1811    </author>
1812    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1813      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1814      <address><email></email></address>
1815    </author>
1816    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1817      <organization abbrev="W3C">World Wide Web Consortium</organization>
1818      <address><email></email></address>
1819    </author>
1820    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1821      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1822      <address><email></email></address>
1823    </author>
1824    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1825  </front>
1826  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
1827  <x:source href="p5-range.xml" basename="p5-range"/>
1830<reference anchor="Part6">
[119]1831  <front>
1832    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
1833    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
[1106]1834      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1835      <address><email></email></address>
1836    </author>
1837    <author initials="J." surname="Gettys" fullname="Jim Gettys">
[844]1838      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1839      <address><email></email></address>
[119]1840    </author>
1841    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1842      <organization abbrev="HP">Hewlett-Packard Company</organization>
1843      <address><email></email></address>
1844    </author>
1845    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1846      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1847      <address><email></email></address>
1848    </author>
1849    <author initials="L." surname="Masinter" fullname="Larry Masinter">
[1106]1850      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1851      <address><email></email></address>
1852    </author>
1853    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1854      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1855      <address><email></email></address>
1856    </author>
1857    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1858      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1859      <address><email></email></address>
1860    </author>
1861    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1862      <organization abbrev="W3C">World Wide Web Consortium</organization>
1863      <address><email></email></address>
1864    </author>
[601]1865    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
[1440]1866      <organization>Rackspace</organization>
[601]1867      <address><email></email></address>
1868    </author>
[119]1869    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1870      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1871      <address><email></email></address>
1872    </author>
1873    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1874  </front>
1875  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
1876  <x:source href="p6-cache.xml" basename="p6-cache"/>
[122]1879<reference anchor="RFC1950">
1880  <front>
1881    <title>ZLIB Compressed Data Format Specification version 3.3</title>
1882    <author initials="L.P." surname="Deutsch" fullname="L. Peter Deutsch">
1883      <organization>Aladdin Enterprises</organization>
1884      <address><email></email></address>
1885    </author>
[713]1886    <author initials="J-L." surname="Gailly" fullname="Jean-Loup Gailly"/>
[122]1887    <date month="May" year="1996"/>
1888  </front>
1889  <seriesInfo name="RFC" value="1950"/>
[1477]1890  <!--<annotation>
[908]1891    RFC 1950 is an Informational RFC, thus it might be less stable than
[122]1892    this specification. On the other hand, this downward reference was
[1414]1893    present since the publication of <xref target="RFC2068" x:fmt="none">RFC 2068</xref> in 1997,
[277]1894    therefore it is unlikely to cause problems in practice. See also
1895    <xref target="BCP97"/>.
[1477]1896  </annotation>-->
[806]1899<reference anchor="RFC1951">
1900  <front>
1901    <title>DEFLATE Compressed Data Format Specification version 1.3</title>
1902    <author initials="P." surname="Deutsch" fullname="L. Peter Deutsch">
1903      <organization>Aladdin Enterprises</organization>
1904      <address><email></email></address>
1905    </author>
1906    <date month="May" year="1996"/>
1907  </front>
1908  <seriesInfo name="RFC" value="1951"/>
[1477]1909  <!--<annotation>
[908]1910    RFC 1951 is an Informational RFC, thus it might be less stable than
[806]1911    this specification. On the other hand, this downward reference was
[1414]1912    present since the publication of <xref target="RFC2068" x:fmt="none">RFC 2068</xref> in 1997,
[806]1913    therefore it is unlikely to cause problems in practice. See also
1914    <xref target="BCP97"/>.
[1477]1915  </annotation>-->
[122]1918<reference anchor="RFC1952">
1919  <front>
1920    <title>GZIP file format specification version 4.3</title>
1921    <author initials="P." surname="Deutsch" fullname="L. Peter Deutsch">
1922      <organization>Aladdin Enterprises</organization>
1923      <address><email></email></address>
1924    </author>
1925    <author initials="J-L." surname="Gailly" fullname="Jean-Loup Gailly">
1926      <address><email></email></address>
1927    </author>
1928    <author initials="M." surname="Adler" fullname="Mark Adler">
1929      <address><email></email></address>
1930    </author>
1931    <author initials="L.P." surname="Deutsch" fullname="L. Peter Deutsch">
1932      <address><email></email></address>
1933    </author>
1934    <author initials="G." surname="Randers-Pehrson" fullname="Glenn Randers-Pehrson">
1935      <address><email></email></address>
1936    </author>
1937    <date month="May" year="1996"/>
1938  </front>
1939  <seriesInfo name="RFC" value="1952"/>
[1477]1940  <!--<annotation>
[908]1941    RFC 1952 is an Informational RFC, thus it might be less stable than
[122]1942    this specification. On the other hand, this downward reference was
[1414]1943    present since the publication of <xref target="RFC2068" x:fmt="none">RFC 2068</xref> in 1997,
[277]1944    therefore it is unlikely to cause problems in practice. See also
1945    <xref target="BCP97"/>.
[1477]1946  </annotation>-->
[131]1949<reference anchor="RFC2045">
1950  <front>
1951    <title abbrev="Internet Message Bodies">Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</title>
1952    <author initials="N." surname="Freed" fullname="Ned Freed">
1953      <organization>Innosoft International, Inc.</organization>
1954      <address><email></email></address>
1955    </author>
1956    <author initials="N.S." surname="Borenstein" fullname="Nathaniel S. Borenstein">
1957      <organization>First Virtual Holdings</organization>
1958      <address><email></email></address>
1959    </author>
1960    <date month="November" year="1996"/>
1961  </front>
1962  <seriesInfo name="RFC" value="2045"/>
1965<reference anchor="RFC2046">
1966  <front>
1967    <title abbrev="Media Types">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</title>
1968    <author initials="N." surname="Freed" fullname="Ned Freed">
1969      <organization>Innosoft International, Inc.</organization>
1970      <address><email></email></address>
1971    </author>
1972    <author initials="N." surname="Borenstein" fullname="Nathaniel S. Borenstein">
1973      <organization>First Virtual Holdings</organization>
1974      <address><email></email></address>
1975    </author>
1976    <date month="November" year="1996"/>
1977  </front>
1978  <seriesInfo name="RFC" value="2046"/>
[119]1981<reference anchor="RFC2119">
1982  <front>
1983    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
1984    <author initials="S." surname="Bradner" fullname="Scott Bradner">
1985      <organization>Harvard University</organization>
1986      <address><email></email></address>
1987    </author>
1988    <date month="March" year="1997"/>
1989  </front>
1990  <seriesInfo name="BCP" value="14"/>
1991  <seriesInfo name="RFC" value="2119"/>
[303]1994<reference anchor='RFC4647'>
1995  <front>
1996    <title>Matching of Language Tags</title>
1997    <author initials='A.' surname='Phillips' fullname='Addison Phillips' role="editor">
1998      <organization>Yahoo! Inc.</organization>
1999      <address><email></email></address>
2000    </author>
2001    <author initials='M.' surname='Davis' fullname='Mark Davis' role="editor">
2002      <organization>Google</organization>
2003      <address><email></email></address>
2004    </author>
2005    <date year='2006' month='September' />
2006  </front>
2007  <seriesInfo name='BCP' value='47' />
2008  <seriesInfo name='RFC' value='4647' />
[425]2011<reference anchor="RFC5234">
2012  <front>
2013    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
2014    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
2015      <organization>Brandenburg InternetWorking</organization>
2016      <address>
[728]2017        <email></email>
2018      </address> 
[425]2019    </author>
2020    <author initials="P." surname="Overell" fullname="Paul Overell">
2021      <organization>THUS plc.</organization>
2022      <address>
[728]2023        <email></email>
2024      </address>
[425]2025    </author>
2026    <date month="January" year="2008"/>
2027  </front>
2028  <seriesInfo name="STD" value="68"/>
2029  <seriesInfo name="RFC" value="5234"/>
[690]2032<reference anchor='RFC5646'>
[613]2033  <front>
2034    <title>Tags for Identifying Languages</title>
2035    <author initials='A.' surname='Phillips' fullname='Addison Phillips' role='editor'>
2036      <organization>Lab126</organization>
2037      <address><email></email></address>
2038    </author>
2039    <author initials='M.' surname='Davis' fullname='Mark Davis' role='editor'>
2040      <organization>Google</organization>
2041      <address><email></email></address>
2042    </author>
[690]2043    <date month='September' year='2009' />
[613]2044  </front>
[690]2045  <seriesInfo name='BCP' value='47' />
2046  <seriesInfo name='RFC' value='5646' />
2051<references title="Informative References">
[129]2053<reference anchor="RFC1945">
2054  <front>
2055    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
2056    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2057      <organization>MIT, Laboratory for Computer Science</organization>
2058      <address><email></email></address>
2059    </author>
2060    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
2061      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
2062      <address><email></email></address>
2063    </author>
2064    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
2065      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
2066      <address><email></email></address>
2067    </author>
2068    <date month="May" year="1996"/>
2069  </front>
2070  <seriesInfo name="RFC" value="1945"/>
2073<reference anchor="RFC2049">
2074  <front>
2075    <title abbrev="MIME Conformance">Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples</title>
2076    <author initials="N." surname="Freed" fullname="Ned Freed">
2077      <organization>Innosoft International, Inc.</organization>
2078      <address><email></email></address>
2079    </author>
2080    <author initials="N.S." surname="Borenstein" fullname="Nathaniel S. Borenstein">
2081      <organization>First Virtual Holdings</organization>
2082      <address><email></email></address>
2083    </author>
2084    <date month="November" year="1996"/>
2085  </front>
2086  <seriesInfo name="RFC" value="2049"/>
[133]2089<reference anchor="RFC2068">
2090  <front>
2091    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
2092    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
2093      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
2094      <address><email></email></address>
2095    </author>
2096    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2097      <organization>MIT Laboratory for Computer Science</organization>
2098      <address><email></email></address>
2099    </author>
2100    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2101      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
2102      <address><email></email></address>
2103    </author>
2104    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
2105      <organization>MIT Laboratory for Computer Science</organization>
2106      <address><email></email></address>
2107    </author>
2108    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2109      <organization>MIT Laboratory for Computer Science</organization>
2110      <address><email></email></address>
2111    </author>
2112    <date month="January" year="1997"/>
2113  </front>
2114  <seriesInfo name="RFC" value="2068"/>
[129]2117<reference anchor="RFC2076">
2118  <front>
2119    <title abbrev="Internet Message Headers">Common Internet Message Headers</title>
2120    <author initials="J." surname="Palme" fullname="Jacob Palme">
2121      <organization>Stockholm University/KTH</organization>
2122      <address><email></email></address>
2123    </author>
2124    <date month="February" year="1997"/>
2125  </front>
2126  <seriesInfo name="RFC" value="2076"/>
2129<reference anchor="RFC2277">
2130  <front>
2131    <title abbrev="Charset Policy">IETF Policy on Character Sets and Languages</title>
2132    <author initials="H.T." surname="Alvestrand" fullname="Harald Tveit Alvestrand">
2133      <organization>UNINETT</organization>
2134      <address><email></email></address>
2135    </author>
2136    <date month="January" year="1998"/>
2137  </front>
2138  <seriesInfo name="BCP" value="18"/>
2139  <seriesInfo name="RFC" value="2277"/>
[745]2142<reference anchor='RFC2295'>
2143  <front>
2144    <title abbrev='HTTP Content Negotiation'>Transparent Content Negotiation in HTTP</title>
2145    <author initials='K.' surname='Holtman' fullname='Koen Holtman'>
2146      <organization>Technische Universiteit Eindhoven</organization>
2147      <address>
2148        <email></email>
2149      </address>
2150    </author>
2151    <author initials='A.H.' surname='Mutz' fullname='Andrew H. Mutz'>
2152      <organization>Hewlett-Packard Company</organization>
2153      <address>
2154        <email></email>
2155      </address>
2156    </author>
2157    <date year='1998' month='March'/>
2158  </front>
2159  <seriesInfo name='RFC' value='2295'/>
[129]2162<reference anchor="RFC2388">
2163  <front>
2164    <title abbrev="multipart/form-data">Returning Values from Forms:  multipart/form-data</title>
2165    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2166      <organization>Xerox Palo Alto Research Center</organization>
2167      <address><email></email></address>
2168    </author>
2169    <date year="1998" month="August"/>
2170  </front>
2171  <seriesInfo name="RFC" value="2388"/>
2174<reference anchor="RFC2557">
2175  <front>
2176    <title abbrev="MIME Encapsulation of Aggregate Documents">MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)</title>
2177    <author initials="F." surname="Palme" fullname="Jacob Palme">
2178      <organization>Stockholm University and KTH</organization>
2179      <address><email></email></address>
2180    </author>
2181    <author initials="A." surname="Hopmann" fullname="Alex Hopmann">
2182      <organization>Microsoft Corporation</organization>
2183      <address><email></email></address>
2184    </author>
2185    <author initials="N." surname="Shelness" fullname="Nick Shelness">
2186      <organization>Lotus Development Corporation</organization>
2187      <address><email></email></address>
2188    </author>
2189    <author initials="E." surname="Stefferud" fullname="Einar Stefferud">
2190      <address><email></email></address>
2191    </author>
2192    <date year="1999" month="March"/>
2193  </front>
2194  <seriesInfo name="RFC" value="2557"/>
[119]2197<reference anchor="RFC2616">
2198  <front>
2199    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
2200    <author initials="R." surname="Fielding" fullname="R. Fielding">
2201      <organization>University of California, Irvine</organization>
2202      <address><email></email></address>
2203    </author>
2204    <author initials="J." surname="Gettys" fullname="J. Gettys">
2205      <organization>W3C</organization>
2206      <address><email></email></address>
2207    </author>
2208    <author initials="J." surname="Mogul" fullname="J. Mogul">
2209      <organization>Compaq Computer Corporation</organization>
2210      <address><email></email></address>
2211    </author>
2212    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
2213      <organization>MIT Laboratory for Computer Science</organization>
2214      <address><email></email></address>
2215    </author>
2216    <author initials="L." surname="Masinter" fullname="L. Masinter">
2217      <organization>Xerox Corporation</organization>
2218      <address><email></email></address>
2219    </author>
2220    <author initials="P." surname="Leach" fullname="P. Leach">
2221      <organization>Microsoft Corporation</organization>
2222      <address><email></email></address>
2223    </author>
2224    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
2225      <organization>W3C</organization>
2226      <address><email></email></address>
2227    </author>
2228    <date month="June" year="1999"/>
2229  </front>
2230  <seriesInfo name="RFC" value="2616"/>
[129]2233<reference anchor="RFC3629">
2234  <front>
2235    <title>UTF-8, a transformation format of ISO 10646</title>
2236    <author initials="F." surname="Yergeau" fullname="F. Yergeau">
2237      <organization>Alis Technologies</organization>
2238      <address><email></email></address>
2239    </author>
2240    <date month="November" year="2003"/>
2241  </front>
[1003]2242  <seriesInfo name="STD" value="63"/>
[129]2243  <seriesInfo name="RFC" value="3629"/>
[253]2246<reference anchor='RFC3864'>
2247  <front>
2248    <title>Registration Procedures for Message Header Fields</title>
2249    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
2250      <organization>Nine by Nine</organization>
2251      <address><email></email></address>
2252    </author>
2253    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
2254      <organization>BEA Systems</organization>
2255      <address><email></email></address>
2256    </author>
2257    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
2258      <organization>HP Labs</organization>
2259      <address><email></email></address>
2260    </author>
2261    <date year='2004' month='September' />
2262  </front>
2263  <seriesInfo name='BCP' value='90' />
2264  <seriesInfo name='RFC' value='3864' />
[200]2267<reference anchor="RFC4288">
2268  <front>
2269    <title>Media Type Specifications and Registration Procedures</title>
2270    <author initials="N." surname="Freed" fullname="N. Freed">
2271      <organization>Sun Microsystems</organization>
2272      <address>
2273        <email></email>
2274      </address>
2275    </author>
2276    <author initials="J." surname="Klensin" fullname="J. Klensin">
2277      <address>
2278        <email></email>
2279      </address>
2280    </author>
2281    <date year="2005" month="December"/>
2282  </front>
2283  <seriesInfo name="BCP" value="13"/>
2284  <seriesInfo name="RFC" value="4288"/>
[670]2287<reference anchor='RFC5226'>
2288  <front>
2289    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
2290    <author initials='T.' surname='Narten' fullname='T. Narten'>
2291      <organization>IBM</organization>
2292      <address><email></email></address>
2293    </author>
2294    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
2295      <organization>Google</organization>
2296      <address><email></email></address>
2297    </author>
2298    <date year='2008' month='May' />
2299  </front>
2300  <seriesInfo name='BCP' value='26' />
2301  <seriesInfo name='RFC' value='5226' />
[327]2304<reference anchor="RFC5322">
2305  <front>
2306    <title>Internet Message Format</title>
2307    <author initials="P." surname="Resnick" fullname="P. Resnick">
2308      <organization>Qualcomm Incorporated</organization>
2309    </author>
2310    <date year="2008" month="October"/>
2311  </front>
2312  <seriesInfo name="RFC" value="5322"/>
[1267]2315<reference anchor="RFC6151">
2316  <front>
2317    <title>Updated Security Considerations for the MD5 Message-Digest and the HMAC-MD5 Algorithms</title>
2318    <author initials="S." surname="Turner" fullname="S. Turner"/>
2319    <author initials="L." surname="Chen" fullname="L. Chen"/>
2320    <date year="2011" month="March" />
[1308]2321  </front>
[1267]2322  <seriesInfo name="RFC" value="6151" />
[1477]2325<!--<reference anchor='BCP97'>
[277]2326  <front>
2327    <title>Handling Normative References to Standards-Track Documents</title>
2328    <author initials='J.' surname='Klensin' fullname='J. Klensin'>
2329      <address>
2330        <email></email>
2331      </address>
2332    </author>
2333    <author initials='S.' surname='Hartman' fullname='S. Hartman'>
2334      <organization>MIT</organization>
2335      <address>
2336        <email></email>
2337      </address>
2338    </author>
2339    <date year='2007' month='June' />
2340  </front>
2341  <seriesInfo name='BCP' value='97' />
2342  <seriesInfo name='RFC' value='4897' />
[1307]2345<reference anchor="RFC6266">
[1308]2346  <front>
[1259]2347    <title abbrev="Content-Disposition in HTTP">Use of the Content-Disposition Header Field
2348    in the Hypertext Transfer Protocol (HTTP)</title>
2349    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke">
2350      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2351      <address>
[1308]2352        <email></email>
[1259]2353      </address>
2354    </author>
[1307]2355    <date month="June" year="2011"/>
[1259]2356  </front>
[1307]2357  <seriesInfo name='RFC' value='6266' />
[874]2362<section title="Differences between HTTP and MIME" anchor="differences.between.http.and.mime">
[327]2364   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
[1544]2365   allow a message body to be transmitted in an open variety of
[8]2366   representations and with extensible mechanisms. However, RFC 2045
2367   discusses mail, and HTTP has a few features that are different from
[874]2368   those described in MIME. These differences were carefully chosen
[8]2369   to optimize performance over binary connections, to allow greater
2370   freedom in the use of new media types, to make date comparisons
2371   easier, and to acknowledge the practice of some early HTTP servers
2372   and clients.
[874]2375   This appendix describes specific areas where HTTP differs from MIME.
2376   Proxies and gateways to strict MIME environments &SHOULD; be
[8]2377   aware of these differences and provide the appropriate conversions
2378   where necessary. Proxies and gateways from MIME environments to HTTP
2379   also need to be aware of the differences because some conversions
2380   might be required.
[8]2383<section title="MIME-Version" anchor="mime-version">
[1120]2384  <iref primary="true" item="MIME-Version header field" x:for-anchor=""/>
2385  <iref primary="true" item="Header Fields" subitem="MIME-Version" x:for-anchor=""/>
[229]2386  <x:anchor-alias value="MIME-Version"/>
2388   HTTP is not a MIME-compliant protocol. However, HTTP/1.1 messages &MAY;
[1163]2389   include a single MIME-Version header field to indicate what
[8]2390   version of the MIME protocol was used to construct the message. Use
2391   of the MIME-Version header field indicates that the message is in
[1520]2392   full conformance with the MIME protocol (as defined in <xref target="RFC2045"/>).
2393   Proxies/gateways are responsible for ensuring full conformance (where
[8]2394   possible) when exporting HTTP messages to strict MIME environments.
[1234]2396<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="MIME-Version"/>
2397  <x:ref>MIME-Version</x:ref> = 1*<x:ref>DIGIT</x:ref> "." 1*<x:ref>DIGIT</x:ref>
2400   MIME version "1.0" is the default for use in HTTP/1.1. However,
2401   HTTP/1.1 message parsing and semantics are defined by this document
2402   and not the MIME specification.
2406<section title="Conversion to Canonical Form" anchor="">
[874]2408   MIME requires that an Internet mail body-part be converted to
[115]2409   canonical form prior to being transferred, as described in <xref target="RFC2049" x:fmt="of" x:sec="4"/>.
[97]2410   <xref target="canonicalization.and.text.defaults"/> of this document describes the forms
[8]2411   allowed for subtypes of the "text" media type when transmitted over
[97]2412   HTTP. <xref target="RFC2046"/> requires that content with a type of "text" represent
[8]2413   line breaks as CRLF and forbids the use of CR or LF outside of line
2414   break sequences. HTTP allows CRLF, bare CR, and bare LF to indicate a
2415   line break within text content when a message is transmitted over
2416   HTTP.
2419   Where it is possible, a proxy or gateway from HTTP to a strict MIME
2420   environment &SHOULD; translate all line breaks within the text media
[1176]2421   types described in <xref target="canonicalization.and.text.defaults"/>
2422   of this document to the RFC 2049
[8]2423   canonical form of CRLF. Note, however, that this might be complicated
2424   by the presence of a Content-Encoding and by the fact that HTTP
[1176]2425   allows the use of some character encodings which do not use octets 13 and
2426   10 to represent CR and LF, respectively, as is the case for some multi-byte
2427   character encodings.
[969]2430   Conversion will break any cryptographic
[8]2431   checksums applied to the original content unless the original content
2432   is already in canonical form. Therefore, the canonical form is
2433   recommended for any content that uses such checksums in HTTP.
2438<section title="Conversion of Date Formats" anchor="">
[1436]2440   HTTP/1.1 uses a restricted set of date formats (&http-date;) to
[385]2441   simplify the process of date comparison. Proxies and gateways from
2442   other protocols &SHOULD; ensure that any Date header field present in a
2443   message conforms to one of the HTTP/1.1 formats and rewrite the date
2444   if necessary.
[8]2448<section title="Introduction of Content-Encoding" anchor="introduction.of.content-encoding">
[874]2450   MIME does not include any concept equivalent to HTTP/1.1's
[8]2451   Content-Encoding header field. Since this acts as a modifier on the
2452   media type, proxies and gateways from HTTP to MIME-compliant
2453   protocols &MUST; either change the value of the Content-Type header
[874]2454   field or decode the representation before forwarding the message. (Some
[8]2455   experimental applications of Content-Type for Internet mail have used
2456   a media-type parameter of ";conversions=&lt;content-coding&gt;" to perform
2457   a function equivalent to Content-Encoding. However, this parameter is
[874]2458   not part of the MIME standards).
2462<section title="No Content-Transfer-Encoding" anchor="no.content-transfer-encoding">
[1506]2463  <iref item="Content-Transfer-Encoding header field" x:for-anchor=""/>
2464  <iref item="Header Fields" subitem="Content-Transfer-Encoding" x:for-anchor=""/>
[874]2466   HTTP does not use the Content-Transfer-Encoding field of MIME.
2467   Proxies and gateways from MIME-compliant protocols to HTTP &MUST;
[85]2468   remove any Content-Transfer-Encoding
[8]2469   prior to delivering the response message to an HTTP client.
2472   Proxies and gateways from HTTP to MIME-compliant protocols are
2473   responsible for ensuring that the message is in the correct format
2474   and encoding for safe transport on that protocol, where "safe
2475   transport" is defined by the limitations of the protocol being used.
2476   Such a proxy or gateway &SHOULD; label the data with an appropriate
2477   Content-Transfer-Encoding if doing so will improve the likelihood of
2478   safe transport over the destination protocol.
2482<section title="Introduction of Transfer-Encoding" anchor="introduction.of.transfer-encoding">
[29]2484   HTTP/1.1 introduces the Transfer-Encoding header field (&header-transfer-encoding;).
[8]2485   Proxies/gateways &MUST; remove any transfer-coding prior to
2486   forwarding a message via a MIME-compliant protocol.
2490<section title="MHTML and Line Length Limitations" anchor="mhtml.line.length">
[129]2492   HTTP implementations which share code with MHTML <xref target="RFC2557"/> implementations
[8]2493   need to be aware of MIME line length limitations. Since HTTP does not
2494   have this limitation, HTTP does not fold long lines. MHTML messages
2495   being transported by HTTP follow all conventions of MHTML, including
2496   line length limitations and folding, canonicalization, etc., since
2497   HTTP transports all message-bodies as payload (see <xref target="multipart.types"/>) and
2498   does not interpret the content or any MIME header lines that might be
2499   contained therein.
2504<section title="Additional Features" anchor="additional.features">
[97]2506   <xref target="RFC1945"/> and <xref target="RFC2068"/> document protocol elements used by some
[8]2507   existing HTTP implementations, but not consistently and correctly
2508   across most HTTP/1.1 applications. Implementors are advised to be
2509   aware of these features, but cannot rely upon their presence in, or
2510   interoperability with, other HTTP/1.1 applications. Some of these
2511   describe proposed experimental features, and some describe features
2512   that experimental deployment found lacking that are now addressed in
2513   the base HTTP/1.1 specification.
[994]2516   A number of other header fields, such as Content-Disposition and Title,
[1307]2517   from SMTP and MIME are also often implemented (see <xref target="RFC6266"/>
2518   and <xref target="RFC2076"/>).
[99]2522<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
2524  Clarify contexts that charset is used in.
2525  (<xref target="character.sets"/>)
[1240]2528  Remove the default character encoding for text media types; the default
2529  now is whatever the media type definition says.
2530  (<xref target="canonicalization.and.text.defaults"/>)
[1234]2533  Change ABNF productions for header fields to only define the field value.
[1415]2534  (<xref target="header.field.definitions"/>)
[1308]2537  Remove definition of Content-MD5 header field because it was inconsistently
2538  implemented with respect to partial responses, and also because of known
2539  deficiencies in the hash algorithm itself (see <xref target="RFC6151"/> for details).
[1415]2540  (<xref target="header.field.definitions"/>)
[1240]2543  Remove ISO-8859-1 special-casing in Accept-Charset.
2544  (<xref target="header.accept-charset"/>)
[712]2547  Remove base URI setting semantics for Content-Location due to poor
[714]2548  implementation support, which was caused by too many broken servers emitting
[994]2549  bogus Content-Location header fields, and also the potentially undesirable effect
[714]2550  of potentially breaking relative links in content-negotiated resources.
[712]2551  (<xref target="header.content-location"/>)
[1308]2554  Remove discussion of Content-Disposition header field, it is now defined
2555  by <xref target="RFC6266"/>.
[1259]2556  (<xref target="additional.features"/>)
[104]2559  Remove reference to non-existant identity transfer-coding value tokens.
2560  (<xref target="no.content-transfer-encoding"/>)
[680]2564<?BEGININC p3-payload.abnf-appendix ?>
[427]2565<section xmlns:x="" title="Collected ABNF" anchor="collected.abnf">
2567<artwork type="abnf" name="p3-payload.parsed-abnf">
[1234]2568<x:ref>Accept</x:ref> = [ ( "," / ( media-range [ accept-params ] ) ) *( OWS "," [
2569 OWS media-range [ accept-params ] ] ) ]
2570<x:ref>Accept-Charset</x:ref> = *( "," OWS ) ( charset / "*" ) [ OWS ";" OWS "q="
[425]2571 qvalue ] *( OWS "," [ OWS ( charset / "*" ) [ OWS ";" OWS "q="
2572 qvalue ] ] )
[1234]2573<x:ref>Accept-Encoding</x:ref> = [ ( "," / ( codings [ OWS ";" OWS "q=" qvalue ] ) )
2574 *( OWS "," [ OWS codings [ OWS ";" OWS "q=" qvalue ] ] ) ]
2575<x:ref>Accept-Language</x:ref> = *( "," OWS ) language-range [ OWS ";" OWS "q="
[425]2576 qvalue ] *( OWS "," [ OWS language-range [ OWS ";" OWS "q=" qvalue ]
2577 ] )
[1234]2579<x:ref>Content-Encoding</x:ref> = *( "," OWS ) content-coding *( OWS "," [ OWS
[425]2580 content-coding ] )
[1234]2581<x:ref>Content-Language</x:ref> = *( "," OWS ) language-tag *( OWS "," [ OWS
[425]2582 language-tag ] )
[1234]2583<x:ref>Content-Location</x:ref> = absolute-URI / partial-URI
2584<x:ref>Content-Type</x:ref> = media-type
[1234]2586<x:ref>MIME-Version</x:ref> = 1*DIGIT "." 1*DIGIT
[1523]2588<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 3.2.1&gt;
[1318]2590<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.7&gt;
[810]2591<x:ref>accept-ext</x:ref> = OWS ";" OWS token [ "=" word ]
[427]2592<x:ref>accept-params</x:ref> = OWS ";" OWS "q=" qvalue *accept-ext
2593<x:ref>attribute</x:ref> = token
2595<x:ref>charset</x:ref> = token
[1410]2596<x:ref>codings</x:ref> = content-coding / "identity" / "*"
[427]2597<x:ref>content-coding</x:ref> = token
[427]2599<x:ref>language-range</x:ref> = &lt;language-range, defined in [RFC4647], Section 2.1&gt;
[690]2600<x:ref>language-tag</x:ref> = &lt;Language-Tag, defined in [RFC5646], Section 2.1&gt;
2602<x:ref>media-range</x:ref> = ( "*/*" / ( type "/*" ) / ( type "/" subtype ) ) *( OWS
[425]2603 ";" OWS parameter )
[427]2604<x:ref>media-type</x:ref> = type "/" subtype *( OWS ";" OWS parameter )
2606<x:ref>parameter</x:ref> = attribute "=" value
[1318]2607<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.7&gt;
[1436]2609<x:ref>qvalue</x:ref> = &lt;qvalue, defined in [Part1], Section 5.3&gt;
2611<x:ref>subtype</x:ref> = token
[1523]2613<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 3.2.4&gt;
[427]2614<x:ref>type</x:ref> = token
[810]2616<x:ref>value</x:ref> = word
[1523]2618<x:ref>word</x:ref> = &lt;word, defined in [Part1], Section 3.2.4&gt;
[532]2621<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
2622; Accept defined but not used
[425]2623; Accept-Charset defined but not used
2624; Accept-Encoding defined but not used
2625; Accept-Language defined but not used
[968]2626; Content-Encoding defined but not used
2627; Content-Language defined but not used
2628; Content-Location defined but not used
2629; Content-Type defined but not used
[425]2630; MIME-Version defined but not used
[680]2632<?ENDINC p3-payload.abnf-appendix ?>
[252]2634<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
[1002]2636<section title="Since RFC 2616">
2638  Extracted relevant partitions from <xref target="RFC2616"/>.
2642<section title="Since draft-ietf-httpbis-p3-payload-00">
[116]2644  Closed issues:
2645  <list style="symbols">
2646    <t>
[324]2647      <eref target=""/>:
[116]2648      "Media Type Registrations"
2649      (<eref target=""/>)
2650    </t>
2651    <t>
[324]2652      <eref target=""/>:
[116]2653      "Clarification regarding quoting of charset values"
2654      (<eref target=""/>)
2655    </t>
2656    <t>
[324]2657      <eref target=""/>:
[116]2658      "Remove 'identity' token references"
2659      (<eref target=""/>)
2660    </t>
2661    <t>
[324]2662      <eref target=""/>:
[126]2663      "Accept-Encoding BNF"
2664    </t>
2665    <t>
[324]2666      <eref target=""/>:
[152]2667      "Normative and Informative references"
2668    </t>
2669    <t>
[324]2670      <eref target=""/>:
[116]2671      "RFC1700 references"
2672    </t>
[122]2673    <t>
[324]2674      <eref target=""/>:
[200]2675      "Updating to RFC4288"
2676    </t>
2677    <t>
[324]2678      <eref target=""/>:
[129]2679      "Informative references"
2680    </t>
2681    <t>
[324]2682      <eref target=""/>:
[123]2683      "ISO-8859-1 Reference"
2684    </t>
2685    <t>
[324]2686      <eref target=""/>:
[122]2687      "Encoding References Normative"
2688    </t>
[131]2689    <t>
[324]2690      <eref target=""/>:
[131]2691      "Normative up-to-date references"
2692    </t>
[116]2693  </list>
[170]2697<section title="Since draft-ietf-httpbis-p3-payload-01">
[324]2699  Ongoing work on ABNF conversion (<eref target=""/>):
[205]2700  <list style="symbols">
2701    <t>
2702      Add explicit references to BNF syntax and rules imported from other parts of the specification.
2703    </t>
2704  </list>
[252]2708<section title="Since draft-ietf-httpbis-p3-payload-02" anchor="changes.since.02">
[232]2710  Closed issues:
2711  <list style="symbols">
2712    <t>
[324]2713      <eref target=""/>:
[251]2714      "Quoting Charsets"
2715    </t>
2716    <t>
[324]2717      <eref target=""/>:
[232]2718      "Classification for Allow header"
2719    </t>
[248]2720    <t>
[324]2721      <eref target=""/>:
[248]2722      "missing default for qvalue in description of Accept-Encoding"
2723    </t>
[232]2724  </list>
[994]2727  Ongoing work on IANA Message Header Field Registration (<eref target=""/>):
[253]2728  <list style="symbols">
2729    <t>
[994]2730      Reference RFC 3984, and update header field registrations for headers defined
[253]2731      in this document.
2732    </t>
2733  </list>
[267]2737<section title="Since draft-ietf-httpbis-p3-payload-03" anchor="changes.since.03">
[269]2739  Closed issues:
2740  <list style="symbols">
2741    <t>
[297]2742      <eref target=""/>:
2743      "Quoting Charsets"
2744    </t>
2745    <t>
[303]2746      <eref target=""/>:
2747      "language tag matching (Accept-Language) vs RFC4647"
2748    </t>
2749    <t>
[277]2750      <eref target=""/>:
[269]2751      "RFC 1806 has been replaced by RFC2183"
2752    </t>
2753  </list>
2756  Other changes:
2757  <list style="symbols">
2758    <t>
2759      <eref target=""/>:
[1101]2760      "Encoding References Normative" &mdash; rephrase the annotation and reference
[1477]2761      BCP97.
[277]2762    </t>
2763  </list>
[269]2765 </section>
[323]2767<section title="Since draft-ietf-httpbis-p3-payload-04" anchor="changes.since.04">
[327]2769  Closed issues:
2770  <list style="symbols">
2771    <t>
2772      <eref target=""/>:
2773      "RFC 2822 is updated by RFC 5322"
2774    </t>
2775  </list>
2778  Ongoing work on ABNF conversion (<eref target=""/>):
2779  <list style="symbols">
2780    <t>
2781      Use "/" instead of "|" for alternatives.
2782    </t>
[357]2783    <t>
2784      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
2785      whitespace ("OWS") and required whitespace ("RWS").
2786    </t>
2787    <t>
2788      Rewrite ABNFs to spell out whitespace rules, factor out
[994]2789      header field value format definitions.
[357]2790    </t>
[334]2791  </list>
[382]2795<section title="Since draft-ietf-httpbis-p3-payload-05" anchor="changes.since.05">
[385]2797  Closed issues:
2798  <list style="symbols">
2799    <t>
2800      <eref target=""/>:
2801      "Join "Differences Between HTTP Entities and RFC 2045 Entities"?"
2802    </t>
2803  </list>
[543]2806  Final work on ABNF conversion (<eref target=""/>):
[421]2807  <list style="symbols">
2808    <t>
[424]2809      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
[421]2810    </t>
2811  </list>
2814  Other changes:
2815  <list style="symbols">
2816    <t>
2817      Move definition of quality values into Part 1.
2818    </t>
2819  </list>
[547]2823<section title="Since draft-ietf-httpbis-p3-payload-06" anchor="changes.since.06">
[577]2825  Closed issues:
2826  <list style="symbols">
2827    <t>
2828      <eref target=""/>:
2829      "Content-Location isn't special"
2830    </t>
[592]2831    <t>
2832      <eref target=""/>:
2833      "Content Sniffing"
2834    </t>
[577]2835  </list>
[604]2839<section title="Since draft-ietf-httpbis-p3-payload-07" anchor="changes.since.07">
[613]2841  Closed issues:
2842  <list style="symbols">
2843    <t>
[670]2844      <eref target=""/>:
[613]2845      "Updated reference for language tags"
2846    </t>
[663]2847    <t>
[716]2848      <eref target=""/>:
2849      "Clarify rules for determining what entities a response carries"
2850    </t>
2851    <t>
[712]2852      <eref target=""/>:
2853      "Content-Location base-setting problems"
2854    </t>
2855    <t>
[663]2856      <eref target=""/>:
2857      "Content Sniffing"
2858    </t>
[670]2859    <t>
2860      <eref target=""/>:
2861      "pick IANA policy (RFC5226) for Transfer Coding / Content Coding"
2862    </t>
[673]2863    <t>
2864      <eref target=""/>:
2865      "move definitions of gzip/deflate/compress to part 1"
2866    </t>
[613]2867  </list>
2870  Partly resolved issues:
2871  <list style="symbols">
2872    <t>
2873      <eref target=""/>:
2874      "update IANA requirements wrt Transfer-Coding values" (add the
2875      IANA Considerations subsection)
2876    </t>
[668]2877    <t>
2878      <eref target=""/>:
2879      "update IANA requirements wrt Content-Coding values" (add the
2880      IANA Considerations subsection)
2881    </t>
[667]2882  </list>
[720]2886<section title="Since draft-ietf-httpbis-p3-payload-08" anchor="changes.since.08">
[724]2888  Closed issues:
2889  <list style="symbols">
2890    <t>
[745]2891      <eref target=""/>:
2892      "Content Negotiation for media types"
2893    </t>
2894    <t>
[724]2895      <eref target=""/>:
2896      "Accept-Language: which RFC4647 filtering?"
2897    </t>
2898  </list>
[773]2902<section title="Since draft-ietf-httpbis-p3-payload-09" anchor="changes.since.09">
[808]2904  Closed issues:
2905  <list style="symbols">
2906    <t>
[937]2907      <eref target=""/>:
2908      "MIME-Version not listed in P1, general header fields"
2909    </t>
2910    <t>
[808]2911      <eref target=""/>:
2912      "IANA registry for content/transfer encodings"
2913    </t>
[810]2914    <t>
[831]2915      <eref target=""/>:
2916      "Content Sniffing"
2917    </t>
2918    <t>
[810]2919      <eref target=""/>:
2920      "use of term "word" when talking about header structure"
2921    </t>
[808]2922  </list>
2925  Partly resolved issues:
2926  <list style="symbols">
2927    <t>
2928      <eref target=""/>:
2929      "Term for the requested resource's URI"
2930    </t>
2931  </list>
[841]2935<section title="Since draft-ietf-httpbis-p3-payload-10" anchor="changes.since.10">
[854]2937  Closed issues:
2938  <list style="symbols">
2939    <t>
[858]2940      <eref target=""/>:
2941      "Clarify 'Requested Variant'"
2942    </t>
2943    <t>
2944      <eref target=""/>:
2945      "Content-Location isn't special"
2946    </t>
2947    <t>
[854]2948      <eref target=""/>:
2949      "Delimiting messages with multipart/byteranges"
2950    </t>
[858]2951    <t>
2952      <eref target=""/>:
2953      "Clarify entity / representation / variant terminology"
2954    </t>
2955    <t>
2956      <eref target=""/>:
2957      "confusing req. language for Content-Location"
2958    </t>
2959    <t>
2960      <eref target=""/>:
2961      "Content-Location on 304 responses"
2962    </t>
[882]2963    <t>
2964      <eref target=""/>:
2965      "'requested resource' in content-encoding definition"
2966    </t>
[911]2967    <t>
2968      <eref target=""/>:
2969      "consider removing the 'changes from 2068' sections"
2970    </t>
[854]2971  </list>
2974  Partly resolved issues:
2975  <list style="symbols">
2976    <t>
2977      <eref target=""/>:
2978      "Content-MD5 and partial responses"
2979    </t>
2980  </list>
[973]2984<section title="Since draft-ietf-httpbis-p3-payload-11" anchor="changes.since.11">
[987]2986  Closed issues:
2987  <list style="symbols">
2988    <t>
2989      <eref target=""/>:
2990      "Factor out Content-Disposition"
2991    </t>
2992  </list>
[1052]2996<section title="Since draft-ietf-httpbis-p3-payload-12" anchor="changes.since.12">
[1153]2998  Closed issues:
2999  <list style="symbols">
3000    <t>
[1165]3001      <eref target=""/>:
3002      "Header Classification"
3003    </t>
3004    <t>
[1167]3005      <eref target=""/>:
3006      "untangle ABNFs for header fields"
3007    </t>
3008    <t>
[1153]3009      <eref target=""/>:
3010      "potentially misleading MAY in media-type def"
3011    </t>
3012  </list>
[1180]3016<section title="Since draft-ietf-httpbis-p3-payload-13" anchor="changes.since.13">
[1234]3018  Closed issues:
3019  <list style="symbols">
3020    <t>
[1240]3021      <eref target=""/>:
3022      "Default charsets for text media types"
3023    </t>
3024    <t>
[1267]3025      <eref target=""/>:
3026      "Content-MD5 and partial responses"
3027    </t>
3028    <t>
[1234]3029      <eref target=""/>:
3030      "untangle ABNFs for header fields"
3031    </t>
[1244]3032    <t>
3033      <eref target=""/>:
3034      "confusing undefined parameter in media range example"
3035    </t>
[1234]3036  </list>
[1271]3040<section title="Since draft-ietf-httpbis-p3-payload-14" anchor="changes.since.14">
[1328]3042  None.
[1326]3046<section title="Since draft-ietf-httpbis-p3-payload-15" anchor="changes.since.15">
[1335]3048  Closed issues:
3049  <list style="symbols">
3050    <t>
3051      <eref target=""/>:
3052      "Strength of requirements on Accept re: 406"
3053    </t>
3054  </list>
[1401]3058<section title="Since draft-ietf-httpbis-p3-payload-16" anchor="changes.since.16">
[1452]3060  Closed issues:
3061  <list style="symbols">
3062    <t>
3063      <eref target=""/>:
3064      "Document HTTP's error-handling philosophy"
3065    </t>
3066  </list>
[1467]3070<section title="Since draft-ietf-httpbis-p3-payload-17" anchor="changes.since.17">
[1477]3072  Closed issues:
3073  <list style="symbols">
3074    <t>
3075      <eref target=""/>:
3076      "intended maturity level vs normative references"
3077    </t>
3078  </list>
[1499]3082<section title="Since draft-ietf-httpbis-p3-payload-18" anchor="changes.since.18">
3084  None yet.
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