draft-ietf-httpbis-rfc5987bis-01.txt   draft-ietf-httpbis-rfc5987bis-02.txt 
HTTP Working Group J. Reschke HTTP Working Group J. Reschke
Internet-Draft greenbytes Internet-Draft greenbytes
Obsoletes: 5987 (if approved) March 4, 2016 Obsoletes: 5987 (if approved) July 8, 2016
Intended status: Standards Track Intended status: Standards Track
Expires: September 5, 2016 Expires: January 9, 2017
Indicating Character Encoding and Language for HTTP Header Field Indicating Character Encoding and Language for HTTP Header Field
Parameters Parameters
draft-ietf-httpbis-rfc5987bis-01 draft-ietf-httpbis-rfc5987bis-02
Abstract Abstract
By default, message header field parameters in Hypertext Transfer By default, header field values in Hypertext Transfer Protocol (HTTP)
Protocol (HTTP) messages cannot carry characters outside the ISO- messages cannot directly carry characters outside the US-ASCII coded
8859-1 character set. RFC 2231 defines an encoding mechanism for use character set. RFC 2231 defines an encoding mechanism for use in
in Multipurpose Internet Mail Extensions (MIME) headers. This Multipurpose Internet Mail Extensions (MIME) headers. This document
document specifies an encoding suitable for use in HTTP header fields specifies an encoding suitable for use in HTTP header fields that is
that is compatible with a profile of the encoding defined in RFC compatible with a profile of the encoding defined in RFC 2231.
2231.
Editorial Note (To be removed by RFC Editor before publication) Editorial Note (To be removed by RFC Editor before publication)
Discussion of this draft takes place on the HTTPBIS working group Discussion of this draft takes place on the HTTPBIS working group
mailing list (ietf-http-wg@w3.org), which is archived at mailing list (ietf-http-wg@w3.org), which is archived at
<https://lists.w3.org/Archives/Public/ietf-http-wg/>. <https://lists.w3.org/Archives/Public/ietf-http-wg/>.
Working Group information can be found at <http://httpwg.github.io/>; Working Group information can be found at <http://httpwg.github.io/>;
source code and issues list for this draft can be found at source code and issues list for this draft can be found at
<https://github.com/httpwg/http-extensions>. <https://github.com/httpwg/http-extensions>.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 5, 2016.
This Internet-Draft will expire on January 9, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 4 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 4
3. Comparison to RFC 2231 and Definition of the Encoding . . . . 4 3. Comparison to RFC 2231 and Definition of the Encoding . . . . 4
3.1. Parameter Continuations . . . . . . . . . . . . . . . . . 5 3.1. Parameter Continuations . . . . . . . . . . . . . . . . . 5
3.2. Parameter Value Character Encoding and Language 3.2. Parameter Value Character Encoding and Language
Information . . . . . . . . . . . . . . . . . . . . . . . 5 Information . . . . . . . . . . . . . . . . . . . . . . . 5
3.2.1. Definition . . . . . . . . . . . . . . . . . . . . . . 5 3.2.1. Definition . . . . . . . . . . . . . . . . . . . . . . 5
3.2.2. Historical Notes . . . . . . . . . . . . . . . . . . . 7 3.2.2. Historical Notes . . . . . . . . . . . . . . . . . . . 7
3.2.3. Examples . . . . . . . . . . . . . . . . . . . . . . . 8 3.2.3. Examples . . . . . . . . . . . . . . . . . . . . . . . 7
3.3. Language Specification in Encoded Words . . . . . . . . . 8 3.3. Language Specification in Encoded Words . . . . . . . . . 8
4. Guidelines for Usage in HTTP Header Field Definitions . . . . 9 4. Guidelines for Usage in HTTP Header Field Definitions . . . . 8
4.1. When to Use the Extension . . . . . . . . . . . . . . . . 9 4.1. When to Use the Extension . . . . . . . . . . . . . . . . 9
4.2. Error Handling . . . . . . . . . . . . . . . . . . . . . . 9 4.2. Error Handling . . . . . . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References . . . . . . . . . . . . . . . . . . . 10
7.2. Informative References . . . . . . . . . . . . . . . . . . 12 7.2. Informative References . . . . . . . . . . . . . . . . . . 11
Appendix A. Changes from RFC 5987 . . . . . . . . . . . . . . . . 13 Appendix A. Changes from RFC 5987 . . . . . . . . . . . . . . . . 13
Appendix B. Implementation Report . . . . . . . . . . . . . . . . 13 Appendix B. Implementation Report . . . . . . . . . . . . . . . . 13
Appendix C. Change Log (to be removed by RFC Editor before Appendix C. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 14 publication) . . . . . . . . . . . . . . . . . . . . 14
C.1. Since RFC5987 . . . . . . . . . . . . . . . . . . . . . . 14 C.1. Since RFC5987 . . . . . . . . . . . . . . . . . . . . . . 14
C.2. Since draft-reschke-rfc5987bis-00 . . . . . . . . . . . . 14 C.2. Since draft-reschke-rfc5987bis-00 . . . . . . . . . . . . 14
C.3. Since draft-reschke-rfc5987bis-01 . . . . . . . . . . . . 14 C.3. Since draft-reschke-rfc5987bis-01 . . . . . . . . . . . . 14
C.4. Since draft-reschke-rfc5987bis-02 . . . . . . . . . . . . 14 C.4. Since draft-reschke-rfc5987bis-02 . . . . . . . . . . . . 14
C.5. Since draft-reschke-rfc5987bis-03 . . . . . . . . . . . . 14 C.5. Since draft-reschke-rfc5987bis-03 . . . . . . . . . . . . 14
C.6. Since draft-reschke-rfc5987bis-04 . . . . . . . . . . . . 14 C.6. Since draft-reschke-rfc5987bis-04 . . . . . . . . . . . . 14
C.7. Since draft-reschke-rfc5987bis-05 . . . . . . . . . . . . 14 C.7. Since draft-reschke-rfc5987bis-05 . . . . . . . . . . . . 14
C.8. Since draft-reschke-rfc5987bis-06 . . . . . . . . . . . . 14 C.8. Since draft-reschke-rfc5987bis-06 . . . . . . . . . . . . 14
C.9. Since draft-ietf-httpbis-rfc5987bis-00 . . . . . . . . . . 14 C.9. Since draft-ietf-httpbis-rfc5987bis-00 . . . . . . . . . . 14
C.10. Since draft-ietf-httpbis-rfc5987bis-01 . . . . . . . . . . 15
Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 15 Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
By default, message header field parameters in HTTP ([RFC2616]) By default, header field values in HTTP messages ([RFC7230]) cannot
messages cannot carry characters outside the ISO-8859-1 coded directly carry characters outside the US-ASCII coded character set
character set ([ISO-8859-1]). RFC 2231 ([RFC2231]) defines an ([RFC0020]). RFC 2231 ([RFC2231]) defines an encoding mechanism for
encoding mechanism for use in MIME headers. This document specifies use in MIME headers. This document specifies an encoding suitable
an encoding suitable for use in HTTP header fields that is compatible for use in HTTP header fields that is compatible with a profile of
with a profile of the encoding defined in RFC 2231. the encoding defined in RFC 2231.
This document obsoletes [RFC5987] and moves it to "historic" status; This document obsoletes [RFC5987] and moves it to "historic" status;
the changes are summarized in Appendix A. the changes are summarized in Appendix A.
Note: in the remainder of this document, RFC 2231 is only Note: in the remainder of this document, RFC 2231 is only
referenced for the purpose of explaining the choice of features referenced for the purpose of explaining the choice of features
that were adopted; they are therefore purely informative. that were adopted; they are therefore purely informative.
Note: this encoding does not apply to message payloads transmitted Note: this encoding does not apply to message payloads transmitted
over HTTP, such as when using the media type "multipart/form-data" over HTTP, such as when using the media type "multipart/form-data"
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encoding, making it hard for senders to decide which encoding to use. encoding, making it hard for senders to decide which encoding to use.
Thus, recipients implementing this specification MUST support the Thus, recipients implementing this specification MUST support the
"UTF-8" character encoding [RFC3629]. "UTF-8" character encoding [RFC3629].
Furthermore, RFC 2231 allows the character encoding information to be Furthermore, RFC 2231 allows the character encoding information to be
left out. The encoding defined by this specification does not allow left out. The encoding defined by this specification does not allow
that. that.
3.2.1. Definition 3.2.1. Definition
The syntax for parameters is defined in Section 3.6 of [RFC2616] The presence of extended parameter values usually is indicated by a
(with RFC 2616 implied LWS translated to RFC 5234 LWSP): parameter name ending in an asterisk character. Note however that
this is just a convention, and that it needs to be explicitly
parameter = attribute LWSP "=" LWSP value specified in the definition of the header field using this extension
(see Section 4).
attribute = token
value = token / quoted-string
quoted-string = <quoted-string, see [RFC7230], Section 3.2.6>
token = <token, see [RFC7230], Section 3.2.6>
In order to include character encoding and language information, this
specification modifies the RFC 2616 grammar to be:
parameter = reg-parameter / ext-parameter
reg-parameter = parmname LWSP "=" LWSP value
ext-parameter = parmname "*" LWSP "=" LWSP ext-value
parmname = 1*attr-char The ABNF for extended parameter values is specified below:
ext-value = charset "'" [ language ] "'" value-chars ext-value = charset "'" [ language ] "'" value-chars
; like RFC 2231's <extended-initial-value> ; like RFC 2231's <extended-initial-value>
; (see [RFC2231], Section 7) ; (see [RFC2231], Section 7)
charset = "UTF-8" / mime-charset charset = "UTF-8" / mime-charset
mime-charset = 1*mime-charsetc mime-charset = 1*mime-charsetc
mime-charsetc = ALPHA / DIGIT mime-charsetc = ALPHA / DIGIT
/ "!" / "#" / "$" / "%" / "&" / "!" / "#" / "$" / "%" / "&"
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value-chars = *( pct-encoded / attr-char ) value-chars = *( pct-encoded / attr-char )
pct-encoded = "%" HEXDIG HEXDIG pct-encoded = "%" HEXDIG HEXDIG
; see [RFC3986], Section 2.1 ; see [RFC3986], Section 2.1
attr-char = ALPHA / DIGIT attr-char = ALPHA / DIGIT
/ "!" / "#" / "$" / "&" / "+" / "-" / "." / "!" / "#" / "$" / "&" / "+" / "-" / "."
/ "^" / "_" / "`" / "|" / "~" / "^" / "_" / "`" / "|" / "~"
; token except ( "*" / "'" / "%" ) ; token except ( "*" / "'" / "%" )
Thus, a parameter is either a regular parameter (reg-parameter), as The value part of an extended parameter (ext-value) is a token that
previously defined in Section 3.6 of [RFC2616], or an extended consists of three parts:
parameter (ext-parameter).
Extended parameters are those where the left-hand side of the 1. the REQUIRED character encoding name (charset),
assignment ends with an asterisk character.
The value part of an extended parameter (ext-value) is a token that 2. the OPTIONAL language information (language), and
consists of three parts: the REQUIRED character encoding name
(charset), the OPTIONAL language information (language), and a 3. a character sequence representing the actual value (value-chars),
character sequence representing the actual value (value-chars), separated by single quote characters.
separated by single quote characters. Note that both character
encoding names and language tags are restricted to the US-ASCII coded Note that both character encoding names and language tags are
character set, and are matched case-insensitively (see [RFC2978], restricted to the US-ASCII coded character set, and are matched case-
Section 2.3 and [RFC5646], Section 2.1.1). insensitively (see [RFC2978], Section 2.3 and [RFC5646], Section
2.1.1).
Inside the value part, characters not contained in attr-char are Inside the value part, characters not contained in attr-char are
encoded into an octet sequence using the specified character encoded into an octet sequence using the specified character
encoding. That octet sequence is then percent-encoded as specified encoding. That octet sequence is then percent-encoded as specified
in Section 2.1 of [RFC3986]. in Section 2.1 of [RFC3986].
Producers MUST use the "UTF-8" ([RFC3629]) character encoding. Producers MUST use the "UTF-8" ([RFC3629]) character encoding.
Extension character encodings (mime-charset) are reserved for future Extension character encodings (mime-charset) are reserved for future
use. use.
Note: recipients should be prepared to handle encoding errors, Note: recipients should be prepared to handle encoding errors,
such as malformed or incomplete percent escape sequences, or non- such as malformed or incomplete percent escape sequences, or non-
decodable octet sequences, in a robust manner. This specification decodable octet sequences, in a robust manner. This specification
does not mandate any specific behavior, for instance, the does not mandate any specific behavior, for instance, the
following strategies are all acceptable: following strategies are all acceptable:
* ignoring the parameter, * ignoring the parameter,
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encoding names using that character have been registered at the time encoding names using that character have been registered at the time
of this writing. of this writing.
For backwards compatibility with RFC 2231, the encoding defined by For backwards compatibility with RFC 2231, the encoding defined by
this specification deviates from common parameter syntax in that the this specification deviates from common parameter syntax in that the
quoted-string notation is not allowed. Implementations using generic quoted-string notation is not allowed. Implementations using generic
parser components might not be able to detect the use of quoted- parser components might not be able to detect the use of quoted-
string notation and thus might accept that format, although invalid, string notation and thus might accept that format, although invalid,
as well. as well.
[RFC5987] did require support for ISO-8859-1, too; for compatibility [RFC5987] did require support for ISO-8859-1 ([ISO-8859-1]), too; for
with legacy code, recipients are encouraged to support this encoding compatibility with legacy code, recipients are encouraged to support
as well. this encoding as well.
3.2.3. Examples 3.2.3. Examples
Non-extended notation, using "token": Non-extended notation, using "token":
foo: bar; title=Economy foo: bar; title=Economy
Non-extended notation, using "quoted-string": Non-extended notation, using "quoted-string":
foo: bar; title="US-$ rates" foo: bar; title="US-$ rates"
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specification has deprecated use of the encoding forms defined in RFC specification has deprecated use of the encoding forms defined in RFC
2047 (see Section 3.2.4 of [RFC7230]). 2047 (see Section 3.2.4 of [RFC7230]).
Thus, this specification does not include this feature. Thus, this specification does not include this feature.
4. Guidelines for Usage in HTTP Header Field Definitions 4. Guidelines for Usage in HTTP Header Field Definitions
Specifications of HTTP header fields that use the extensions defined Specifications of HTTP header fields that use the extensions defined
in Section 3.2 ought to clearly state that. A simple way to achieve in Section 3.2 ought to clearly state that. A simple way to achieve
this is to normatively reference this specification, and to include this is to normatively reference this specification, and to include
the ext-value production into the ABNF for that header field. the ext-value production into the ABNF for specific header field
parameters.
For instance: For instance:
foo-header = "foo" LWSP ":" LWSP token ";" LWSP title-param foo = token ";" LWSP title-param
title-param = "title" LWSP "=" LWSP value title-param = "title" LWSP "=" LWSP value
/ "title*" LWSP "=" LWSP ext-value / "title*" LWSP "=" LWSP ext-value
ext-value = <see RFC 5987, Section 3.2> ext-value = <see draft-ietf-httpbis-rfc5987bis, Section 3.2>
[[pub: Upon publication as RFC, the string
"draft-ietf-httpbis-rfc5987bis" needs to be replaced with the RFC
name, and this comment needs to be removed.]]
Note: The Parameter Value Continuation feature defined in Section Note: The Parameter Value Continuation feature defined in Section
3 of [RFC2231] makes it impossible to have multiple instances of 3 of [RFC2231] makes it impossible to have multiple instances of
extended parameters with identical parmname components, as the extended parameters with identical parmname components, as the
processing of continuations would become ambiguous. Thus, processing of continuations would become ambiguous. Thus,
specifications using this extension are advised to disallow this specifications using this extension are advised to disallow this
case for compatibility with RFC 2231. case for compatibility with RFC 2231.
Note: This specification does not automatically assign a new Note: This specification does not automatically assign a new
interpretration to parameter names ending in an asterisk. As interpretration to parameter names ending in an asterisk. As
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4.1. When to Use the Extension 4.1. When to Use the Extension
Section 4.2 of [RFC2277] requires that protocol elements containing Section 4.2 of [RFC2277] requires that protocol elements containing
human-readable text are able to carry language information. Thus, human-readable text are able to carry language information. Thus,
the ext-value production ought to be always used when the parameter the ext-value production ought to be always used when the parameter
value is of textual nature and its language is known. value is of textual nature and its language is known.
Furthermore, the extension ought to also be used whenever the Furthermore, the extension ought to also be used whenever the
parameter value needs to carry characters not present in the US-ASCII parameter value needs to carry characters not present in the US-ASCII
([USASCII]) coded character set (note that it would be unacceptable ([RFC0020]) coded character set (note that it would be unacceptable
to define a new parameter that would be restricted to a subset of the to define a new parameter that would be restricted to a subset of the
Unicode character set). Unicode character set).
4.2. Error Handling 4.2. Error Handling
Header field specifications need to define whether multiple instances Header field specifications need to define whether multiple instances
of parameters with identical parmname components are allowed, and how of parameters with identical parmname components are allowed, and how
they should be processed. This specification suggests that a they should be processed. This specification suggests that a
parameter using the extended syntax takes precedence. This would parameter using the extended syntax takes precedence. This would
allow producers to use both formats without breaking recipients that allow producers to use both formats without breaking recipients that
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specified. specified.
6. IANA Considerations 6. IANA Considerations
There are no IANA Considerations related to this specification. There are no IANA Considerations related to this specification.
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC0020] Cerf, V., "ASCII format for network interchange",
STD 80, RFC 20, DOI 10.17487/RFC0020, October 1969,
<http://www.rfc-editor.org/info/rfc20>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997, RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, DOI 10.17487/
RFC2616, June 1999,
<http://www.rfc-editor.org/info/rfc2616>.
[RFC2978] Freed, N. and J. Postel, "IANA Charset Registration [RFC2978] Freed, N. and J. Postel, "IANA Charset Registration
Procedures", BCP 19, RFC 2978, DOI 10.17487/RFC2978, Procedures", BCP 19, RFC 2978, DOI 10.17487/RFC2978,
October 2000, <http://www.rfc-editor.org/info/rfc2978>. October 2000, <http://www.rfc-editor.org/info/rfc2978>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629,
November 2003, November 2003,
<http://www.rfc-editor.org/info/rfc3629>. <http://www.rfc-editor.org/info/rfc3629>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter,
skipping to change at page 11, line 47 skipping to change at page 11, line 42
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Message Syntax and Transfer Protocol (HTTP/1.1): Message Syntax and
Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>. <http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Semantics and Content", Transfer Protocol (HTTP/1.1): Semantics and Content",
RFC 7231, DOI 10.17487/RFC7231, June 2014, RFC 7231, DOI 10.17487/RFC7231, June 2014,
<http://www.rfc-editor.org/info/rfc7231>. <http://www.rfc-editor.org/info/rfc7231>.
[USASCII] American National Standards Institute, "Coded Character
Set -- 7-bit American Standard Code for Information
Interchange", ANSI X3.4, 1986.
7.2. Informative References 7.2. Informative References
[Err1912] RFC Errata, "Errata ID 1912, RFC 2978", [Err1912] RFC Errata, "Errata ID 1912, RFC 2978", October 2009,
<http://www.rfc-editor.org>. <http://www.rfc-editor.org>.
[ISO-8859-1] International Organization for Standardization, [ISO-8859-1] International Organization for Standardization,
"Information technology -- 8-bit single-byte coded "Information technology -- 8-bit single-byte coded
graphic character sets -- Part 1: Latin alphabet No. graphic character sets -- Part 1: Latin alphabet No.
1", ISO/IEC 8859-1:1998, 1998. 1", ISO/IEC 8859-1:1998, 1998.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet
Mail Extensions (MIME) Part One: Format of Internet Mail Extensions (MIME) Part One: Format of Internet
Message Bodies", RFC 2045, DOI 10.17487/RFC2045, Message Bodies", RFC 2045, DOI 10.17487/RFC2045,
skipping to change at page 12, line 41 skipping to change at page 12, line 31
<http://www.rfc-editor.org/info/rfc2231>. <http://www.rfc-editor.org/info/rfc2231>.
[RFC2277] Alvestrand, H., "IETF Policy on Character Sets and [RFC2277] Alvestrand, H., "IETF Policy on Character Sets and
Languages", BCP 18, RFC 2277, DOI 10.17487/RFC2277, Languages", BCP 18, RFC 2277, DOI 10.17487/RFC2277,
January 1998, <http://www.rfc-editor.org/info/rfc2277>. January 1998, <http://www.rfc-editor.org/info/rfc2277>.
[RFC2388] Masinter, L., "Returning Values from Forms: multipart/ [RFC2388] Masinter, L., "Returning Values from Forms: multipart/
form-data", RFC 2388, DOI 10.17487/RFC2388, form-data", RFC 2388, DOI 10.17487/RFC2388,
August 1998, <http://www.rfc-editor.org/info/rfc2388>. August 1998, <http://www.rfc-editor.org/info/rfc2388>.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, DOI 10.17487/
RFC2616, June 1999,
<http://www.rfc-editor.org/info/rfc2616>.
[RFC5987] Reschke, J., "Character Set and Language Encoding for [RFC5987] Reschke, J., "Character Set and Language Encoding for
Hypertext Transfer Protocol (HTTP) Header Field Hypertext Transfer Protocol (HTTP) Header Field
Parameters", RFC 5987, DOI 10.17487/RFC5987, Parameters", RFC 5987, DOI 10.17487/RFC5987,
August 2010, <http://www.rfc-editor.org/info/rfc5987>. August 2010, <http://www.rfc-editor.org/info/rfc5987>.
[RFC5988] Nottingham, M., "Web Linking", RFC 5988, DOI 10.17487/ [RFC5988] Nottingham, M., "Web Linking", RFC 5988, DOI 10.17487/
RFC5988, October 2010, RFC5988, October 2010,
<http://www.rfc-editor.org/info/rfc5988>. <http://www.rfc-editor.org/info/rfc5988>.
[RFC6266] Reschke, J., "Use of the Content-Disposition Header [RFC6266] Reschke, J., "Use of the Content-Disposition Header
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Appendix A. Changes from RFC 5987 Appendix A. Changes from RFC 5987
This section summarizes the changes compared to [RFC5987]: This section summarizes the changes compared to [RFC5987]:
o The document title was changed to "Indicating Character Encoding o The document title was changed to "Indicating Character Encoding
and Language for HTTP Header Field Parameters". and Language for HTTP Header Field Parameters".
o The requirement to support the "ISO-8859-1" encoding was removed. o The requirement to support the "ISO-8859-1" encoding was removed.
o The document does not attempt to re-define a generic "parameter"
ABNF anymore (it turned out that there really isn't a generic
definition of parameters in HTTP; for instance, there are subtle
differences with respect to whitespace handling).
Appendix B. Implementation Report Appendix B. Implementation Report
The encoding defined in this document currently is used for two The encoding defined in this document currently is used for two
different HTTP header fields: different HTTP header fields:
o "Content-Disposition", defined in [RFC6266], and o "Content-Disposition", defined in [RFC6266], and
o "Link", defined in [RFC5988]. o "Link", defined in [RFC5988].
As the encoding is a profile/clarification of the one defined in As the encoding is a profile/clarification of the one defined in
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Update status with respect to Safari 6. Update status with respect to Safari 6.
Started work on update with respect to RFC 723x. Started work on update with respect to RFC 723x.
C.9. Since draft-ietf-httpbis-rfc5987bis-00 C.9. Since draft-ietf-httpbis-rfc5987bis-00
Editorial changes; introducing non-ASCII characters into author's Editorial changes; introducing non-ASCII characters into author's
address, acknowledgements, and examples. address, acknowledgements, and examples.
C.10. Since draft-ietf-httpbis-rfc5987bis-01
Removed mention of RFC 2616 from Abstract and Introduction.
Reference RFC 20 for US-ASCII.
Do not attempt to define a generic parameter ABNF; just concentrate
on the parameter value syntax.
Appendix D. Acknowledgements Appendix D. Acknowledgements
Thanks to Martin Dürst and Frank Ellermann for help figuring out Thanks to Martin Dürst and Frank Ellermann for help figuring out
ABNF details, to Graham Klyne and Alexey Melnikov for general review, ABNF details, to Graham Klyne and Alexey Melnikov for general review,
to Chris Newman for pointing out an RFC 2231 incompatibility, and to to Chris Newman for pointing out an RFC 2231 incompatibility, and to
Benjamin Carlyle, Roar Lauritzsen, Eric Lawrence, and James Manger Benjamin Carlyle, Roar Lauritzsen, Eric Lawrence, and James Manger
for implementer's feedback. for implementer's feedback.
Author's Address Author's Address
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