One document matched: draft-reschke-rfc2231-in-http-08.xml
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<?rfc toc="yes"?>
<?rfc symrefs="yes"?>
<?rfc sortrefs="yes"?>
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<?rfc-ext allow-markup-in-artwork="yes" ?><rfc xmlns:x="http://purl.org/net/xml2rfc/ext" xmlns:ed="http://greenbytes.de/2002/rfcedit" ipr="trust200902" docName="draft-reschke-rfc2231-in-http-08" category="std" x:maturity-level="proposed" xml:lang="en">
<front>
<title abbrev="RFC2231 Encoding in HTTP">Application of RFC 2231
Encoding to Hypertext Transfer Protocol (HTTP) Header Fields</title>
<author initials="J. F." surname="Reschke" fullname="Julian F. Reschke">
<organization abbrev="greenbytes">greenbytes GmbH</organization>
<address>
<postal>
<street>Hafenweg 16</street>
<city>Muenster</city><region>NW</region><code>48155</code>
<country>Germany</country>
</postal>
<email>julian.reschke@greenbytes.de</email>
<uri>http://greenbytes.de/tech/webdav/</uri>
</address>
</author>
<date month="January" year="2010" day="19"/>
<abstract>
<t>
By default, message header field parameters in Hypertext Transfer Protocol (HTTP) messages
can not carry characters outside the ISO-8859-1 character set. RFC 2231
defines an escaping mechanism for use in Multipurpose Internet Mail Extensions
(MIME) headers. This document specifies a profile of that encoding
suitable for use in HTTP header fields.
</t>
</abstract>
<note title="Editorial Note (To be removed by RFC Editor before publication)">
<t>
There are multiple HTTP header fields that already use RFC 2231 encoding
in practice (Content-Disposition) or might use it in the future
(Link). The purpose of this document is to provide a single place where
the generic aspects of RFC 2231 encoding in HTTP header fields are defined.
</t>
<t>
Distribution of this document is unlimited. Although this is not a work
item of the HTTPbis Working Group, comments should be sent to the
Hypertext Transfer Protocol (HTTP) mailing list at <eref target="mailto:ietf-http-wg@w3.org">ietf-http-wg@w3.org</eref>,
which may be joined by sending a message with subject
"subscribe" to <eref target="mailto:ietf-http-wg-request@w3.org?subject=subscribe">ietf-http-wg-request@w3.org</eref>.
</t>
<t>
Discussions of the HTTPbis Working Group are archived at
<eref target="http://lists.w3.org/Archives/Public/ietf-http-wg/"/>.
</t>
<t>
XML versions, latest edits and the issues list for this document
are available from <eref target="http://greenbytes.de/tech/webdav/#draft-reschke-rfc2231-in-http"/>.
A collection of test cases is available at <eref target="http://greenbytes.de/tech/tc2231/"/>.
</t>
<x:note>
<t>
<x:h>Note:</x:h> as of January 2010, there were at least three independent
implementations of the encoding defined in <xref target="character.set.and.language.information"/>:
Konqueror (trunk), Mozilla Firefox, and Opera.
</t>
</x:note>
</note>
</front>
<middle>
<section title="Introduction" anchor="introduction">
<t>
By default, message header field parameters in HTTP (<xref target="RFC2616"/>) messages
can not carry characters outside the ISO-8859-1 character set (<xref target="ISO-8859-1"/>). RFC 2231
(<xref target="RFC2231"/>) defines an escaping mechanism for use in MIME headers.
This document specifies a profile of that encoding for use in HTTP header fields.
</t>
<x:note>
<t>
<x:h>Note:</x:h> this profile does not apply to message payloads
transmitted over HTTP, such as when using the media type "multipart/form-data"
(<xref target="RFC2388"/>).
</t>
</x:note>
</section>
<section title="Notational Conventions">
<t>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document
are to be interpreted as described in <xref target="RFC2119"/>.
</t>
<t>
This specification uses the ABNF (Augmented Backus-Naur Form) notation defined in
<xref target="RFC5234"/>. The following core rules are included by
reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
ALPHA (letters), DIGIT (decimal 0-9), HEXDIG (hexadecimal 0-9/A-F/a-f) and
LWSP (linear white space).
</t>
<t>
Note that this specification uses the term "character set" for consistency
with other IETF specifications such as RFC 2277 (see <xref target="RFC2277" x:fmt="," x:sec="3"/>). A more accurate term would be "character
encoding" (a mapping of code points to octet sequences).
</t>
</section>
<section title="A Profile of RFC 2231 for Use in HTTP">
<t>
RFC 2231 defines several extensions to MIME. The sections below discuss
if and how they apply to HTTP.
</t>
<t>
In short:
<list style="symbols">
<t>Parameter Continuations aren't needed (<xref target="parameter.continuations"/>),</t>
<t>Character Set and Language Information are useful, therefore a simple subset
is specified (<xref target="character.set.and.language.information"/>), and</t>
<t>Language Specifications in Encoded Words aren't needed (<xref target="language.specification.in.encoded.words"/>).</t>
</list>
</t>
<section title="Parameter Continuations" anchor="parameter.continuations">
<t>
<xref target="RFC2231" x:fmt="of" x:sec="3"/> defines a mechanism that
deals with the length limitations that apply to MIME headers. These
limitations do not apply to HTTP (<xref target="RFC2616" x:fmt="," x:sec="19.4.7"/>).
</t>
<t>
Thus in HTTP, senders <bcp14 xmlns="http://purl.org/net/xml2rfc/ext">MUST NOT</bcp14> use parameter continuations, and
therefore recipients do not need to support them.
</t>
</section>
<section title="Parameter Value Character Set and Language Information" anchor="character.set.and.language.information">
<t>
<xref target="RFC2231" x:fmt="of" x:sec="4"/> specifies how to embed
language information into parameter values, and also how to encode
non-ASCII characters, dealing with restrictions both in MIME and HTTP
header parameters.
</t>
<t>
However, RFC 2231 does not specify a mandatory-to-implement character set,
making it hard for senders to decide which character set to use.
Thus, recipients implementing this specification <bcp14 xmlns="http://purl.org/net/xml2rfc/ext">MUST</bcp14> support the
character sets "ISO-8859-1" <xref target="ISO-8859-1"/> and "UTF-8"
<xref target="RFC3629"/>.
</t>
<t>
Furthermore, RFC 2231 allows leaving out the character set information.
The profile defined by this specification does not allow that.
</t>
<t>
The syntax for parameters is defined in <xref target="RFC2616" x:fmt="of" x:sec="3.6"/>
(with RFC 2616 implied LWS translated to RFC 5234 LWSP):
</t>
<figure><artwork type="inline">
parameter = attribute LWSP "=" LWSP value
</artwork></figure>
<figure><artwork type="abnf"> attribute = token
value = token / quoted-string
quoted-string = <quoted-string, defined in <xref target="RFC2616" x:fmt="," x:sec="2.2"/>>
token = <token, defined in <xref target="RFC2616" x:fmt="," x:sec="2.2"/>>
</artwork></figure>
<t anchor="bnf">
<x:anchor-alias value="ext-value"/>
This specification extends the grammar to:
</t>
<figure><artwork type="abnf">
parameter = reg-parameter / ext-parameter
reg-parameter = attribute LWSP "=" LWSP value
ext-parameter = attribute "*" LWSP "=" LWSP ext-value
ext-value = charset "'" [ language ] "'" value-chars
; extended-initial-value,
; defined in <xref target="RFC2231" x:fmt="," x:sec="7"/>
charset = "UTF-8" / "ISO-8859-1" / mime-charset
mime-charset = 1*mime-charsetc
mime-charsetc = ALPHA / DIGIT
/ "!" / "#" / "$" / "%" / "&"
/ "+" / "-" / "^" / "_" / "`"
/ "{" / "}" / "~"
; as <mime-charset> in <xref target="RFC2978" x:fmt="of" x:sec="2.3"/>
; except that the single quote is not included
language = <Language-Tag, defined in <xref target="RFC5646" x:fmt="," x:sec="2.1"/>>
value-chars = *( pct-encoded / attr-char )
pct-encoded = "%" HEXDIG HEXDIG
; see <xref target="RFC3986" x:fmt="," x:sec="2.1"/>
attr-char = ALPHA / DIGIT
/ "-" / "." / "_" / "~" / ":"
/ "!" / "$" / "&" / "+"
</artwork></figure>
<t>
Thus, a parameter is either regular parameter (reg-parameter), as previously
defined in <xref target="RFC2616" x:fmt="of" x:sec="3.6"/>, or an extended
parameter (ext-parameter).
</t>
<t>
Extended parameters are those where the left hand side of the assignment
ends with an asterisk character.
</t>
<t>
The value part of an extended parameter (ext-value) is a token that consists
of three parts: the <bcp14 xmlns="http://purl.org/net/xml2rfc/ext">REQUIRED</bcp14> character set name (charset), the <bcp14 xmlns="http://purl.org/net/xml2rfc/ext">OPTIONAL</bcp14>
language information (language), and a character sequence representing the
actual value (value-chars), separated by single quote
characters. Note that both character set names and
language tags are restricted to the US-ASCII character set, and are matched
case-insensitively (see <xref target="RFC2978" x:fmt="," x:sec="2.3"/> and
<xref target="RFC5646" x:fmt="," x:sec="2.1.1"/>).
</t>
<t>
Inside the value part, characters not contained in attr-char are
encoded into an octet sequence using the specified character set. That octet
sequence then is percent-encoded as specified in <xref target="RFC3986" x:fmt="of" x:sec="2.1"/>.
</t>
<t>
Producers <bcp14 xmlns="http://purl.org/net/xml2rfc/ext">MUST NOT</bcp14> use character sets other than "UTF-8" (<xref target="RFC3629"/>)
or "ISO-8859-1" (<xref target="ISO-8859-1"/>).
Extension character sets (ext-charset) are reserved for future use.
</t>
<x:note>
<t>
<x:h>Note: </x:h> recipients should be prepared to handle encoding
errors, such as malformed or incomplete percent escape sequences, or
non-decodable octet sequences, in a robust manner. This specification
does not mandate any specific behavior, for instance the following
strategies are all acceptable:
<list style="symbols">
<t>ignoring the parameter,</t>
<t>stripping a non-decodable octet sequence,</t>
<t>substituting a non-decodable octet sequence by a replacement
character, such as the Unicode character U+FFFD (Replacement Character).</t>
</list>
</t>
</x:note>
<x:note>
<t>
<x:h>Note: </x:h> the <mime-charset> ABNF defined here differs from
the one in <xref target="RFC2978" x:fmt="of" x:sec="2.3"/> in that it does
not allow the single quote character (see also <eref target="http://www.rfc-editor.org/errata_search.php?eid=1912">RFC Editor Errata ID 1912</eref>). In practice, no character set names
using that character have been registered at the time of this writing.
</t>
</x:note>
<section title="Examples" anchor="examples">
<figure>
<preamble>
Non-extended notation, using "token":
</preamble>
<artwork type="example">
foo: bar; title=Economy
</artwork></figure>
<figure>
<preamble>
Non-extended notation, using "quoted-string":
</preamble>
<artwork type="example">
foo: bar; title="US-$ rates"
</artwork></figure>
<figure>
<preamble>
Extended notation, using the unicode character U+00A3 (POUND SIGN):
</preamble>
<artwork type="example">
foo: bar; title*=iso-8859-1'en'<x:highlight>%A3</x:highlight>%20rates
</artwork>
<postamble>
<x:h>Note</x:h>: the Unicode pound sign character U+00A3 was encoded using
ISO-8859-1 into the single octet A3, then percent-encoded. Also note
that the space character was encoded as %20, as it is not contained in
attr-char.
</postamble>
</figure>
<figure>
<preamble>
Extended notation, using the unicode characters U+00A3 (POUND SIGN)
and U+20AC (EURO SIGN):
</preamble>
<artwork type="example">
foo: bar; title*=UTF-8''<x:highlight>%c2%a3</x:highlight>%20and%20<x:highlight>%e2%82%ac</x:highlight>%20rates
</artwork>
<postamble>
<x:h>Note</x:h>: the unicode pound sign character U+00A3 was encoded using
UTF-8 into the octet sequence C2 A3, then percent-encoded. Likewise,
the unicode euro sign character U+20AC was encoded into the octet
sequence E2 82 AC, then percent-encoded. Also note that HEXDIG allows
both lower-case and upper-case character, so recipients must understand
both, and that the language information is optional, while the character
set is not.
</postamble>
</figure>
</section>
</section>
<section title="Language specification in Encoded Words" anchor="language.specification.in.encoded.words">
<t>
<xref target="RFC2231" x:fmt="of" x:sec="5"/> extends the encoding
defined in <xref target="RFC2047"/> to also support language specification
in encoded words.
Although the HTTP/1.1 specification does refer to RFC 2047
(<xref target="RFC2616" x:fmt="," x:sec="2.2"/>),
it's not clear to which header field exactly it applies, and whether it is
implemented in practice (see <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/111"/>
for details).
</t>
<t>
Thus, the RFC 2231 profile defined by this specification does not include
this feature.
</t>
</section>
</section>
<section title="Guidelines for Usage in HTTP Header Field Definitions">
<t>
Specifications of HTTP header fields that use the extensions defined
in <xref target="character.set.and.language.information"/> should clearly
state that. A simple way to achieve this is to normatively reference
this specification, and to include the <x:ref>ext-value</x:ref>
production into the ABNF for that header field.
</t>
<figure><preamble>For instance:</preamble>
<artwork type="example">
foo-header = "foo" LWSP ":" LWSP token ";" LWSP title-param
title-param = "title" LWSP "=" LWSP value
/ "title*" LWSP "=" LWSP ext-value
ext-value = <see RFCxxxx, <xref target="character.set.and.language.information"/>>
</artwork></figure>
<t>
<cref anchor="rfcno">Note to RFC Editor: in the figure above, please replace "xxxx" by the
RFC number assigned to this specification.</cref>
</t>
<section title="When to Use the Extension">
<t>
<xref target="RFC2277" x:fmt="of" x:sec="4.2"/> requires that protocol
elements containing text can carry language information. Thus, the <x:ref>ext-value</x:ref>
production should always be used when the parameter value is of textual
nature.
</t>
<t>
Furthermore, the extension should also be used whenever the parameter value
needs to carry characters not present in the US-ASCII (<xref target="USASCII"/>)
character set (note that it would be unacceptable to define a new parameter that
would be restricted to a subset of the Unicode character set).
</t>
</section>
<section title="Error Handling">
<t>
Header specifications that include parameters should also specify whether
same-named parameters can occur multiple times. If repetitions are not
allowed (and this is believed to be the common case), the specification
should state whether regular or the extended syntax takes precedence.
In the latter case, this could be used by producers to use both formats
without breaking recipients that do not understand the syntax.
</t>
<figure><preamble>Example:</preamble>
<artwork type="example">
foo: bar; title="EURO exchange rates";
title*=utf-8''<x:highlight>%e2%82%ac</x:highlight>%20exchange%20rates
</artwork>
<postamble>In this case, the sender provides an ASCII version of the title
for legacy recipients, but also includes an internationalized version for
recipients understanding this specification -- the latter obviously
should prefer the new syntax over the old one.</postamble>
</figure>
<x:note>
<t>
<x:h>Note:</x:h> at the time of this writing, many implementations failed
to ignore the form they do not understand, or prioritize the ASCII form
although the extended syntax was present.
</t>
</x:note>
</section>
<section title="Using Multiple Instances for Internationalization">
<t>
It is expected that in many cases, internationalization of parameters in response headers
is implemented using server driven content negotiation (<xref target="RFC2616" x:fmt="," x:sec="12.1"/>)
using the Accept-Language header (<xref target="RFC2616" x:fmt="," x:sec="14.4"/>).
However, the format described in this specification also allows to use
multiple instances providing multiple languages in a single header.
Specifications that want to take advantage of this should clearly specify
the expected processing by the recipient.
</t>
<figure><preamble>Example:</preamble>
<artwork type="example">
foo: bar; title*=utf-8'<x:highlight>en</x:highlight>'Document%20Title;
title*=utf-8'<x:highlight>de</x:highlight>'Titel%20des%20Dokuments
</artwork></figure>
</section>
</section>
<section title="Security Considerations" anchor="security.considerations">
<t>
This document does not discuss security issues and is not believed to raise
any security issues not already endemic in HTTP.
</t>
</section>
<section title="IANA Considerations" anchor="iana.considerations">
<t>
There are no IANA Considerations related to this specification.
</t>
</section>
<section title="Acknowledgements">
<t>
Thanks to Martin Duerst and Frank Ellermann for help figuring out ABNF details, and to
Roar Lauritzsen for implementer's feedback.
</t>
</section>
</middle>
<back>
<references title="Normative References">
<reference anchor="RFC2119">
<front>
<title abbrev="RFC Key Words">Key words for use in RFCs to Indicate Requirement Levels</title>
<author initials="S." surname="Bradner" fullname="Scott Bradner">
<organization>Harvard University</organization>
<address><email>sob@harvard.edu</email></address>
</author>
<date month="March" year="1997"/>
<area>General</area>
<keyword>keyword</keyword>
</front>
<seriesInfo name="BCP" value="14"/>
<seriesInfo name="RFC" value="2119"/>
</reference>
<reference anchor="RFC2616">
<front>
<title>Hypertext Transfer Protocol -- HTTP/1.1</title>
<author initials="R." surname="Fielding" fullname="R. Fielding">
<organization>University of California, Irvine</organization>
<address><email>fielding@ics.uci.edu</email></address>
</author>
<author initials="J." surname="Gettys" fullname="J. Gettys">
<organization>W3C</organization>
<address><email>jg@w3.org</email></address>
</author>
<author initials="J." surname="Mogul" fullname="J. Mogul">
<organization>Compaq Computer Corporation</organization>
<address><email>mogul@wrl.dec.com</email></address>
</author>
<author initials="H." surname="Frystyk" fullname="H. Frystyk">
<organization>MIT Laboratory for Computer Science</organization>
<address><email>frystyk@w3.org</email></address>
</author>
<author initials="L." surname="Masinter" fullname="L. Masinter">
<organization>Xerox Corporation</organization>
<address><email>masinter@parc.xerox.com</email></address>
</author>
<author initials="P." surname="Leach" fullname="P. Leach">
<organization>Microsoft Corporation</organization>
<address><email>paulle@microsoft.com</email></address>
</author>
<author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
<organization>W3C</organization>
<address><email>timbl@w3.org</email></address>
</author>
<date month="June" year="1999"/>
</front>
<seriesInfo name="RFC" value="2616"/>
</reference>
<reference anchor="RFC3629">
<front>
<title>UTF-8, a transformation format of ISO 10646</title>
<author initials="F." surname="Yergeau" fullname="F. Yergeau">
<organization>Alis Technologies</organization>
<address><email>fyergeau@alis.com</email></address>
</author>
<date month="November" year="2003"/>
</front>
<seriesInfo name="RFC" value="3629"/>
<seriesInfo name="STD" value="63"/>
</reference>
<reference anchor="RFC5646">
<front>
<title>Tags for Identifying Languages</title>
<author initials="A." surname="Phillips" fullname="Addison Phillips" role="editor">
<organization>Lab126</organization>
<address><email>addison@inter-locale.com</email></address>
</author>
<author initials="M." surname="Davis" fullname="Mark Davis" role="editor">
<organization>Google</organization>
<address><email>mark.davis@google.com</email></address>
</author>
<date month="September" year="2009"/>
</front>
<seriesInfo name="BCP" value="47"/>
<seriesInfo name="RFC" value="5646"/>
</reference>
<reference anchor="RFC5234">
<front>
<title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
<author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
<organization>Brandenburg InternetWorking</organization>
<address>
<phone>+1.408.246.8253</phone>
<email>dcrocker@bbiw.net</email>
</address>
</author>
<author initials="P." surname="Overell" fullname="Paul Overell">
<organization>THUS plc.</organization>
<address>
<email>paul.overell@thus.net</email>
</address>
</author>
<date month="January" year="2008"/>
</front>
<seriesInfo name="STD" value="68"/>
<seriesInfo name="RFC" value="5234"/>
</reference>
<reference anchor="ISO-8859-1">
<front>
<title>Information technology -- 8-bit single-byte coded graphic character sets -- Part 1: Latin alphabet No. 1</title>
<author>
<organization>International Organization for Standardization</organization>
</author>
<date year="1998"/>
</front>
<seriesInfo name="ISO/IEC" value="8859-1:1998"/>
</reference>
</references>
<references title="Informative References">
<reference anchor="RFC2047">
<front>
<title abbrev="Message Header Extensions">MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text</title>
<author initials="K." surname="Moore" fullname="Keith Moore">
<organization>University of Tennessee</organization>
<address><email>moore@cs.utk.edu</email></address>
</author>
<date month="November" year="1996"/>
</front>
<seriesInfo name="RFC" value="2047"/>
</reference>
<reference anchor="RFC2231">
<front>
<title abbrev="MIME Value and Encoded Word Extensions">MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations</title>
<author initials="N." surname="Freed" fullname="Ned Freed">
<organization abbrev="Innosoft">Innosoft International, Inc.</organization>
<address><email>ned.freed@innosoft.com</email></address>
</author>
<author initials="K." surname="Moore" fullname="Keith Moore">
<organization>University of Tennessee</organization>
<address><email>moore@cs.utk.edu</email></address>
</author>
<date year="1997" month="November"/>
</front>
<seriesInfo name="RFC" value="2231"/>
</reference>
<reference anchor="RFC2277">
<front>
<title abbrev="Charset Policy">IETF Policy on Character Sets and Languages</title>
<author initials="H.T." surname="Alvestrand" fullname="Harald Tveit Alvestrand">
<organization>UNINETT</organization>
<address><email>Harald.T.Alvestrand@uninett.no</email></address>
</author>
<date year="1998" month="January"/>
</front>
<seriesInfo name="BCP" value="18"/>
<seriesInfo name="RFC" value="2277"/>
</reference>
<reference anchor="RFC2388">
<front>
<title abbrev="multipart/form-data">Returning Values from Forms: multipart/form-data</title>
<author initials="L." surname="Masinter" fullname="Larry Masinter">
<organization>Xerox Palo Alto Research Center</organization>
<address>
<email>masinter@parc.xerox.com</email>
</address>
</author>
<date year="1998" month="August"/>
</front>
<seriesInfo name="RFC" value="2388"/>
</reference>
<reference anchor="RFC3986">
<front>
<title abbrev="URI Generic Syntax">Uniform Resource Identifier (URI): Generic Syntax</title>
<author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
<organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
<address>
<email>timbl@w3.org</email>
<uri>http://www.w3.org/People/Berners-Lee/</uri>
</address>
</author>
<author initials="R." surname="Fielding" fullname="Roy T. Fielding">
<organization abbrev="Day Software">Day Software</organization>
<address>
<email>fielding@gbiv.com</email>
<uri>http://roy.gbiv.com/</uri>
</address>
</author>
<author initials="L." surname="Masinter" fullname="Larry Masinter">
<organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
<address>
<email>LMM@acm.org</email>
<uri>http://larry.masinter.net/</uri>
</address>
</author>
<date month="January" year="2005"/>
</front>
<seriesInfo name="RFC" value="3986"/>
<seriesInfo name="STD" value="66"/>
</reference>
<reference anchor="USASCII">
<front>
<title>Coded Character Set -- 7-bit American Standard Code for Information Interchange</title>
<author>
<organization>American National Standards Institute</organization>
</author>
<date year="1986"/>
</front>
<seriesInfo name="ANSI" value="X3.4"/>
</reference>
<reference anchor="RFC2978">
<front>
<title>IANA Charset Registration Procedures</title>
<author initials="N." surname="Freed" fullname="N. Freed"/>
<author initials="J." surname="Postel" fullname="J. Postel"/>
<date year="2000" month="October"/>
</front>
<seriesInfo name="BCP" value="19"/>
<seriesInfo name="RFC" value="2978"/>
</reference>
</references>
<section title="Document History and Future Plans (to be removed by RFC Editor before publication)" anchor="history">
<t>
Problems with the internationalization of the HTTP Content-Disposition header
field have been known for many years (see test cases at
<eref target="http://greenbytes.de/tech/tc2231/"/>).
</t>
<t>
During IETF 72 (<eref target="http://tools.ietf.org/wg/httpbis/minutes?item=minutes72.html"/>),
the HTTPbis Working Group shortly discussed how to deal with the underspecification
of (1) Content-Disposition, and its (2) internationalization aspects.
Back then, there was rough consensus in the room to move the definition
into a separate draft.
</t>
<t>
This specification addresses problem (2), by defining a simple subset of
the encoding format defined in RFC 2231. A separate specification,
draft-reschke-rfc2183-in-http, is planned to address problem (1). Note that
this approach was chosen because Content-Disposition is just an example for
an HTTP header field using this kind of encoding. Another example
is the currently proposed Link header field (draft-nottingham-http-link-header).
</t>
<t>
This document is planned to be published on the IETF Standards Track, so that
other standards-track level documents can depend on it, such as the new
specification of Content-Disposition, or potentially future revisions of
the HTTP Link Header specification.
</t>
<t>
Also note that this document specifies a proper subset of the extensions
defined in RFC 2231, but does not normatively refer to it. Thus, RFC 2231
can be revised separately, should the email community decide to.
</t>
</section>
<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
<section title="Since draft-reschke-rfc2231-in-http-00">
<t>
Use RFC5234-style ABNF, closer to the one used in RFC 2231.
</t>
<t>
Make RFC 2231 dependency informative, so this specification can evolve
independently.
</t>
<t>
Explain the ABNF in prose.
</t>
</section>
<section title="Since draft-reschke-rfc2231-in-http-01">
<t>
Remove unneeded RFC5137 notation (code point vs character).
</t>
</section>
<section title="Since draft-reschke-rfc2231-in-http-02">
<t>
And and resolve issues "charset", "repeats"
and "rfc4646".
</t>
</section>
<section title="Since draft-reschke-rfc2231-in-http-03">
<t>
And and resolve issue "charsetmatch".
</t>
</section>
<section title="Since draft-reschke-rfc2231-in-http-04">
<t>
Add and resolve issues "badseq" and
"tokenquotcharset".
</t>
</section>
<section title="Since draft-reschke-rfc2231-in-http-05">
<t>
Say "header field" instead of "header" in the context of HTTP.
</t>
</section>
<section title="Since draft-reschke-rfc2231-in-http-06">
<t>
Add an appendix discussing document history and future plans, to be removed before publication.
</t>
</section>
<section title="Since draft-reschke-rfc2231-in-http-07">
<t>
Add and resolve issues "<ed:issueref>impl</ed:issueref>" and "<ed:issueref>rel-2388</ed:issueref>".
</t>
</section>
</section>
</back>
</rfc>| PAFTECH AB 2003-2026 | 2026-04-23 19:50:50 |