RFC3066 日本語訳

Network Working Group                                      H. Alvestrand
Request for Comments: 3066                                 Cisco Systems
BCP: 47                                                     January 2001
Obsoletes: 1766
Category: Best Current Practice

Network Working Group H. Alvestrand Request for Comments: 3066 Cisco Systems BCP: 47 January 2001 Obsoletes: 1766 Category: Best Current Practice

                Tags for the Identification of Languages

Tags for the Identification of Languages

Status of this Memo

Status of this Memo

   This document specifies an Internet Best Current Practices for the
   Internet Community, and requests discussion and suggestions for
   improvements.  Distribution of this memo is unlimited.

This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited.

Copyright Notice

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Copyright (C) The Internet Society (2001). All Rights Reserved.

Abstract

Abstract

   This document describes a language tag for use in cases where it is
   desired to indicate the language used in an information object, how
   to register values for use in this language tag, and a construct for
   matching such language tags.

This document describes a language tag for use in cases where it is desired to indicate the language used in an information object, how to register values for use in this language tag, and a construct for matching such language tags.

1. Introduction

1. Introduction

   Human beings on our planet have, past and present, used a number of
   languages.  There are many reasons why one would want to identify the
   language used when presenting information.

Human beings on our planet have, past and present, used a number of languages. There are many reasons why one would want to identify the language used when presenting information.

   In some contexts, it is possible to have information available in
   more than one language, or it might be possible to provide tools
   (such as dictionaries) to assist in the understanding of a language.

In some contexts, it is possible to have information available in more than one language, or it might be possible to provide tools (such as dictionaries) to assist in the understanding of a language.

   Also, many types of information processing require knowledge of the
   language in which information is expressed in order for that process
   to be performed on the information; for example spell-checking,
   computer-synthesized speech, Braille, or high-quality print
   renderings.

Also, many types of information processing require knowledge of the language in which information is expressed in order for that process to be performed on the information; for example spell-checking, computer-synthesized speech, Braille, or high-quality print renderings.

   One means of indicating the language used is by labeling the
   information content with an identifier for the language that is used
   in this information content.

One means of indicating the language used is by labeling the information content with an identifier for the language that is used in this information content.

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   This document specifies an identifier mechanism, a registration
   function for values to be used with that identifier mechanism, and a
   construct for matching against those values.

This document specifies an identifier mechanism, a registration function for values to be used with that identifier mechanism, and a construct for matching against those values.

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC 2119].

The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC 2119].

2. The Language tag

2. The Language tag

2.1 Language tag syntax

2.1 Language tag syntax

   The language tag is composed of one or more parts: A primary language
   subtag and a (possibly empty) series of subsequent subtags.

The language tag is composed of one or more parts: A primary language subtag and a (possibly empty) series of subsequent subtags.

   The syntax of this tag in ABNF [RFC 2234] is:

The syntax of this tag in ABNF [RFC 2234] is:

    Language-Tag = Primary-subtag *( "-" Subtag )

Language-Tag = Primary-subtag *( "-" Subtag )

    Primary-subtag = 1*8ALPHA

Primary-subtag = 1*8ALPHA

    Subtag = 1*8(ALPHA / DIGIT)

Subtag = 1*8(ALPHA / DIGIT)

   The productions ALPHA and DIGIT are imported from RFC 2234; they
   denote respectively the characters A to Z in upper or lower case and
   the digits from 0 to 9.  The character "-" is HYPHEN-MINUS (ABNF:
   %x2D).

The productions ALPHA and DIGIT are imported from RFC 2234; they denote respectively the characters A to Z in upper or lower case and the digits from 0 to 9. The character "-" is HYPHEN-MINUS (ABNF: %x2D).

   All tags are to be treated as case insensitive; there exist
   conventions for capitalization of some of them, but these should not
   be taken to carry meaning.  For instance, [ISO 3166] recommends that
   country codes are capitalized (MN Mongolia), while [ISO 639]
   recommends that language codes are written in lower case (mn
   Mongolian).

All tags are to be treated as case insensitive; there exist conventions for capitalization of some of them, but these should not be taken to carry meaning. For instance, [ISO 3166] recommends that country codes are capitalized (MN Mongolia), while [ISO 639] recommends that language codes are written in lower case (mn Mongolian).

2.2 Language tag sources

2.2 Language tag sources

   The namespace of language tags is administered by the Internet
   Assigned Numbers Authority (IANA) [RFC 2860] according to the rules
   in section 3 of this document.

The namespace of language tags is administered by the Internet Assigned Numbers Authority (IANA) [RFC 2860] according to the rules in section 3 of this document.

   The following rules apply to the primary subtag:

The following rules apply to the primary subtag:

   - All 2-letter subtags are interpreted according to assignments found
     in ISO standard 639, "Code for the representation of names of
     languages" [ISO 639], or assignments subsequently made by the ISO
     639 part 1 maintenance agency or governing standardization bodies.
     (Note: A revision is underway, and is expected to be released as

- All 2-letter subtags are interpreted according to assignments found in ISO standard 639, "Code for the representation of names of languages" [ISO 639], or assignments subsequently made by the ISO 639 part 1 maintenance agency or governing standardization bodies. (Note: A revision is underway, and is expected to be released as

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     ISO 639-1:2000)

ISO 639-1:2000)

   - All 3-letter subtags are interpreted according to assignments found
     in ISO 639 part 2, "Codes for the representation of names of
     languages -- Part 2: Alpha-3 code [ISO 639-2]", or assignments
     subsequently made by the ISO 639 part 2 maintenance agency or
     governing standardization bodies.

- All 3-letter subtags are interpreted according to assignments found in ISO 639 part 2, "Codes for the representation of names of languages -- Part 2: Alpha-3 code [ISO 639-2]", or assignments subsequently made by the ISO 639 part 2 maintenance agency or governing standardization bodies.

   - The value "i" is reserved for IANA-defined registrations

- The value "i" is reserved for IANA-defined registrations

   - The value "x" is reserved for private use.  Subtags of "x" shall
     not be registered by the IANA.

- The value "x" is reserved for private use. Subtags of "x" shall not be registered by the IANA.

   - Other values shall not be assigned except by revision of this
     standard.

- Other values shall not be assigned except by revision of this standard.

   The reason for reserving all other tags is to be open towards new
   revisions of ISO 639; the use of "i" and "x" is the minimum we can do
   here to be able to extend the mechanism to meet our immediate
   requirements.

The reason for reserving all other tags is to be open towards new revisions of ISO 639; the use of "i" and "x" is the minimum we can do here to be able to extend the mechanism to meet our immediate requirements.

   The following rules apply to the second subtag:

The following rules apply to the second subtag:

   - All 2-letter subtags are interpreted as ISO 3166 alpha-2 country
     codes from [ISO 3166], or subsequently assigned by the ISO 3166
     maintenance agency or governing standardization bodies, denoting
     the area to which this language variant relates.

- All 2-letter subtags are interpreted as ISO 3166 alpha-2 country codes from [ISO 3166], or subsequently assigned by the ISO 3166 maintenance agency or governing standardization bodies, denoting the area to which this language variant relates.

   - Tags with second subtags of 3 to 8 letters may be registered with
     IANA, according to the rules in chapter 5 of this document.

- Tags with second subtags of 3 to 8 letters may be registered with IANA, according to the rules in chapter 5 of this document.

   - Tags with 1-letter second subtags may not be assigned except after
     revision of this standard.

- Tags with 1-letter second subtags may not be assigned except after revision of this standard.

   There are no rules apart from the syntactic ones for the third and
   subsequent subtags.

There are no rules apart from the syntactic ones for the third and subsequent subtags.

   Tags constructed wholly from the codes that are assigned
   interpretations by this chapter do not need to be registered with
   IANA before use.

Tags constructed wholly from the codes that are assigned interpretations by this chapter do not need to be registered with IANA before use.

   The information in a subtag may for instance be:

The information in a subtag may for instance be:

   - Country identification, such as en-US (this usage is described in
     ISO 639)

- Country identification, such as en-US (this usage is described in ISO 639)

   - Dialect or variant information, such as en-scouse

- Dialect or variant information, such as en-scouse

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   - Languages not listed in ISO 639 that are not variants of any listed
     language, which can be registered with the i-prefix, such as i-
     tsolyani

- Languages not listed in ISO 639 that are not variants of any listed language, which can be registered with the i-prefix, such as i- tsolyani

   - Region identification, such as sgn-US-MA (Martha's Vineyard Sign
     Language, which is found in the state of Massachusetts, US)

- Region identification, such as sgn-US-MA (Martha's Vineyard Sign Language, which is found in the state of Massachusetts, US)

   This document leaves the decision on what tags are appropriate or not
   to the registration process described in section 3.

This document leaves the decision on what tags are appropriate or not to the registration process described in section 3.

   ISO 639 defines a maintenance agency for additions to and changes in
   the list of languages in ISO 639.  This agency is:

ISO 639 defines a maintenance agency for additions to and changes in the list of languages in ISO 639. This agency is:

        International Information Centre for Terminology (Infoterm)
        P.O. Box 130
        A-1021 Wien
        Austria

International Information Centre for Terminology (Infoterm) P.O. Box 130 A-1021 Wien Austria

        Phone: +43 1 26 75 35 Ext. 312
        Fax:   +43 1 216 32 72

Phone: +43 1 26 75 35 Ext. 312 Fax: +43 1 216 32 72

   ISO 639-2 defines a maintenance agency for additions to and changes
   in the list of languages in ISO 639-2.  This agency is:

ISO 639-2 defines a maintenance agency for additions to and changes in the list of languages in ISO 639-2. This agency is:

        Library of Congress
        Network Development and MARC Standards Office
        Washington, D.C. 20540
        USA

Library of Congress Network Development and MARC Standards Office Washington, D.C. 20540 USA

        Phone: +1 202 707 6237
        Fax:   +1 202 707 0115
        URL: http://www.loc.gov/standards/iso639

Phone: +1 202 707 6237 Fax: +1 202 707 0115 URL: http://www.loc.gov/standards/iso639

   The maintenance agency for ISO 3166 (country codes) is:

The maintenance agency for ISO 3166 (country codes) is:

        ISO 3166 Maintenance Agency Secretariat
        c/o DIN Deutsches Institut fuer Normung
        Burggrafenstrasse 6
        Postfach 1107
        D-10787 Berlin
        Germany

ISO 3166 Maintenance Agency Secretariat c/o DIN Deutsches Institut fuer Normung Burggrafenstrasse 6 Postfach 1107 D-10787 Berlin Germany

        Phone: +49 30 26 01 320
        Fax:   +49 30 26 01 231
        URL: http://www.din.de/gremien/nas/nabd/iso3166ma/

Phone: +49 30 26 01 320 Fax: +49 30 26 01 231 URL: http://www.din.de/gremien/nas/nabd/iso3166ma/

   ISO 3166 reserves the country codes AA, QM-QZ, XA-XZ and ZZ as user-
   assigned codes.  These MUST NOT be used to form language tags.

ISO 3166 reserves the country codes AA, QM-QZ, XA-XZ and ZZ as user- assigned codes. These MUST NOT be used to form language tags.

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2.3 Choice of language tag

2.3 Choice of language tag

   One may occasionally be faced with several possible tags for the same
   body of text.

One may occasionally be faced with several possible tags for the same body of text.

   Interoperability is best served if all users send the same tag, and
   use the same tag for the same language for all documents.  If an
   application has requirements that make the rules here inapplicable,
   the application protocol specification MUST specify how the procedure
   varies from the one given here.

Interoperability is best served if all users send the same tag, and use the same tag for the same language for all documents. If an application has requirements that make the rules here inapplicable, the application protocol specification MUST specify how the procedure varies from the one given here.

   The text below is based on the set of tags known to the tagging
   entity.

The text below is based on the set of tags known to the tagging entity.

   1. Use the most precise tagging known to the sender that can be
      ascertained and is useful within the application context.

1. Use the most precise tagging known to the sender that can be ascertained and is useful within the application context.

   2. When a language has both an ISO 639-1 2-character code and an ISO
      639-2 3-character code, you MUST use the tag derived from the ISO
      639-1 2-character code.

2. When a language has both an ISO 639-1 2-character code and an ISO 639-2 3-character code, you MUST use the tag derived from the ISO 639-1 2-character code.

   3. When a language has no ISO 639-1 2-character code, and the ISO
      639-2/T (Terminology) code and the ISO 639-2/B (Bibliographic)
      code differ, you MUST use the Terminology code.  NOTE: At present,
      all languages for which there is a difference have 2-character
      codes, and the displeasure of developers about the existence of 2
      code sets has been adequately communicated to ISO.  So this
      situation will hopefully not arise.

3. When a language has no ISO 639-1 2-character code, and the ISO 639-2/T (Terminology) code and the ISO 639-2/B (Bibliographic) code differ, you MUST use the Terminology code. NOTE: At present, all languages for which there is a difference have 2-character codes, and the displeasure of developers about the existence of 2 code sets has been adequately communicated to ISO. So this situation will hopefully not arise.

   4. When a language has both an IANA-registered tag (i-something) and
      a tag derived from an ISO registered code, you MUST use the ISO
      tag.  NOTE: When such a situation is discovered, the IANA-
      registered tag SHOULD be deprecated as soon as possible.

4. When a language has both an IANA-registered tag (i-something) and a tag derived from an ISO registered code, you MUST use the ISO tag. NOTE: When such a situation is discovered, the IANA- registered tag SHOULD be deprecated as soon as possible.

   5. You SHOULD NOT use the UND (Undetermined) code unless the protocol
      in use forces you to give a value for the language tag, even if
      the language is unknown.  Omitting the tag is preferred.

5. You SHOULD NOT use the UND (Undetermined) code unless the protocol in use forces you to give a value for the language tag, even if the language is unknown. Omitting the tag is preferred.

   6. You SHOULD NOT use the MUL (Multiple) tag if the protocol allows
      you to use multiple languages, as is the case for the Content-
      Language:  header.

6. You SHOULD NOT use the MUL (Multiple) tag if the protocol allows you to use multiple languages, as is the case for the Content- Language: header.

   NOTE: In order to avoid versioning difficulties in applications such
   as that of RFC 1766, the ISO 639 Registration Authority Joint
   Advisory Committee (RA-JAC) has agreed on the following policy
   statement:

NOTE: In order to avoid versioning difficulties in applications such as that of RFC 1766, the ISO 639 Registration Authority Joint Advisory Committee (RA-JAC) has agreed on the following policy statement:

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     "After the publication of ISO/DIS 639-1 as an International
     Standard, no new 2-letter code shall be added to ISO 639-1 unless a
     3-letter code is also added at the same time to ISO 639-2.  In
     addition, no language with a 3-letter code available at the time of
     publication of ISO 639-1 which at that time had no 2-letter code
     shall be subsequently given a 2-letter code."

"After the publication of ISO/DIS 639-1 as an International Standard, no new 2-letter code shall be added to ISO 639-1 unless a 3-letter code is also added at the same time to ISO 639-2. In addition, no language with a 3-letter code available at the time of publication of ISO 639-1 which at that time had no 2-letter code shall be subsequently given a 2-letter code."

   This will ensure that, for example, a user who implements "hwi"
   (Hawaiian), which currently has no 2-letter code, will not find his
   or her data invalidated by eventual addition of a 2-letter code for
   that language."

This will ensure that, for example, a user who implements "hwi" (Hawaiian), which currently has no 2-letter code, will not find his or her data invalidated by eventual addition of a 2-letter code for that language."

2.4 Meaning of the language tag

2.4 Meaning of the language tag

   The language tag always defines a language as spoken (or written,
   signed or otherwise signaled) by human beings for communication of
   information to other human beings.  Computer languages such as
   programming languages are explicitly excluded.  There is no
   guaranteed relationship between languages whose tags begin with the
   same series of subtags; specifically, they are NOT guaranteed to be
   mutually intelligible, although it will sometimes be the case that
   they are.

The language tag always defines a language as spoken (or written, signed or otherwise signaled) by human beings for communication of information to other human beings. Computer languages such as programming languages are explicitly excluded. There is no guaranteed relationship between languages whose tags begin with the same series of subtags; specifically, they are NOT guaranteed to be mutually intelligible, although it will sometimes be the case that they are.

   The relationship between the tag and the information it relates to is
   defined by the standard describing the context in which it appears.
   Accordingly, this section can only give possible examples of its
   usage.

The relationship between the tag and the information it relates to is defined by the standard describing the context in which it appears. Accordingly, this section can only give possible examples of its usage.

   - For a single information object, it could be taken as the set of
     languages that is required for a complete comprehension of the
     complete object.
     Example: Plain text documents.

- For a single information object, it could be taken as the set of languages that is required for a complete comprehension of the complete object. Example: Plain text documents.

   - For an aggregation of information objects, it should be taken as
     the set of languages used inside components of that aggregation.
     Examples: Document stores and libraries.

- For an aggregation of information objects, it should be taken as the set of languages used inside components of that aggregation. Examples: Document stores and libraries.

   - For information objects whose purpose is to provide alternatives,
     the set of tags associated with it should be regarded as a hint
     that the content is provided in several languages, and that one has
     to inspect each of the alternatives in order to find its language
     or languages.  In this case, a tag with multiple languages does not
     mean that one needs to be multi-lingual to get complete
     understanding of the document.
     Example: MIME multipart/alternative.

- For information objects whose purpose is to provide alternatives, the set of tags associated with it should be regarded as a hint that the content is provided in several languages, and that one has to inspect each of the alternatives in order to find its language or languages. In this case, a tag with multiple languages does not mean that one needs to be multi-lingual to get complete understanding of the document. Example: MIME multipart/alternative.

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   - In markup languages, such as HTML and XML, language information can
     be added to each part of the document identified by the markup
     structure (including the whole document itself).  For example, one
     could write <span lang="FR">C'est la vie.</span> inside a Norwegian
     document; the Norwegian-speaking user could then access a French-
     Norwegian dictionary to find out what the marked section meant.  If
     the user were listening to that document through a speech synthesis
     interface, this formation could be used to signal the synthesizer
     to appropriately apply French text-to-speech pronunciation rules to
     that span of text, instead of misapplying the Norwegian rules.

- In markup languages, such as HTML and XML, language information can be added to each part of the document identified by the markup structure (including the whole document itself). For example, one could write <span lang="FR">C'est la vie.</span> inside a Norwegian document; the Norwegian-speaking user could then access a French- Norwegian dictionary to find out what the marked section meant. If the user were listening to that document through a speech synthesis interface, this formation could be used to signal the synthesizer to appropriately apply French text-to-speech pronunciation rules to that span of text, instead of misapplying the Norwegian rules.

2.5 Language-range

2.5 Language-range

   Since the publication of RFC 1766, it has become apparent that there
   is a need to define a term for a set of languages whose tags all
   begin with the same sequence of subtags.

Since the publication of RFC 1766, it has become apparent that there is a need to define a term for a set of languages whose tags all begin with the same sequence of subtags.

   The following definition of language-range is derived from HTTP/1.1
   [RFC 2616].

The following definition of language-range is derived from HTTP/1.1 [RFC 2616].

             language-range  = language-tag / "*"

language-range = language-tag / "*"

   That is, a language-range has the same syntax as a language-tag, or
   is the single character "*".

That is, a language-range has the same syntax as a language-tag, or is the single character "*".

   A language-range matches a language-tag if it exactly equals the tag,
   or if it exactly equals a prefix of the tag such that the first
   character following the prefix is "-".

A language-range matches a language-tag if it exactly equals the tag, or if it exactly equals a prefix of the tag such that the first character following the prefix is "-".

   The special range "*" matches any tag.  A protocol which uses
   language ranges may specify additional rules about the semantics of
   "*"; for instance, HTTP/1.1 specifies that the range "*" matches only
   languages not matched by any other range within an "Accept-Language:"
   header.

The special range "*" matches any tag. A protocol which uses language ranges may specify additional rules about the semantics of "*"; for instance, HTTP/1.1 specifies that the range "*" matches only languages not matched by any other range within an "Accept-Language:" header.

   NOTE: This use of a prefix matching rule does not imply that language
   tags are assigned to languages in such a way that it is always true
   that if a user understands a language with a certain tag, then this
   user will also understand all languages with tags for which this tag
   is a prefix.  The prefix rule simply allows the use of prefix tags if
   this is the case.

NOTE: This use of a prefix matching rule does not imply that language tags are assigned to languages in such a way that it is always true that if a user understands a language with a certain tag, then this user will also understand all languages with tags for which this tag is a prefix. The prefix rule simply allows the use of prefix tags if this is the case.

3. IANA registration procedure for language tags

3. IANA registration procedure for language tags

   The procedure given here MUST be used by anyone who wants to use a
   language tag not given an interpretation in chapter 2.2 of this
   document or previously registered with IANA.

The procedure given here MUST be used by anyone who wants to use a language tag not given an interpretation in chapter 2.2 of this document or previously registered with IANA.

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   This procedure MAY also be used to register information with the IANA
   about a tag defined by this document, for instance if one wishes to
   make publicly available a reference to the definition for a language
   such as sgn-US (American Sign Language).

This procedure MAY also be used to register information with the IANA about a tag defined by this document, for instance if one wishes to make publicly available a reference to the definition for a language such as sgn-US (American Sign Language).

   Tags with a first subtag of "x" need not, and cannot, be registered.

Tags with a first subtag of "x" need not, and cannot, be registered.

   The process starts by filling out the registration form reproduced
   below.

The process starts by filling out the registration form reproduced below.

   ----------------------------------------------------------------------

----------------------------------------------------------------------

   LANGUAGE TAG REGISTRATION FORM

LANGUAGE TAG REGISTRATION FORM

   Name of requester          :

Name of requester :

   E-mail address of requester:

E-mail address of requester:

   Tag to be registered       :

Tag to be registered :

   English name of language   :

English name of language :

   Native name of language (transcribed into ASCII):

Native name of language (transcribed into ASCII):

   Reference to published description of the language (book or article):

Reference to published description of the language (book or article):

   Any other relevant information:

Any other relevant information:

   ----------------------------------------------------------------------

----------------------------------------------------------------------

   The language form must be sent to <ietf-languages@iana.org> for a 2-
   week review period before it can be submitted to IANA.  (This is an
   open list.  Requests to be added should be sent to <ietf-languages-
   request@iana.org>.)

The language form must be sent to <ietf-languages@iana.org> for a 2- week review period before it can be submitted to IANA. (This is an open list. Requests to be added should be sent to <ietf-languages- request@iana.org>.)

   When the two week period has passed, the language tag reviewer, who
   is appointed by the IETF Applications Area Director, either forwards
   the request to IANA@IANA.ORG, or rejects it because of significant
   objections raised on the list.  Note that the reviewer can raise
   objections on the list himself, if he so desires.  The important
   thing is that the objection must be made publicly.

When the two week period has passed, the language tag reviewer, who is appointed by the IETF Applications Area Director, either forwards the request to IANA@IANA.ORG, or rejects it because of significant objections raised on the list. Note that the reviewer can raise objections on the list himself, if he so desires. The important thing is that the objection must be made publicly.

   The applicant is free to modify a rejected application with
   additional information and submit it again; this restarts the 2-week
   comment period.

The applicant is free to modify a rejected application with additional information and submit it again; this restarts the 2-week comment period.

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   Decisions made by the reviewer may be appealed to the IESG [RFC 2028]
   under the same rules as other IETF decisions [RFC 2026].  All
   registered forms are available online in the directory
   http://www.iana.org/numbers.html under "languages".

Decisions made by the reviewer may be appealed to the IESG [RFC 2028] under the same rules as other IETF decisions [RFC 2026]. All registered forms are available online in the directory http://www.iana.org/numbers.html under "languages".

   Updates of registrations follow the same procedure as registrations.
   The language tag reviewer decides whether to allow a new registrant
   to update a registration made by someone else; in the normal case,
   objections by the original registrant would carry extra weight in
   such a decision.

Updates of registrations follow the same procedure as registrations. The language tag reviewer decides whether to allow a new registrant to update a registration made by someone else; in the normal case, objections by the original registrant would carry extra weight in such a decision.

   There is no deletion of registrations; when some registered tag
   should not be used any more, for instance because a corresponding ISO
   639 code has been registered, the registration should be amended by
   adding a remark like "DEPRECATED: use <new code> instead" to the
   "other relevant information" section.

There is no deletion of registrations; when some registered tag should not be used any more, for instance because a corresponding ISO 639 code has been registered, the registration should be amended by adding a remark like "DEPRECATED: use <new code> instead" to the "other relevant information" section.

   Note: The purpose of the "published description" is intended as an
   aid to people trying to verify whether a language is registered, or
   what language a particular tag refers to.  In most cases, reference
   to an authoritative grammar or dictionary of the language will be
   useful; in cases where no such work exists, other well known works
   describing that language or in that language may be appropriate.  The
   language tag reviewer decides what constitutes a "good enough"
   reference material.

Note: The purpose of the "published description" is intended as an aid to people trying to verify whether a language is registered, or what language a particular tag refers to. In most cases, reference to an authoritative grammar or dictionary of the language will be useful; in cases where no such work exists, other well known works describing that language or in that language may be appropriate. The language tag reviewer decides what constitutes a "good enough" reference material.

4. Security Considerations

4. Security Considerations

   The only security issue that has been raised with language tags since
   the publication of RFC 1766, which stated that "Security issues are
   believed to be irrelevant to this memo", is a concern with language
   ranges used in content negotiation - that they may be used to infer
   the nationality of the sender, and thus identify potential targets
   for surveillance.

The only security issue that has been raised with language tags since the publication of RFC 1766, which stated that "Security issues are believed to be irrelevant to this memo", is a concern with language ranges used in content negotiation - that they may be used to infer the nationality of the sender, and thus identify potential targets for surveillance.

   This is a special case of the general problem that anything you send
   is visible to the receiving party; it is useful to be aware that such
   concerns can exist in some cases.

This is a special case of the general problem that anything you send is visible to the receiving party; it is useful to be aware that such concerns can exist in some cases.

   The evaluation of the exact magnitude of the threat, and any possible
   countermeasures, is left to each application protocol.

The evaluation of the exact magnitude of the threat, and any possible countermeasures, is left to each application protocol.

5. Character set considerations

5. Character set considerations

   Language tags may always be presented using the characters A-Z, a-z,
   0-9 and HYPHEN-MINUS, which are present in most character sets, so
   presentation of language tags should not have any character set
   issues.

Language tags may always be presented using the characters A-Z, a-z, 0-9 and HYPHEN-MINUS, which are present in most character sets, so presentation of language tags should not have any character set issues.

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   The issue of deciding upon the rendering of a character set based on
   the language tag is not addressed in this memo; however, it is
   thought impossible to make such a decision correctly for all cases
   unless means of switching language in the middle of a text are
   defined (for example, a rendering engine that decides font based on
   Japanese or Chinese language may produce suboptimal output when a
   mixed Japanese-Chinese text is encountered)

The issue of deciding upon the rendering of a character set based on the language tag is not addressed in this memo; however, it is thought impossible to make such a decision correctly for all cases unless means of switching language in the middle of a text are defined (for example, a rendering engine that decides font based on Japanese or Chinese language may produce suboptimal output when a mixed Japanese-Chinese text is encountered)

6. Acknowledgements

6. Acknowledgements

   This document has benefited from many rounds of review and comments
   in various fora of the IETF and the Internet working groups.

This document has benefited from many rounds of review and comments in various fora of the IETF and the Internet working groups.

   Any list of contributors is bound to be incomplete; please regard the
   following as only a selection from the group of people who have
   contributed to make this document what it is today.

Any list of contributors is bound to be incomplete; please regard the following as only a selection from the group of people who have contributed to make this document what it is today.

   In alphabetical order:

In alphabetical order:

   Glenn Adams, Tim Berners-Lee, Marc Blanchet, Nathaniel Borenstein,
   Eric Brunner, Sean M. Burke, John Clews, Jim Conklin, Peter
   Constable, John Cowan, Mark Crispin, Dave Crocker, Mark Davis, Martin
   Duerst, Michael Everson, Ned Freed, Tim Goodwin, Dirk-Willem van
   Gulik, Marion Gunn, Paul Hoffman, Olle Jarnefors, Kent Karlsson, John
   Klensin, Alain LaBonte, Chris Newman, Keith Moore, Masataka Ohta,
   Keld Jorn Simonsen, Otto Stolz, Rhys Weatherley, Misha Wolf, Francois
   Yergeau and many, many others.

Glenn Adams, Tim Berners-Lee, Marc Blanchet, Nathaniel Borenstein, Eric Brunner, Sean M. Burke, John Clews, Jim Conklin, Peter Constable, John Cowan, Mark Crispin, Dave Crocker, Mark Davis, Martin Duerst, Michael Everson, Ned Freed, Tim Goodwin, Dirk-Willem van Gulik, Marion Gunn, Paul Hoffman, Olle Jarnefors, Kent Karlsson, John Klensin, Alain LaBonte, Chris Newman, Keith Moore, Masataka Ohta, Keld Jorn Simonsen, Otto Stolz, Rhys Weatherley, Misha Wolf, Francois Yergeau and many, many others.

   Special thanks must go to Michael Everson, who has served as language
   tag reviewer for almost the complete period since the publication of
   RFC 1766, and has provided a great deal of input to this revision.

Special thanks must go to Michael Everson, who has served as language tag reviewer for almost the complete period since the publication of RFC 1766, and has provided a great deal of input to this revision.

7. Author's Address

7. Author's Address

   Harald Tveit Alvestrand
   Cisco Systems
   Weidemanns vei 27
   7043 Trondheim
   NORWAY

Harald Tveit Alvestrand Cisco Systems Weidemanns vei 27 7043 Trondheim NORWAY

   Phone: +47 73 50 33 52
   EMail: Harald@Alvestrand.no

Phone: +47 73 50 33 52 EMail: Harald@Alvestrand.no

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8. References

8. References

   [ISO 639]   ISO 639:1988 (E/F) - Code for the representation of names
               of languages - The International Organization for
               Standardization, 1st edition, 1988-04-01 Prepared by
               ISO/TC 37 - Terminology (principles and coordination).
               Note that a new version (ISO 639-1:2000) is in
               preparation at the time of this writing.

[ISO 639] ISO 639:1988 (E/F) - Code for the representation of names of languages - The International Organization for Standardization, 1st edition, 1988-04-01 Prepared by ISO/TC 37 - Terminology (principles and coordination). Note that a new version (ISO 639-1:2000) is in preparation at the time of this writing.

   [ISO 639-2] ISO 639-2:1998 - Codes for the representation of names of
               languages -- Part 2: Alpha-3 code  - edition 1, 1998-11-
               01, 66 pages, prepared by a Joint Working Group of ISO
               TC46/SC4 and ISO TC37/SC2.

[ISO 639-2] ISO 639-2:1998 - Codes for the representation of names of languages -- Part 2: Alpha-3 code - edition 1, 1998-11- 01, 66 pages, prepared by a Joint Working Group of ISO TC46/SC4 and ISO TC37/SC2.

   [ISO 3166]  ISO 3166:1988 (E/F) - Codes for the representation of
               names of countries - The International Organization for
               Standardization, 3rd edition, 1988-08-15.

[ISO 3166] ISO 3166:1988 (E/F) - Codes for the representation of names of countries - The International Organization for Standardization, 3rd edition, 1988-08-15.

   [RFC 1327]  Kille, S., "Mapping between X.400 (1988) / ISO 10021 and
               RFC 822", RFC 1327, May 1992.

[RFC 1327] Kille, S., "Mapping between X.400 (1988) / ISO 10021 and RFC 822", RFC 1327, May 1992.

   [RFC 1521]  Borenstein, N., and N. Freed, "MIME Part One: Mechanisms
               for Specifying and Describing the Format of Internet
               Message Bodies", RFC 1521, September 1993.

[RFC 1521] Borenstein, N., and N. Freed, "MIME Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies", RFC 1521, September 1993.

   [RFC 2026]  Bradner, S., "The Internet Standards Process -- Revision
               3", BCP 9, RFC 2026, October 1996.

[RFC 2026] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996.

   [RFC 2028]  Hovey, R. and S. Bradner, "The Organizations Involved in
               the IETF Standards Process", BCP 11, RFC 2028, October
               1996.

[RFC 2028] Hovey, R. and S. Bradner, "The Organizations Involved in the IETF Standards Process", BCP 11, RFC 2028, October 1996.

   [RFC 2119]  Bradner, S."Key words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC 2119] Bradner, S."Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC 2234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
               Specifications: ABNF", RFC 2234, November 1997.

[RFC 2234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997.

   [RFC 2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
               Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
               Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

[RFC 2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC 2860]  Carpenter, B., Baker, F. and M. Roberts, "Memorandum of
               Understanding Concerning the Technical Work of the
               Internet Assigned Numbers Authority", RFC 2860, June
               2000.

[RFC 2860] Carpenter, B., Baker, F. and M. Roberts, "Memorandum of Understanding Concerning the Technical Work of the Internet Assigned Numbers Authority", RFC 2860, June 2000.

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Appendix A: Language Tag Reference Material

Appendix A: Language Tag Reference Material

   The Library of Congress, maintainers of ISO 639-2, has made the list
   of languages registered available on the Internet.

The Library of Congress, maintainers of ISO 639-2, has made the list of languages registered available on the Internet.

   At the time of this writing, it can be found at
   http://www.loc.gov/standards/iso639-2/langhome.html

At the time of this writing, it can be found at http://www.loc.gov/standards/iso639-2/langhome.html

   The IANA registration forms for registered language codes can be
   found at http://www.iana.org/numbers.html under "languages".

The IANA registration forms for registered language codes can be found at http://www.iana.org/numbers.html under "languages".

   The ISO 3166 Maintenance Agency has published Web pages at

The ISO 3166 Maintenance Agency has published Web pages at

   http://www.din.de/gremien/nas/nabd/iso3166ma/

http://www.din.de/gremien/nas/nabd/iso3166ma/

Appendix B: Changes from RFC 1766

Appendix B: Changes from RFC 1766

   - Email list address changed from ietf-types@uninett.no to ietf-
     languages@iana.org

- Email list address changed from ietf-types@uninett.no to ietf- languages@iana.org

   - Updated author's address

- Updated author's address

   - Added language-range construct from HTTP/1.1

- Added language-range construct from HTTP/1.1

   - Added use of ISO 639-2 language codes

- Added use of ISO 639-2 language codes

   - Added reference to Library of Congress lists of language codes

- Added reference to Library of Congress lists of language codes

   - Changed examples to use registered tags

- Changed examples to use registered tags

   - Added "Any other information" to registration form

- Added "Any other information" to registration form

   - Added description of procedure for updating registrations

- Added description of procedure for updating registrations

   - Changed target category for document from standards track to BCP

- 標準化過程からBCPまでのドキュメントのための変えられた目標カテゴリ

   - Moved the content-language header definition into another document

- 満足している言語ヘッダー定義を別のドキュメントに動かします。

   - Added numbers to the permitted characters in language tags

- 言語タグの受入れられたキャラクタへの加えられた数

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Full Copyright Statement

完全な著作権宣言文

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Copyright(C)インターネット協会(2001)。 All rights reserved。

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

それに関するこのドキュメントと翻訳は、コピーして、それが批評するか、またはそうでなければわかる他のもの、および派生している作品に提供するか、または準備されているかもしれなくて、コピーされて、発行されて、全体か一部広げられた実現を助けるかもしれません、どんな種類の制限なしでも、上の版権情報とこのパラグラフがそのようなすべてのコピーと派生している作品の上に含まれていれば。 しかしながら、このドキュメント自体は何らかの方法で変更されないかもしれません、インターネット協会か他のインターネット組織の版権情報か参照を取り除くのなどように、それを英語以外の言語に翻訳するのが著作権のための手順がインターネットStandardsの過程で定義したどのケースに従わなければならないか、必要に応じてさもなければ、インターネット標準を開発する目的に必要であるのを除いて。

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

上に承諾された限られた許容は、永久であり、インターネット協会、後継者または案配によって取り消されないでしょう。

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

このドキュメントとそして、「そのままで」という基礎とインターネットの振興発展を目的とする組織に、インターネット・エンジニアリング・タスク・フォースが速達の、または、暗示しているすべての保証を放棄するかどうかというここにことであり、他を含んでいて、含まれて、情報の使用がここに侵害しないどんな保証も少しもまっすぐになるという情報か市場性か特定目的への適合性のどんな黙示的な保証。

Acknowledgement

承認

   Funding for the RFC Editor function is currently provided by the
   Internet Society.

RFC Editor機能のための基金は現在、インターネット協会によって提供されます。

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