draft-ietf-ltru-registry-14.txt   rfc4646.txt 
Network Working Group A. Phillips, Ed. Network Working Group A. Phillips, Ed.
Internet-Draft Quest Software Request for Comments: 4646 Yahoo! Inc.
Obsoletes: 3066 (if approved) M. Davis, Ed. BCP: 47 M. Davis, Ed.
Expires: April 17, 2006 IBM Obsoletes: 3066 Google
October 14, 2005 Category: Best Current Practice September 2006
Tags for Identifying Languages Tags for Identifying Languages
draft-ietf-ltru-registry-14
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at Status of This Memo
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 17, 2006. 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 (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
This document describes the structure, content, construction, and This document describes the structure, content, construction, and
semantics of language tags for use in cases where it is desirable to semantics of language tags for use in cases where it is desirable to
indicate the language used in an information object. It also indicate the language used in an information object. It also
describes how to register values for use in language tags and the describes how to register values for use in language tags and the
creation of user defined extensions for private interchange. creation of user-defined extensions for private interchange. This
document, in combination with RFC 4647, replaces RFC 3066, which
replaced RFC 1766.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................3
2. The Language Tag . . . . . . . . . . . . . . . . . . . . . . . 4 2. The Language Tag ................................................4
2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Syntax .....................................................4
2.2. Language Subtag Sources and Interpretation . . . . . . . . 6 2.2. Language Subtag Sources and Interpretation .................7
2.2.1. Primary Language Subtag . . . . . . . . . . . . . . . 8 2.2.1. Primary Language Subtag .............................8
2.2.2. Extended Language Subtags . . . . . . . . . . . . . . 10 2.2.2. Extended Language Subtags ..........................10
2.2.3. Script Subtag . . . . . . . . . . . . . . . . . . . . 10 2.2.3. Script Subtag ......................................11
2.2.4. Region Subtag . . . . . . . . . . . . . . . . . . . . 11 2.2.4. Region Subtag ......................................11
2.2.5. Variant Subtags . . . . . . . . . . . . . . . . . . . 13 2.2.5. Variant Subtags ....................................13
2.2.6. Extension Subtags . . . . . . . . . . . . . . . . . . 14 2.2.6. Extension Subtags ..................................14
2.2.7. Private Use Subtags . . . . . . . . . . . . . . . . . 15 2.2.7. Private Use Subtags ................................16
2.2.8. Pre-Existing RFC 3066 Registrations . . . . . . . . . 16 2.2.8. Preexisting RFC 3066 Registrations .................16
2.2.9. Classes of Conformance . . . . . . . . . . . . . . . . 16 2.2.9. Classes of Conformance .............................17
3. Registry Format and Maintenance . . . . . . . . . . . . . . . 18 3. Registry Format and Maintenance ................................18
3.1. Format of the IANA Language Subtag Registry . . . . . . . 18 3.1. Format of the IANA Language Subtag Registry ...............18
3.2. Language Subtag Reviewer . . . . . . . . . . . . . . . . . 23 3.2. Language Subtag Reviewer ..................................24
3.3. Maintenance of the Registry . . . . . . . . . . . . . . . 24 3.3. Maintenance of the Registry ...............................24
3.4. Stability of IANA Registry Entries . . . . . . . . . . . . 25 3.4. Stability of IANA Registry Entries ........................25
3.5. Registration Procedure for Subtags . . . . . . . . . . . . 28 3.5. Registration Procedure for Subtags ........................29
3.6. Possibilities for Registration . . . . . . . . . . . . . . 31 3.6. Possibilities for Registration ............................32
3.7. Extensions and Extensions Registry . . . . . . . . . . . . 33 3.7. Extensions and Extensions Registry ........................34
3.8. Initialization of the Registries . . . . . . . . . . . . . 36 3.8. Initialization of the Registries ..........................37
4. Formation and Processing of Language Tags . . . . . . . . . . 38 4. Formation and Processing of Language Tags ......................38
4.1. Choice of Language Tag . . . . . . . . . . . . . . . . . . 38 4.1. Choice of Language Tag ....................................38
4.2. Meaning of the Language Tag . . . . . . . . . . . . . . . 40 4.2. Meaning of the Language Tag ...............................40
4.3. Length Considerations . . . . . . . . . . . . . . . . . . 41 4.3. Length Considerations .....................................41
4.3.1. Working with Limited Buffer Sizes . . . . . . . . . . 41 4.3.1. Working with Limited Buffer Sizes ..................42
4.3.2. Truncation of Language Tags . . . . . . . . . . . . . 43 4.3.2. Truncation of Language Tags ........................43
4.4. Canonicalization of Language Tags . . . . . . . . . . . . 43 4.4. Canonicalization of Language Tags .........................44
4.5. Considerations for Private Use Subtags . . . . . . . . . . 45 4.5. Considerations for Private Use Subtags ....................45
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47 5. IANA Considerations ............................................46
5.1. Language Subtag Registry . . . . . . . . . . . . . . . . . 47 5.1. Language Subtag Registry ..................................46
5.2. Extensions Registry . . . . . . . . . . . . . . . . . . . 48 5.2. Extensions Registry .......................................47
6. Security Considerations . . . . . . . . . . . . . . . . . . . 49 6. Security Considerations ........................................48
7. Character Set Considerations . . . . . . . . . . . . . . . . . 50 7. Character Set Considerations ...................................48
8. Changes from RFC 3066 . . . . . . . . . . . . . . . . . . . . 51 8. Changes from RFC 3066 ..........................................49
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 54 9. References .....................................................52
9.1. Normative References . . . . . . . . . . . . . . . . . . . 54 9.1. Normative References ......................................52
9.2. Informative References . . . . . . . . . . . . . . . . . . 55 9.2. Informative References ....................................53
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 57 Appendix A. Acknowledgements ......................................55
Appendix B. Examples of Language Tags (Informative) . . . . . . . 58 Appendix B. Examples of Language Tags (Informative) ...............56
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 61
Intellectual Property and Copyright Statements . . . . . . . . . . 62
1. Introduction 1. Introduction
Human beings on our planet have, past and present, used a number of 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 languages. There are many reasons why one would want to identify the
language used when presenting or requesting information. language used when presenting or requesting information.
A user's language preferences often need to be identified so that A user's language preferences often need to be identified so that
appropriate processing can be applied. For example, the user's appropriate processing can be applied. For example, the user's
language preferences in a Web browser can be used to select Web pages language preferences in a Web browser can be used to select Web pages
appropriately. Language preferences can also be used to select among appropriately. Language preferences can also be used to select among
tools (such as dictionaries) to assist in the processing or tools (such as dictionaries) to assist in the processing or
understanding of content in different languages. understanding of content in different languages.
In addition, knowledge about the particular language used by some In addition, knowledge about the particular language used by some
piece of information content might be useful or even required by some piece of information content might be useful or even required by some
types of processing; for example spell-checking, computer-synthesized types of processing; for example, spell-checking, computer-
speech, Braille transcription, or high-quality print renderings. synthesized speech, Braille transcription, or high-quality print
renderings.
One means of indicating the language used is by labeling the One means of indicating the language used is by labeling the
information content with an identifier or "tag". These tags can be information content with an identifier or "tag". These tags can be
used to specify user preferences when selecting information content, used to specify user preferences when selecting information content,
or for labeling additional attributes of content and associated or for labeling additional attributes of content and associated
resources. resources.
Tags can also be used to indicate additional language attributes of Tags can also be used to indicate additional language attributes of
content. For example, indicating specific information about the content. For example, indicating specific information about the
dialect, writing system, or orthography used in a document or dialect, writing system, or orthography used in a document or
resource may enable the user to obtain information in a form that resource may enable the user to obtain information in a form that
they can understand, or important in processing or rendering the they can understand, or it can be important in processing or
given content into an appropriate form or style. rendering the given content into an appropriate form or style.
This document specifies a particular identifier mechanism (the This document specifies a particular identifier mechanism (the
language tag) and a registration function for values to be used to language tag) and a registration function for values to be used to
form tags. It also defines a mechanism for private use values and form tags. It also defines a mechanism for private use values and
future extension. future extension.
This document replaces [RFC3066], which replaced [RFC1766]. For a This document, in combination with [RFC4647], replaces [RFC3066],
list of changes in this document, see Section 8. which replaced [RFC1766]. For a list of changes in this document,
see Section 8.
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. The Language Tag 2. The Language Tag
Language tags are used to help identify languages, whether spoken, Language tags are used to help identify languages, whether spoken,
written, signed, or otherwise signaled, for the purpose of written, signed, or otherwise signaled, for the purpose of
communication. This includes constructed and artificial languages, communication. This includes constructed and artificial languages,
but excludes languages not intended primarily for human but excludes languages not intended primarily for human
communication, such as programming languages. communication, such as programming languages.
2.1. Syntax 2.1. Syntax
The language tag is composed of one or more parts or "subtags". Each The language tag is composed of one or more parts, known as
subtag consists of a sequence of alpha-numeric characters. Subtags "subtags". Each subtag consists of a sequence of alphanumeric
are distinguished and separated from one another by a hyphen ("-", characters. Subtags are distinguished and separated from one another
ABNF [RFC4234] %x2D). A language tag consists of a "primary by a hyphen ("-", ABNF [RFC4234] %x2D). A language tag consists of a
language" subtag and a (possibly empty) series of subsequent subtags, "primary language" subtag and a (possibly empty) series of subsequent
each of which refines or narrows the range of language identified by subtags, each of which refines or narrows the range of languages
the overall tag. identified by the overall tag.
Usually, each type of subtag is distinguished by length, position in Usually, each type of subtag is distinguished by length, position in
the tag, and content: subtags can be recognized solely by these the tag, and content: subtags can be recognized solely by these
features. The only exception to this is a fixed list of features. The only exception to this is a fixed list of
grandfathered tags registered under RFC 3066 [RFC3066]. This makes grandfathered tags registered under RFC 3066 [RFC3066]. This makes
it possible to construct a parser that can extract and assign some it possible to construct a parser that can extract and assign some
semantic information to the subtags, even if the specific subtag semantic information to the subtags, even if the specific subtag
values are not recognized. Thus a parser need not have an up-to-date values are not recognized. Thus, a parser need not have an up-to-
copy (or any copy at all) of the subtag registry to perform most date copy (or any copy at all) of the subtag registry to perform most
searching and matching operations. searching and matching operations.
The syntax of the language tag in ABNF [RFC4234] is: The syntax of the language tag in ABNF [RFC4234] is:
Language-Tag = langtag Language-Tag = langtag
/ privateuse ; private use tag / privateuse ; private use tag
/ grandfathered ; grandfathered registrations / grandfathered ; grandfathered registrations
langtag = (language langtag = (language
["-" script] ["-" script]
skipping to change at page 6, line 10 skipping to change at page 6, line 10
Note: There is a subtlety in the ABNF for 'variant': variants Note: There is a subtlety in the ABNF for 'variant': variants
starting with a digit MAY be four characters long, while those starting with a digit MAY be four characters long, while those
starting with a letter MUST be at least five characters long. starting with a letter MUST be at least five characters long.
All subtags have a maximum length of eight characters and whitespace All subtags have a maximum length of eight characters and whitespace
is not permitted in a language tag. For examples of language tags, is not permitted in a language tag. For examples of language tags,
see Appendix B. see Appendix B.
Note that although [RFC4234] refers to octets, the language tags Note that although [RFC4234] refers to octets, the language tags
described in this document are sequences of characters from the US- described in this document are sequences of characters from the
ASCII [ISO646] repertoire. Language tags MAY be used in documents US-ASCII [ISO646] repertoire. Language tags MAY be used in documents
and applications that use other encodings, so long as these encompass and applications that use other encodings, so long as these encompass
the US-ASCII repertoire. An example of this would be an XML document the US-ASCII repertoire. An example of this would be an XML document
that uses the UTF-16LE [RFC2781] encoding of [Unicode]. that uses the UTF-16LE [RFC2781] encoding of [Unicode].
The tags and their subtags, including private use and extensions, are The tags and their subtags, including private use and extensions, are
to be treated as case insensitive: there exist conventions for the to be treated as case insensitive: there exist conventions for the
capitalization of some of the subtags, but these MUST NOT be taken to capitalization of some of the subtags, but these MUST NOT be taken to
carry meaning. carry meaning.
For example: For example:
skipping to change at page 6, line 35 skipping to change at page 6, line 35
o [ISO3166-1] recommends that country codes be capitalized ('MN' o [ISO3166-1] recommends that country codes be capitalized ('MN'
Mongolia). Mongolia).
o [ISO15924] recommends that script codes use lower case with the o [ISO15924] recommends that script codes use lower case with the
initial letter capitalized ('Cyrl' Cyrillic). initial letter capitalized ('Cyrl' Cyrillic).
However, in the tags defined by this document, the uppercase US-ASCII However, in the tags defined by this document, the uppercase US-ASCII
letters in the range 'A' through 'Z' are considered equivalent and letters in the range 'A' through 'Z' are considered equivalent and
mapped directly to their US-ASCII lowercase equivalents in the range mapped directly to their US-ASCII lowercase equivalents in the range
'a' through 'z'. Thus the tag "mn-Cyrl-MN" is not distinct from "MN- 'a' through 'z'. Thus, the tag "mn-Cyrl-MN" is not distinct from
cYRL-mn" or "mN-cYrL-Mn" (or any other combination) and each of these "MN-cYRL-mn" or "mN-cYrL-Mn" (or any other combination), and each of
variations conveys the same meaning: Mongolian written in the these variations conveys the same meaning: Mongolian written in the
Cyrillic script as used in Mongolia. Cyrillic script as used in Mongolia.
Although case distinctions do not carry meaning in language tags, Although case distinctions do not carry meaning in language tags,
consistent formatting and presentation of the tags will aid users. consistent formatting and presentation of the tags will aid users.
The format of the tags and subtags in the registry is RECOMMENDED. The format of the tags and subtags in the registry is RECOMMENDED.
In this format, all non-initial two-letter subtags are uppercase, all In this format, all non-initial two-letter subtags are uppercase, all
non-initial four-letter subtags are titlecase, and all other subtags non-initial four-letter subtags are titlecase, and all other subtags
are lowercase. are lowercase.
2.2. Language Subtag Sources and Interpretation 2.2. Language Subtag Sources and Interpretation
skipping to change at page 7, line 18 skipping to change at page 7, line 25
o Tag or tags refers to a complete language tag, such as o Tag or tags refers to a complete language tag, such as
"fr-Latn-CA". Examples of tags in this document are enclosed in "fr-Latn-CA". Examples of tags in this document are enclosed in
double-quotes ("en-US"). double-quotes ("en-US").
o Subtag refers to a specific section of a tag, delimited by hyphen, o Subtag refers to a specific section of a tag, delimited by hyphen,
such as the subtag 'Latn' in "fr-Latn-CA". Examples of subtags in such as the subtag 'Latn' in "fr-Latn-CA". Examples of subtags in
this document are enclosed in single quotes ('Latn'). this document are enclosed in single quotes ('Latn').
o Code or codes refers to values defined in external standards (and o Code or codes refers to values defined in external standards (and
which are used as subtags in this document). For example, 'Latn' that are used as subtags in this document). For example, 'Latn'
is an [ISO15924] script code which was used to define the 'Latn' is an [ISO15924] script code that was used to define the 'Latn'
script subtag for use in a language tag. Examples of codes in script subtag for use in a language tag. Examples of codes in
this document are enclosed in single quotes ('en', 'Latn'). this document are enclosed in single quotes ('en', 'Latn').
The definitions in this section apply to the various subtags within The definitions in this section apply to the various subtags within
the language tags defined by this document, excepting those the language tags defined by this document, excepting those
"grandfathered" tags defined in Section 2.2.8. "grandfathered" tags defined in Section 2.2.8.
Language tags are designed so that each subtag type has unique length Language tags are designed so that each subtag type has unique length
and content restrictions. These make identification of the subtag's and content restrictions. These make identification of the subtag's
type possible, even if the content of the subtag itself is type possible, even if the content of the subtag itself is
skipping to change at page 7, line 44 skipping to change at page 7, line 51
Subtags in the IANA registry that do not come from an underlying Subtags in the IANA registry that do not come from an underlying
standard can only appear in specific positions in a tag. standard can only appear in specific positions in a tag.
Specifically, they can only occur as primary language subtags or as Specifically, they can only occur as primary language subtags or as
variant subtags. variant subtags.
Note that sequences of private use and extension subtags MUST occur Note that sequences of private use and extension subtags MUST occur
at the end of the sequence of subtags and MUST NOT be interspersed at the end of the sequence of subtags and MUST NOT be interspersed
with subtags defined elsewhere in this document. with subtags defined elsewhere in this document.
Single letter and digit subtags are reserved for current or future Single-letter and single-digit subtags are reserved for current or
use. These include the following current uses: future use. These include the following current uses:
o The single letter subtag 'x' is reserved to introduce a sequence o The single-letter subtag 'x' is reserved to introduce a sequence
of private use subtags. The interpretation of any private use of private use subtags. The interpretation of any private use
subtags is defined solely by private agreement and is not defined subtags is defined solely by private agreement and is not defined
by the rules in this section or in any standard or registry by the rules in this section or in any standard or registry
defined in this document. defined in this document.
o All other single letter subtags are reserved to introduce o All other single-letter subtags are reserved to introduce
standardized extension subtag sequences as described in standardized extension subtag sequences as described in
Section 3.7. Section 3.7.
The single letter subtag 'i' is used by some grandfathered tags, such The single-letter subtag 'i' is used by some grandfathered tags, such
as "i-enochian", where it always appears in the first position and as "i-enochian", where it always appears in the first position and
cannot be confused with an extension. cannot be confused with an extension.
2.2.1. Primary Language Subtag 2.2.1. Primary Language Subtag
The primary language subtag is the first subtag in a language tag The primary language subtag is the first subtag in a language tag
(with the exception of private use and certain grandfathered tags) (with the exception of private use and certain grandfathered tags)
and cannot be omitted. The following rules apply to the primary and cannot be omitted. The following rules apply to the primary
language subtag: language subtag:
1. All two character language subtags were defined in the IANA 1. All two-character language subtags were defined in the IANA
registry according to the assignments found in the standard ISO registry according to the assignments found in the standard ISO
639 Part 1, "ISO 639-1:2002, Codes for the representation of 639 Part 1, "ISO 639-1:2002, Codes for the representation of
names of languages -- Part 1: Alpha-2 code" [ISO639-1], or using names of languages -- Part 1: Alpha-2 code" [ISO639-1], or using
assignments subsequently made by the ISO 639 Part 1 maintenance assignments subsequently made by the ISO 639 Part 1 maintenance
agency or governing standardization bodies. agency or governing standardization bodies.
2. All three character language subtags were defined in the IANA 2. All three-character language subtags were defined in the IANA
registry according to the assignments found in ISO 639 Part 2, registry according to the assignments found in ISO 639 Part 2,
"ISO 639-2:1998 - Codes for the representation of names of "ISO 639-2:1998 - Codes for the representation of names of
languages -- Part 2: Alpha-3 code - edition 1" [ISO639-2], or languages -- Part 2: Alpha-3 code - edition 1" [ISO639-2], or
assignments subsequently made by the ISO 639 Part 2 maintenance assignments subsequently made by the ISO 639 Part 2 maintenance
agency or governing standardization bodies. agency or governing standardization bodies.
3. The subtags in the range 'qaa' through 'qtz' are reserved for 3. The subtags in the range 'qaa' through 'qtz' are reserved for
private use in language tags. These subtags correspond to codes private use in language tags. These subtags correspond to codes
reserved by ISO 639-2 for private use. These codes MAY be used reserved by ISO 639-2 for private use. These codes MAY be used
for non-registered primary-language subtags (instead of using for non-registered primary language subtags (instead of using
private use subtags following 'x-'). Please refer to Section 4.5 private use subtags following 'x-'). Please refer to Section 4.5
for more information on private use subtags. for more information on private use subtags.
4. All four character language subtags are reserved for possible 4. All four-character language subtags are reserved for possible
future standardization. future standardization.
5. All language subtags of 5 to 8 characters in length in the IANA 5. All language subtags of 5 to 8 characters in length in the IANA
registry were defined via the registration process in Section 3.5 registry were defined via the registration process in Section 3.5
and MAY be used to form the primary language subtag. At the time and MAY be used to form the primary language subtag. At the time
this document was created, there were no examples of this kind of this document was created, there were no examples of this kind of
subtag and future registrations of this type will be discouraged: subtag and future registrations of this type will be discouraged:
primary languages are strongly RECOMMENDED for registration with primary languages are strongly RECOMMENDED for registration with
ISO 639 and proposals rejected by ISO 639/RA will be closely ISO 639, and proposals rejected by ISO 639/RA will be closely
scrutinized before they are registered with IANA. scrutinized before they are registered with IANA.
6. The single character subtag 'x' as the primary subtag indicates 6. The single-character subtag 'x' as the primary subtag indicates
that the language tag consists solely of subtags whose meaning is that the language tag consists solely of subtags whose meaning is
defined by private agreement. For example, in the tag "x-fr-CH", defined by private agreement. For example, in the tag "x-fr-CH",
the subtags 'fr' and 'CH' SHOULD NOT be taken to represent the the subtags 'fr' and 'CH' SHOULD NOT be taken to represent the
French language or the country of Switzerland (or any other value French language or the country of Switzerland (or any other value
in the IANA registry) unless there is a private agreement in in the IANA registry) unless there is a private agreement in
place to do so. See Section 4.5. place to do so. See Section 4.5.
7. The single character subtag 'i' is used by some grandfathered 7. The single-character subtag 'i' is used by some grandfathered
tags (see Section 2.2.8) such as "i-klingon" and "i-bnn". (Other tags (see Section 2.2.8) such as "i-klingon" and "i-bnn". (Other
grandfathered tags have a primary language subtag in their first grandfathered tags have a primary language subtag in their first
position) position.)
8. Other values MUST NOT be assigned to the primary subtag except by 8. Other values MUST NOT be assigned to the primary subtag except by
revision or update of this document. revision or update of this document.
Note: For languages that have both an ISO 639-1 two character code Note: For languages that have both an ISO 639-1 two-character code
and an ISO 639-2 three character code, only the ISO 639-1 two and an ISO 639-2 three-character code, only the ISO 639-1 two-
character code is defined in the IANA registry. character code is defined in the IANA registry.
Note: For languages that have no ISO 639-1 two character code and for Note: For languages that have no ISO 639-1 two-character code and for
which the ISO 639-2/T (Terminology) code and the ISO 639-2/B which the ISO 639-2/T (Terminology) code and the ISO 639-2/B
(Bibliographic) codes differ, only the Terminology code is defined in (Bibliographic) codes differ, only the Terminology code is defined in
the IANA registry. At the time this document was created, all the IANA registry. At the time this document was created, all
languages that had both kinds of three character code were also languages that had both kinds of three-character code were also
assigned a two character code; it is not expected that future assigned a two-character code; it is not expected that future
assignments of this nature will occur. assignments of this nature will occur.
Note: To avoid problems with versioning and subtag choice as Note: To avoid problems with versioning and subtag choice as
experienced during the transition between RFC 1766 and RFC 3066, as experienced during the transition between RFC 1766 and RFC 3066, as
well as the canonical nature of subtags defined by this document, the well as the canonical nature of subtags defined by this document, the
ISO 639 Registration Authority Joint Advisory Committee (ISO 639/ ISO 639 Registration Authority Joint Advisory Committee (ISO 639/
RA-JAC) has included the following statement in [iso639.principles]: RA-JAC) has included the following statement in [iso639.prin]:
"A language code already in ISO 639-2 at the point of freezing ISO "A language code already in ISO 639-2 at the point of freezing ISO
639-1 shall not later be added to ISO 639-1. This is to ensure 639-1 shall not later be added to ISO 639-1. This is to ensure
consistency in usage over time, since users are directed in Internet consistency in usage over time, since users are directed in Internet
applications to employ the alpha-3 code when an alpha-2 code for that applications to employ the alpha-3 code when an alpha-2 code for that
language is not available." language is not available."
In order to avoid instability in the canonical form of tags, if a
In order to avoid instability in the canonical form of tags, if a two two-character code is added to ISO 639-1 for a language for which a
character code is added to ISO 639-1 for a language for which a three three-character code was already included in ISO 639-2, the two-
character code was already included in ISO 639-2, the two character character code MUST NOT be registered. See Section 3.4.
code MUST NOT be registered. See Section 3.4.
For example, if some content were tagged with 'haw' (Hawaiian), which For example, if some content were tagged with 'haw' (Hawaiian), which
currently has no two character code, the tag would not be invalidated currently has no two-character code, the tag would not be invalidated
if ISO 639-1 were to assign a two character code to the Hawaiian if ISO 639-1 were to assign a two-character code to the Hawaiian
language at a later date. language at a later date.
For example, one of the grandfathered IANA registrations is For example, one of the grandfathered IANA registrations is
"i-enochian". The subtag 'enochian' could be registered in the IANA "i-enochian". The subtag 'enochian' could be registered in the IANA
registry as a primary language subtag (assuming that ISO 639 does not registry as a primary language subtag (assuming that ISO 639 does not
register this language first), making tags such as "enochian-AQ" and register this language first), making tags such as "enochian-AQ" and
"enochian-Latn" valid. "enochian-Latn" valid.
2.2.2. Extended Language Subtags 2.2.2. Extended Language Subtags
The following rules apply to the extended language subtags: The following rules apply to the extended language subtags:
1. Three letter subtags immediately following the primary subtag are 1. Three-letter subtags immediately following the primary subtag are
reserved for future standardization, anticipating work that is reserved for future standardization, anticipating work that is
currently under way on ISO 639. currently under way on ISO 639.
2. Extended language subtags MUST follow the primary subtag and 2. Extended language subtags MUST follow the primary subtag and
precede any other subtags. precede any other subtags.
3. There MAY be up to three extended language subtags. 3. There MAY be up to three extended language subtags.
4. Extended language subtags MUST NOT be registered or used to form 4. Extended language subtags MUST NOT be registered or used to form
language tags. Their syntax is described here so that language tags. Their syntax is described here so that
implementations can be compatible with any future revision of implementations can be compatible with any future revision of
this document which does provide for their registration. this document that does provide for their registration.
Extended language subtag records, once they appear in the registry, Extended language subtag records, once they appear in the registry,
MUST include exactly one 'Prefix' field indicating an appropriate MUST include exactly one 'Prefix' field indicating an appropriate
language subtag or sequence of subtags that MUST always appear as a language subtag or sequence of subtags that MUST always appear as a
prefix to the extended language subtag. prefix to the extended language subtag.
Example: In a future revision or update of this document, the tag Example: In a future revision or update of this document, the tag
"zh-gan" (registered under RFC 3066) might become a valid non- "zh-gan" (registered under RFC 3066) might become a valid non-
grandfathered (that is, redundant) tag in which the subtag 'gan' grandfathered (that is, redundant) tag in which the subtag 'gan'
might represent the Chinese dialect 'Gan'. might represent the Chinese dialect 'Gan'.
2.2.3. Script Subtag 2.2.3. Script Subtag
Script subtags are used to indicate the script or writing system Script subtags are used to indicate the script or writing system
variations that distinguish the written forms of a language or its variations that distinguish the written forms of a language or its
dialects. The following rules apply to the script subtags: dialects. The following rules apply to the script subtags:
1. All four character subtags were defined according to 1. All four-character subtags were defined according to
[ISO15924]--"Codes for the representation of the names of [ISO15924]--"Codes for the representation of names of scripts":
scripts": alpha-4 script codes, or subsequently assigned by the alpha-4 script codes, or subsequently assigned by the ISO 15924
ISO 15924 maintenance agency or governing standardization bodies, maintenance agency or governing standardization bodies, denoting
denoting the script or writing system used in conjunction with the script or writing system used in conjunction with this
this language. language.
2. Script subtags MUST immediately follow the primary language 2. Script subtags MUST immediately follow the primary language
subtag and all extended language subtags and MUST occur before subtag and all extended language subtags and MUST occur before
any other type of subtag described below. any other type of subtag described below.
3. The script subtags 'Qaaa' through 'Qabx' are reserved for private 3. The script subtags 'Qaaa' through 'Qabx' are reserved for private
use in language tags. These subtags correspond to codes reserved use in language tags. These subtags correspond to codes reserved
by ISO 15924 for private use. These codes MAY be used for non- by ISO 15924 for private use. These codes MAY be used for non-
registered script values. Please refer to Section 4.5 for more registered script values. Please refer to Section 4.5 for more
information on private use subtags. information on private use subtags.
4. Script subtags MUST NOT be registered using the process in 4. Script subtags MUST NOT be registered using the process in
Section 3.5 of this document. Variant subtags MAY be considered Section 3.5 of this document. Variant subtags MAY be considered
for registration for that purpose. for registration for that purpose.
5. There MUST be at most one script subtag in a language tag and the 5. There MUST be at most one script subtag in a language tag, and
script subtag SHOULD be omitted when it adds no distinguishing the script subtag SHOULD be omitted when it adds no
value to the tag or when the primary language subtag's record distinguishing value to the tag or when the primary language
includes a Suppress-Script field listing the applicable script subtag's record includes a Suppress-Script field listing the
subtag. applicable script subtag.
Example: "sr-Latn" represents Serbian written using the Latin script. Example: "sr-Latn" represents Serbian written using the Latin script.
2.2.4. Region Subtag 2.2.4. Region Subtag
Region subtags are used to indicate linguistic variations associated Region subtags are used to indicate linguistic variations associated
with or appropriate to a specific country, territory, or region. with or appropriate to a specific country, territory, or region.
Typically, a region subtag is used to indicate regional dialects or Typically, a region subtag is used to indicate regional dialects or
usage, or region-specific spelling conventions. A region subtag can usage, or region-specific spelling conventions. A region subtag can
also be used to indicate that content is expressed in a way that is also be used to indicate that content is expressed in a way that is
appropriate for use throughout a region; for instance, Spanish appropriate for use throughout a region, for instance, Spanish
content tailored to be useful throughout Latin America. content tailored to be useful throughout Latin America.
The following rules apply to the region subtags: The following rules apply to the region subtags:
1. Region subtags MUST follow any language, extended language, or 1. Region subtags MUST follow any language, extended language, or
script subtags and MUST precede all other subtags. script subtags and MUST precede all other subtags.
2. All two character subtags following the primary subtag were 2. All two-character subtags following the primary subtag were
defined in the IANA registry according to the assignments found defined in the IANA registry according to the assignments found
in [ISO3166-1] ("Codes for the representation of names of in [ISO3166-1] ("Codes for the representation of names of
countries and their subdivisions -- Part 1: Country codes") using countries and their subdivisions -- Part 1: Country codes") using
the list of alpha-2 country codes, or using assignments the list of alpha-2 country codes, or using assignments
subsequently made by the ISO 3166 maintenance agency or governing subsequently made by the ISO 3166 maintenance agency or governing
standardization bodies. standardization bodies.
3. All three character subtags consisting of digit (numeric) 3. All three-character subtags consisting of digit (numeric)
characters following the primary subtag were defined in the IANA characters following the primary subtag were defined in the IANA
registry according to the assignments found in UN Standard registry according to the assignments found in UN Standard
Country or Area Codes for Statistical Use [UN_M.49] or Country or Area Codes for Statistical Use [UN_M.49] or
assignments subsequently made by the governing standards body. assignments subsequently made by the governing standards body.
Note that not all of the UN M.49 codes are defined in the IANA Note that not all of the UN M.49 codes are defined in the IANA
registry. The following rules define which codes are entered registry. The following rules define which codes are entered
into the registry as valid subtags: into the registry as valid subtags:
A. UN numeric codes assigned to 'macro-geographical A. UN numeric codes assigned to 'macro-geographical
(continental)' or sub-regions MUST be registered in the (continental)' or sub-regions MUST be registered in the
skipping to change at page 12, line 35 skipping to change at page 13, line 6
region for which they are defined. region for which they are defined.
D. UN numeric codes for countries or areas for which there is an D. UN numeric codes for countries or areas for which there is an
associated ISO 3166 alpha-2 code in the registry MUST NOT be associated ISO 3166 alpha-2 code in the registry MUST NOT be
entered into the registry and MUST NOT be used to form entered into the registry and MUST NOT be used to form
language tags. Note that the ISO 3166-based subtag in the language tags. Note that the ISO 3166-based subtag in the
registry MUST actually be associated with the UN M.49 code in registry MUST actually be associated with the UN M.49 code in
question. question.
E. UN numeric codes and ISO 3166 alpha-2 codes for countries or E. UN numeric codes and ISO 3166 alpha-2 codes for countries or
areas listed as eligible for registration in [initial- areas listed as eligible for registration in [RFC4645] but
registry] but not presently registered MAY be entered into not presently registered MAY be entered into the IANA
the IANA registry via the process described in Section 3.5. registry via the process described in Section 3.5. Once
Once registered, these codes MAY be used to form language registered, these codes MAY be used to form language tags.
tags.
F. All other UN numeric codes for countries or areas which do F. All other UN numeric codes for countries or areas that do not
not have an associated ISO 3166 alpha-2 code MUST NOT be have an associated ISO 3166 alpha-2 code MUST NOT be entered
entered into the registry and MUST NOT be used to form into the registry and MUST NOT be used to form language tags.
language tags. For more information about these codes, see For more information about these codes, see Section 3.4.
Section 3.4.
4. Note: The alphanumeric codes in Appendix X of the UN document 4. Note: The alphanumeric codes in Appendix X of the UN document
MUST NOT be entered into the registry and MUST NOT be used to MUST NOT be entered into the registry and MUST NOT be used to
form language tags. (At the time this document was created these form language tags. (At the time this document was created,
values match the ISO 3166 alpha-2 codes.) these values matched the ISO 3166 alpha-2 codes.)
5. There MUST be at most one region subtag in a language tag and the 5. There MUST be at most one region subtag in a language tag and the
region subtag MAY be omitted, as when it adds no distinguishing region subtag MAY be omitted, as when it adds no distinguishing
value to the tag. value to the tag.
6. The region subtags 'AA', 'QM'-'QZ', 'XA'-'XZ', and 'ZZ' are 6. The region subtags 'AA', 'QM'-'QZ', 'XA'-'XZ', and 'ZZ' are
reserved for private use in language tags. These subtags reserved for private use in language tags. These subtags
correspond to codes reserved by ISO 3166 for private use. These correspond to codes reserved by ISO 3166 for private use. These
codes MAY be used for private use region subtags (instead of codes MAY be used for private use region subtags (instead of
using a private use subtag sequence). Please refer to using a private use subtag sequence). Please refer to
Section 4.5 for more information on private use subtags. Section 4.5 for more information on private use subtags.
skipping to change at page 13, line 26 skipping to change at page 13, line 43
"sr-Latn-CS" represents Serbian ('sr') written using Latin script "sr-Latn-CS" represents Serbian ('sr') written using Latin script
('Latn') as used in Serbia and Montenegro ('CS'). ('Latn') as used in Serbia and Montenegro ('CS').
"es-419" represents Spanish ('es') appropriate to the UN-defined "es-419" represents Spanish ('es') appropriate to the UN-defined
Latin America and Caribbean region ('419'). Latin America and Caribbean region ('419').
2.2.5. Variant Subtags 2.2.5. Variant Subtags
Variant subtags are used to indicate additional, well-recognized Variant subtags are used to indicate additional, well-recognized
variations that define a language or its dialects which are not variations that define a language or its dialects that are not
covered by other available subtags. The following rules apply to the covered by other available subtags. The following rules apply to the
variant subtags: variant subtags:
1. Variant subtags are not associated with any external standard. 1. Variant subtags are not associated with any external standard.
Variant subtags and their meanings are defined by the Variant subtags and their meanings are defined by the
registration process defined in Section 3.5. registration process defined in Section 3.5.
2. Variant subtags MUST follow all of the other defined subtags, but 2. Variant subtags MUST follow all of the other defined subtags, but
precede any extension or private use subtag sequences. precede any extension or private use subtag sequences.
skipping to change at page 14, line 4 skipping to change at page 14, line 20
of subtags, registrations MUST meet the following length and of subtags, registrations MUST meet the following length and
content restrictions: content restrictions:
1. Variant subtags that begin with a letter (a-z, A-Z) MUST be 1. Variant subtags that begin with a letter (a-z, A-Z) MUST be
at least five characters long. at least five characters long.
2. Variant subtags that begin with a digit (0-9) MUST be at 2. Variant subtags that begin with a digit (0-9) MUST be at
least four characters long. least four characters long.
Variant subtag records in the language subtag registry MAY include Variant subtag records in the language subtag registry MAY include
one or more 'Prefix' fields, which indicates the language tag or tags one or more 'Prefix' fields, which indicate the language tag or tags
that would make a suitable prefix (with other subtags, as that would make a suitable prefix (with other subtags, as
appropriate) in forming a language tag with the variant. For appropriate) in forming a language tag with the variant. For
example, the subtag 'nedis' has a Prefix of "sl", making it suitable example, the subtag 'nedis' has a Prefix of "sl", making it suitable
to form language tags such as "sl-nedis" and "sl-IT-nedis", but not to form language tags such as "sl-nedis" and "sl-IT-nedis", but not
suitable for use in a tag such as "zh-nedis" or "it-IT-nedis". suitable for use in a tag such as "zh-nedis" or "it-IT-nedis".
"sl-nedis" represents the Natisone or Nadiza dialect of Slovenian. "sl-nedis" represents the Natisone or Nadiza dialect of Slovenian.
"de-CH-1996" represents German as used in Switzerland and as written "de-CH-1996" represents German as used in Switzerland and as written
using the spelling reform beginning in the year 1996 C.E. using the spelling reform beginning in the year 1996 C.E.
skipping to change at page 14, line 29 skipping to change at page 14, line 45
spelling reforms. A variant that can meaningfully be used in spelling reforms. A variant that can meaningfully be used in
combination with another variant SHOULD include a 'Prefix' field in combination with another variant SHOULD include a 'Prefix' field in
its registry record that lists that other variant. For example, if its registry record that lists that other variant. For example, if
another German variant 'example' were created that made sense to use another German variant 'example' were created that made sense to use
with '1996', then 'example' should include two Prefix fields: "de" with '1996', then 'example' should include two Prefix fields: "de"
and "de-1996". and "de-1996".
2.2.6. Extension Subtags 2.2.6. Extension Subtags
Extensions provide a mechanism for extending language tags for use in Extensions provide a mechanism for extending language tags for use in
various applications. See: Section 3.7. The following rules apply various applications. See Section 3.7. The following rules apply to
to extensions: extensions:
1. Extension subtags are separated from the other subtags defined 1. Extension subtags are separated from the other subtags defined
in this document by a single character subtag ("singleton"). in this document by a single-character subtag ("singleton").
The singleton MUST be one allocated to a registration authority The singleton MUST be one allocated to a registration authority
via the mechanism described in Section 3.7 and MUST NOT be the via the mechanism described in Section 3.7 and MUST NOT be the
letter 'x', which is reserved for private use subtag sequences. letter 'x', which is reserved for private use subtag sequences.
2. Note: Private use subtag sequences starting with the singleton 2. Note: Private use subtag sequences starting with the singleton
subtag 'x' are described in Section 2.2.7 below. subtag 'x' are described in Section 2.2.7 below.
3. An extension MUST follow at least a primary language subtag. 3. An extension MUST follow at least a primary language subtag.
That is, a language tag cannot begin with an extension. That is, a language tag cannot begin with an extension.
Extensions extend language tags, they do not override or replace Extensions extend language tags, they do not override or replace
them. For example, "a-value" is not a well-formed language tag, them. For example, "a-value" is not a well-formed language tag,
while "de-a-value" is. while "de-a-value" is.
4. Each singleton subtag MUST appear at most one time in each tag 4. Each singleton subtag MUST appear at most one time in each tag
(other than as a private use subtag). That is, singleton (other than as a private use subtag). That is, singleton
subtags MUST NOT be repeated. For example, the tag "en-a-bbb-a- subtags MUST NOT be repeated. For example, the tag
ccc" is invalid because the subtag 'a' appears twice. Note that "en-a-bbb-a-ccc" is invalid because the subtag 'a' appears
the tag "en-a-bbb-x-a-ccc" is valid because the second twice. Note that the tag "en-a-bbb-x-a-ccc" is valid because
appearance of the singleton 'a' is in a private use sequence. the second appearance of the singleton 'a' is in a private use
sequence.
5. Extension subtags MUST meet all of the requirements for the 5. Extension subtags MUST meet all of the requirements for the
content and format of subtags defined in this document. content and format of subtags defined in this document.
6. Extension subtags MUST meet whatever requirements are set by the 6. Extension subtags MUST meet whatever requirements are set by the
document that defines their singleton prefix and whatever document that defines their singleton prefix and whatever
requirements are provided by the maintaining authority. requirements are provided by the maintaining authority.
7. Each extension subtag MUST be from two to eight characters long 7. Each extension subtag MUST be from two to eight characters long
and consist solely of letters or digits, with each subtag and consist solely of letters or digits, with each subtag
separated by a single '-'. separated by a single '-'.
8. Each singleton MUST be followed by at least one extension 8. Each singleton MUST be followed by at least one extension
subtag. For example, the tag "tlh-a-b-foo" is invalid because subtag. For example, the tag "tlh-a-b-foo" is invalid because
the first singleton 'a' is followed immediately by another the first singleton 'a' is followed immediately by another
singleton 'b'. singleton 'b'.
9. Extension subtags MUST follow all language, extended language, 9. Extension subtags MUST follow all language, extended language,
script, region and variant subtags in a tag. script, region, and variant subtags in a tag.
10. All subtags following the singleton and before another singleton 10. All subtags following the singleton and before another singleton
are part of the extension. Example: In the tag "fr-a-Latn", the are part of the extension. Example: In the tag "fr-a-Latn", the
subtag 'Latn' does not represent the script subtag 'Latn' subtag 'Latn' does not represent the script subtag 'Latn'
defined in the IANA Language Subtag Registry. Its meaning is defined in the IANA Language Subtag Registry. Its meaning is
defined by the extension 'a'. defined by the extension 'a'.
11. In the event that more than one extension appears in a single 11. In the event that more than one extension appears in a single
tag, the tag SHOULD be canonicalized as described in tag, the tag SHOULD be canonicalized as described in
Section 4.4. Section 4.4.
For example, if the prefix singleton 'r' and the shown subtags were For example, if the prefix singleton 'r' and the shown subtags were
defined, then the following tag would be a valid example: "en-Latn- defined, then the following tag would be a valid example:
GB-boont-r-extended-sequence-x-private" "en-Latn-GB-boont-r-extended-sequence-x-private".
2.2.7. Private Use Subtags 2.2.7. Private Use Subtags
Private use subtags are used to indicate distinctions in language Private use subtags are used to indicate distinctions in language
important in a given context by private agreement. The following important in a given context by private agreement. The following
rules apply to private use subtags: rules apply to private use subtags:
1. Private use subtags are separated from the other subtags defined 1. Private use subtags are separated from the other subtags defined
in this document by the reserved single-character subtag 'x'. in this document by the reserved single-character subtag 'x'.
skipping to change at page 16, line 26 skipping to change at page 16, line 42
6. Private use subtags are NOT RECOMMENDED where alternatives exist 6. Private use subtags are NOT RECOMMENDED where alternatives exist
or for general interchange. See Section 4.5 for more information or for general interchange. See Section 4.5 for more information
on private use subtag choice. on private use subtag choice.
For example: Users who wished to utilize codes from the Ethnologue For example: Users who wished to utilize codes from the Ethnologue
publication of SIL International for language identification might publication of SIL International for language identification might
agree to exchange tags such as "az-Arab-x-AZE-derbend". This example agree to exchange tags such as "az-Arab-x-AZE-derbend". This example
contains two private use subtags. The first is 'AZE' and the second contains two private use subtags. The first is 'AZE' and the second
is 'derbend'. is 'derbend'.
2.2.8. Pre-Existing RFC 3066 Registrations 2.2.8. Preexisting RFC 3066 Registrations
Existing IANA-registered language tags from RFC 1766 and/or RFC 3066 Existing IANA-registered language tags from RFC 1766 and/or RFC 3066
maintain their validity. These tags will be maintained in the maintain their validity. These tags will be maintained in the
registry in records of either the "grandfathered" or "redundant" registry in records of either the "grandfathered" or "redundant"
type. Grandfathered tags contain one or more subtags that are not type. Grandfathered tags contain one or more subtags that are not
defined in the Language Subtag Registry (see Section 3). Redundant defined in the Language Subtag Registry (see Section 3). Redundant
tags consist entirely of subtags defined above and whose independent tags consist entirely of subtags defined above and whose independent
registration is superseded by this document. For more information registration is superseded by this document. For more information,
see Section 3.8. see Section 3.8.
It is important to note that all language tags formed under the It is important to note that all language tags formed under the
guidelines in this document were either legal, well-formed tags or guidelines in this document were either legal, well-formed tags or
could have been registered under RFC 3066. could have been registered under RFC 3066.
2.2.9. Classes of Conformance 2.2.9. Classes of Conformance
Implementations sometimes need to describe their capabilities with Implementations sometimes need to describe their capabilities with
regard to the rules and practices described in this document. There regard to the rules and practices described in this document. There
skipping to change at page 19, line 4 skipping to change at page 19, line 11
this conceptual entity can be split into a multiple-line this conceptual entity can be split into a multiple-line
representation; this is called "folding". The format of the registry representation; this is called "folding". The format of the registry
is described by the following ABNF (per [RFC4234]): is described by the following ABNF (per [RFC4234]):
registry = record *("%%" CRLF record) registry = record *("%%" CRLF record)
record = 1*( field-name *SP ":" *SP field-body CRLF ) record = 1*( field-name *SP ":" *SP field-body CRLF )
field-name = (ALPHA / DIGIT) [*(ALPHA / DIGIT / "-") (ALPHA / DIGIT)] field-name = (ALPHA / DIGIT) [*(ALPHA / DIGIT / "-") (ALPHA / DIGIT)]
field-body = *(ASCCHAR/LWSP) field-body = *(ASCCHAR/LWSP)
ASCCHAR = %x21-25 / %x27-7E / UNICHAR ; Note: AMPERSAND is %x26 ASCCHAR = %x21-25 / %x27-7E / UNICHAR ; Note: AMPERSAND is %x26
UNICHAR = "&#x" 2*6HEXDIG ";" UNICHAR = "&#x" 2*6HEXDIG ";"
Figure 2: registry format ABNF
Figure 2: Registry Format ABNF
The sequence '..' (%x2E.2E) in a field-body denotes a range of The sequence '..' (%x2E.2E) in a field-body denotes a range of
values. Such a range represents all subtags of the same length that values. Such a range represents all subtags of the same length that
are in alphabetic or numeric order within that range, including the are in alphabetic or numeric order within that range, including the
values explicitly mentioned. For example 'a..c' denotes the values values explicitly mentioned. For example 'a..c' denotes the values
'a', 'b', and 'c' and '11..13' denotes the values '11', '12', and 'a', 'b', and 'c' and '11..13' denotes the values '11', '12', and
'13'. '13'.
Characters from outside the US-ASCII [ISO646] repertoire, as well as Characters from outside the US-ASCII [ISO646] repertoire, as well as
the AMPERSAND character ("&", %x26) when it occurs in a field-body the AMPERSAND character ("&", %x26) when it occurs in a field-body,
are represented by a "Numeric Character Reference" using hexadecimal are represented by a "Numeric Character Reference" using hexadecimal
notation in the style used by [XML10] (see notation in the style used by [XML10] (see
<http://www.w3.org/TR/REC-xml/#dt-charref>). This consists of the <http://www.w3.org/TR/REC-xml/#dt-charref>). This consists of the
sequence "&#x" (%x26.23.78) followed by a hexadecimal representation sequence "&#x" (%x26.23.78) followed by a hexadecimal representation
of the character's code point in [ISO10646] followed by a closing of the character's code point in [ISO10646] followed by a closing
semicolon (%x3B). For example, the EURO SIGN, U+20AC, would be semicolon (%x3B). For example, the EURO SIGN, U+20AC, would be
represented by the sequence "&#x20AC;". Note that the hexadecimal represented by the sequence "&#x20AC;". Note that the hexadecimal
notation MAY have between two and six digits. notation MAY have between two and six digits.
All fields whose field-body contains a date value use the "full-date" All fields whose field-body contains a date value use the "full-date"
format specified in [RFC3339]. For example: "2004-06-28" represents format specified in [RFC3339]. For example: "2004-06-28" represents
June 28, 2004 in the Gregorian calendar. June 28, 2004, in the Gregorian calendar.
The first record in the file contains the single field whose field- The first record in the file contains the single field whose field-
name is "File-Date". The field-body of this record contains the last name is "File-Date" (see Figure 3). The field-body of this record
modification date of this copy of the registry, making it possible to contains the last modification date of this copy of the registry,
compare different versions of the registry. The registry on the IANA making it possible to compare different versions of the registry.
website is the most current. Versions with an older date than that The registry on the IANA website is the most current. Versions with
one are not up-to-date. an older date than that one are not up-to-date.
File-Date: 2004-06-28 File-Date: 2004-06-28
%% %%
Figure 3: Example of the File-Date Record Figure 3: Example of the File-Date Record
Subsequent records represent subtags in the registry. Each of the Subsequent records represent subtags in the registry. Each of the
fields in each record MUST occur no more than once, unless otherwise fields in each record MUST occur no more than once, unless otherwise
noted below. Each record MUST contain the following fields: noted below. Each record MUST contain the following fields:
skipping to change at page 20, line 46 skipping to change at page 21, line 6
description of the tag or subtag in the record. At least one of the description of the tag or subtag in the record. At least one of the
'Description' fields MUST be written or transcribed into the Latin 'Description' fields MUST be written or transcribed into the Latin
script; the same or additional fields MAY also include a description script; the same or additional fields MAY also include a description
in a non-Latin script. The 'Description' field is used for in a non-Latin script. The 'Description' field is used for
identification purposes and SHOULD NOT be taken to represent the identification purposes and SHOULD NOT be taken to represent the
actual native name of the language or variation or to be in any actual native name of the language or variation or to be in any
particular language. Most descriptions are taken directly from particular language. Most descriptions are taken directly from
source standards such as ISO 639 or ISO 3166. source standards such as ISO 639 or ISO 3166.
Note: Descriptions in registry entries that correspond to ISO 639, Note: Descriptions in registry entries that correspond to ISO 639,
ISO 15924, ISO 3166 or UN M.49 codes are intended only to indicate ISO 15924, ISO 3166, or UN M.49 codes are intended only to indicate
the meaning of that identifier as defined in the source standard at the meaning of that identifier as defined in the source standard at
the time it was added to the registry. The description does not the time it was added to the registry. The description does not
replace the content of the source standard itself. The descriptions replace the content of the source standard itself. The descriptions
are not intended to be the English localized names for the subtags. are not intended to be the English localized names for the subtags.
Localization or translation of language tag and subtag descriptions Localization or translation of language tag and subtag descriptions
is out of scope of this document. is out of scope of this document.
Each record MAY also contain the following fields: Each record MAY also contain the following fields:
o Preferred-Value o Preferred-Value
* For fields of type 'language', 'extlang', 'script', 'region', * For fields of type 'language', 'extlang', 'script', 'region',
and 'variant', 'Preferred-Value' contains a subtag of the same and 'variant', 'Preferred-Value' contains the subtag of the
'Type' which is preferred for forming the language tag. same 'Type' that is preferred for forming the language tag.
* For fields of type 'grandfathered' and 'redundant', a canonical * For fields of type 'grandfathered' and 'redundant', a canonical
mapping to a complete language tag. mapping to a complete language tag.
o Deprecated o Deprecated
* Deprecated's field-value contains the date the record was * Deprecated's field-value contains the date the record was
deprecated. deprecated.
o Prefix o Prefix
skipping to change at page 21, line 46 skipping to change at page 22, line 7
o Suppress-Script o Suppress-Script
* Suppress-Script contains a script subtag that SHOULD NOT be * Suppress-Script contains a script subtag that SHOULD NOT be
used to form language tags with the associated primary language used to form language tags with the associated primary language
subtag. This field MUST only appear in records whose 'Type' subtag. This field MUST only appear in records whose 'Type'
field-value is 'language'. See Section 4.1. field-value is 'language'. See Section 4.1.
The field 'Deprecated' MAY be added to any record via the maintenance The field 'Deprecated' MAY be added to any record via the maintenance
process described in Section 3.3 or via the registration process process described in Section 3.3 or via the registration process
described in Section 3.5. Usually the addition of a 'Deprecated' described in Section 3.5. Usually, the addition of a 'Deprecated'
field is due to the action of one of the standards bodies, such as field is due to the action of one of the standards bodies, such as
ISO 3166, withdrawing a code. In some historical cases it might not ISO 3166, withdrawing a code. In some historical cases, it might not
have been possible to reconstruct the original deprecation date. For have been possible to reconstruct the original deprecation date. For
these cases, an approximate date appears in the registry. Although these cases, an approximate date appears in the registry. Although
valid in language tags, subtags and tags with a 'Deprecated' field valid in language tags, subtags and tags with a 'Deprecated' field
are deprecated and validating processors SHOULD NOT generate these are deprecated and validating processors SHOULD NOT generate these
subtags. Note that a record that contains a 'Deprecated' field and subtags. Note that a record that contains a 'Deprecated' field and
no corresponding 'Preferred-Value' field has no replacement mapping. no corresponding 'Preferred-Value' field has no replacement mapping.
The field 'Preferred-Value' contains a mapping between the record in The field 'Preferred-Value' contains a mapping between the record in
which it appears and another tag or subtag. The value in this field which it appears and another tag or subtag. The value in this field
is STRONGLY RECOMMENDED as the best choice to represent the value of is STRONGLY RECOMMENDED as the best choice to represent the value of
this record when selecting a language tag. These values form three this record when selecting a language tag. These values form three
groups: groups:
1. ISO 639 language codes which were later withdrawn in favor of 1. ISO 639 language codes that were later withdrawn in favor of
other codes. These values are mostly a historical curiosity. other codes. These values are mostly a historical curiosity.
2. ISO 3166 region codes which have been withdrawn in favor of a new 2. ISO 3166 region codes that have been withdrawn in favor of a new
code. This sometimes happens when a country changes its name or code. This sometimes happens when a country changes its name or
administration in such a way that warrants a new region code. administration in such a way that warrants a new region code.
3. Tags grandfathered from RFC 3066. In many cases these tags have 3. Tags grandfathered from RFC 3066. In many cases, these tags have
become obsolete because the values they represent were later become obsolete because the values they represent were later
encoded by ISO 639. encoded by ISO 639.
Records that contain a 'Preferred-Value' field MUST also have a Records that contain a 'Preferred-Value' field MUST also have a
'Deprecated' field. This field contains a date of deprecation. Thus 'Deprecated' field. This field contains a date of deprecation.
a language tag processor can use the registry to construct the valid, Thus, a language tag processor can use the registry to construct the
non-deprecated set of subtags for a given date. In addition, for any valid, non-deprecated set of subtags for a given date. In addition,
given tag, a processor can construct the set of valid language tags for any given tag, a processor can construct the set of valid
that correspond to that tag for all dates up to the date of the language tags that correspond to that tag for all dates up to the
registry. The ability to do these mappings MAY be beneficial to date of the registry. The ability to do these mappings MAY be
applications that are matching, selecting, for filtering content beneficial to applications that are matching, selecting, for
based on its language tags. filtering content based on its language tags.
Note that 'Preferred-Value' mappings in records of type 'region' Note that 'Preferred-Value' mappings in records of type 'region'
sometimes do not represent exactly the same meaning as the original sometimes do not represent exactly the same meaning as the original
value. There are many reasons for a country code to be changed and value. There are many reasons for a country code to be changed, and
the effect this has on the formation of language tags will depend on the effect this has on the formation of language tags will depend on
the nature of the change in question. the nature of the change in question.
In particular, the 'Preferred-Value' field does not imply retagging In particular, the 'Preferred-Value' field does not imply retagging
content that uses the affected subtag. content that uses the affected subtag.
The field 'Preferred-Value' MUST NOT be modified once created in the The field 'Preferred-Value' MUST NOT be modified once created in the
registry. The field MAY be added to records of type "grandfathered" registry. The field MAY be added to records of type "grandfathered"
and "region" according to the rules in Section 3.3. Otherwise the and "region" according to the rules in Section 3.3. Otherwise the
field MUST NOT be added to any record already in the registry. field MUST NOT be added to any record already in the registry.
The 'Preferred-Value' field in records of type "grandfathered" and The 'Preferred-Value' field in records of type "grandfathered" and
"redundant" contains whole language tags that are strongly "redundant" contains whole language tags that are strongly
RECOMMENDED for use in place of the record's value. In many cases RECOMMENDED for use in place of the record's value. In many cases,
the mappings were created by deprecation of the tags during the the mappings were created by deprecation of the tags during the
period before this document was adopted. For example, the tag "no- period before this document was adopted. For example, the tag
nyn" was deprecated in favor of the ISO 639-1 defined language code "no-nyn" was deprecated in favor of the ISO 639-1-defined language
'nn'. code 'nn'.
Records of type 'variant' MAY have more than one field of type Records of type 'variant' MAY have more than one field of type
'Prefix'. Additional fields of this type MAY be added to a 'variant' 'Prefix'. Additional fields of this type MAY be added to a 'variant'
record via the registration process. record via the registration process.
Records of type 'extlang' MUST have _exactly_ one 'Prefix' field. Records of type 'extlang' MUST have _exactly_ one 'Prefix' field.
The field-value of the 'Prefix' field consists of a language tag The field-value of the 'Prefix' field consists of a language tag
whose subtags are appropriate to use with this subtag. For example, whose subtags are appropriate to use with this subtag. For example,
the variant subtag '1996' has a Prefix field of "de". This means the variant subtag '1996' has a 'Prefix' field of "de". This means
that tags starting with the sequence "de-" are appropriate with this that tags starting with the sequence "de-" are appropriate with this
subtag, so "de-Latg-1996" and "de-CH-1996" are both acceptable, while subtag, so "de-Latg-1996" and "de-CH-1996" are both acceptable, while
the tag "fr-1996" is an inappropriate choice. the tag "fr-1996" is an inappropriate choice.
The field of type 'Prefix' MUST NOT be removed from any record. The The field of type 'Prefix' MUST NOT be removed from any record. The
field-value for this type of field MUST NOT be modified. field-value for this type of field MUST NOT be modified.
The field 'Comments' MAY appear more than once per record. This The field 'Comments' MAY appear more than once per record. This
field MAY be inserted or changed via the registration process and no field MAY be inserted or changed via the registration process and no
guarantee of stability is provided. The content of this field is not guarantee of stability is provided. The content of this field is not
restricted, except by the need to register the information, the restricted, except by the need to register the information, the
suitability of the request, and by reasonable practical size suitability of the request, and by reasonable practical size
limitations. limitations.
The field 'Suppress-Script' MUST only appear in records whose 'Type' The field 'Suppress-Script' MUST only appear in records whose 'Type'
field-value is 'language'. This field MUST NOT appear more than one field-value is 'language'. This field MUST NOT appear more than one
time in a record. This field indicates a script used to write the time in a record. This field indicates a script used to write the
overwhelming majority of documents for the given language and which overwhelming majority of documents for the given language and that
therefore adds no distinguishing information to a language tag. It therefore adds no distinguishing information to a language tag. It
helps ensure greater compatibility between the language tags helps ensure greater compatibility between the language tags
generated according to the rules in this document and language tags generated according to the rules in this document and language tags
and tag processors or consumers based on RFC 3066. For example, and tag processors or consumers based on RFC 3066. For example,
virtually all Icelandic documents are written in the Latin script, virtually all Icelandic documents are written in the Latin script,
making the subtag 'Latn' redundant in the tag "is-Latn". making the subtag 'Latn' redundant in the tag "is-Latn".
3.2. Language Subtag Reviewer 3.2. Language Subtag Reviewer
The Language Subtag Reviewer is appointed by the IESG for an The Language Subtag Reviewer is appointed by the IESG for an
indefinite term, subject to removal or replacement at the IESG's indefinite term, subject to removal or replacement at the IESG's
discretion. The Language Subtag Reviewer moderates the ietf- discretion. The Language Subtag Reviewer moderates the ietf-
languages mailing list, responds to requests for registration, and languages mailing list, responds to requests for registration, and
performs the other registry maintenance duties described in performs the other registry maintenance duties described in
Section 3.3. Only the Language Subtag Reviewer is permitted to Section 3.3. Only the Language Subtag Reviewer is permitted to
request IANA to change, update or add records to the Language Subtag request IANA to change, update, or add records to the Language Subtag
Registry. Registry.
The performance or decisions of the Language Subtag Reviewer MAY be The performance or decisions of the Language Subtag Reviewer MAY be
appealed to the IESG under the same rules as other IETF decisions appealed to the IESG under the same rules as other IETF decisions
(see [RFC2026]). The IESG can reverse or overturn the decision of (see [RFC2026]). The IESG can reverse or overturn the decision of
the Language Subtag Reviewer, provide guidance, or take other the Language Subtag Reviewer, provide guidance, or take other
appropriate actions. appropriate actions.
3.3. Maintenance of the Registry 3.3. Maintenance of the Registry
skipping to change at page 24, line 32 skipping to change at page 24, line 43
Note: The redundant and grandfathered entries together are the Note: The redundant and grandfathered entries together are the
complete list of tags registered under [RFC3066]. The redundant tags complete list of tags registered under [RFC3066]. The redundant tags
are those that can now be formed using the subtags defined in the are those that can now be formed using the subtags defined in the
registry together with the rules of Section 2.2. The grandfathered registry together with the rules of Section 2.2. The grandfathered
entries include those that can never be legal under those same entries include those that can never be legal under those same
provisions. provisions.
The set of redundant and grandfathered tags is permanent and stable: The set of redundant and grandfathered tags is permanent and stable:
new entries in this section MUST NOT be added and existing entries new entries in this section MUST NOT be added and existing entries
MUST NOT be removed. Records of type 'grandfathered' MAY have their MUST NOT be removed. Records of type 'grandfathered' MAY have their
type converted to 'redundant': see item 12 in Section 3.6 for more type converted to 'redundant'; see item 12 in Section 3.6 for more
information. The decision making process about which tags were information. The decision-making process about which tags were
initially grandfathered and which were made redundant is described in initially grandfathered and which were made redundant is described in
[initial-registry]. [RFC4645].
RFC 3066 tags that were deprecated prior to the adoption of this RFC 3066 tags that were deprecated prior to the adoption of this
document are part of the list of grandfathered tags and their document are part of the list of grandfathered tags, and their
component subtags were not included as registered variants (although component subtags were not included as registered variants (although
they remain eligible for registration). For example, the tag "art- they remain eligible for registration). For example, the tag
lojban" was deprecated in favor of the language subtag 'jbo'. "art-lojban" was deprecated in favor of the language subtag 'jbo'.
The Language Subtag Reviewer MUST ensure that new subtags meet the The Language Subtag Reviewer MUST ensure that new subtags meet the
requirements in Section 4.1 or submit an appropriate alternate subtag requirements in Section 4.1 or submit an appropriate alternate subtag
as described in that section. When either a change or addition to as described in that section. When either a change or addition to
the registry is needed, the Language Subtag Reviewer MUST prepare the the registry is needed, the Language Subtag Reviewer MUST prepare the
complete record, including all fields, and forward it to IANA for complete record, including all fields, and forward it to IANA for
insertion into the registry. Each record being modified or inserted insertion into the registry. Each record being modified or inserted
MUST be forwarded in a separate message. MUST be forwarded in a separate message.
If a record represents a new subtag that does not currently exist in If a record represents a new subtag that does not currently exist in
skipping to change at page 25, line 25 skipping to change at page 25, line 36
Description: Natisone dialect Description: Natisone dialect
Description: Nadiza dialect Description: Nadiza dialect
Added: 2003-10-09 Added: 2003-10-09
Prefix: sl Prefix: sl
Comments: This is a comment shown Comments: This is a comment shown
as an example. as an example.
%% %%
Figure 4: Example of a Language Subtag Modification Form Figure 4: Example of a Language Subtag Modification Form
Whenever an entry is created or modified in the registry, the 'File- Whenever an entry is created or modified in the registry, the
Date' record at the start of the registry is updated to reflect the 'File-Date' record at the start of the registry is updated to reflect
most recent modification date in the [RFC3339] "full-date" format. the most recent modification date in the [RFC3339] "full-date"
format.
Before forwarding a new registration to IANA, the Language Subtag Before forwarding a new registration to IANA, the Language Subtag
Reviewer MUST ensure that values in the 'Subtag' field match case Reviewer MUST ensure that values in the 'Subtag' field match case
according to the description in Section 3.1. according to the description in Section 3.1.
3.4. Stability of IANA Registry Entries 3.4. Stability of IANA Registry Entries
The stability of entries and their meaning in the registry is The stability of entries and their meaning in the registry is
critical to the long term stability of language tags. The rules in critical to the long-term stability of language tags. The rules in
this section guarantee that a specific language tag's meaning is this section guarantee that a specific language tag's meaning is
stable over time and will not change. stable over time and will not change.
These rules specifically deal with how changes to codes (including These rules specifically deal with how changes to codes (including
withdrawal and deprecation of codes) maintained by ISO 639, ISO withdrawal and deprecation of codes) maintained by ISO 639, ISO
15924, ISO 3166, and UN M.49 are reflected in the IANA Language 15924, ISO 3166, and UN M.49 are reflected in the IANA Language
Subtag Registry. Assignments to the IANA Language Subtag Registry Subtag Registry. Assignments to the IANA Language Subtag Registry
MUST follow the following stability rules: MUST follow the following stability rules:
1. Values in the fields 'Type', 'Subtag', 'Tag', 'Added', 1. Values in the fields 'Type', 'Subtag', 'Tag', 'Added',
'Deprecated' and 'Preferred-Value' MUST NOT be changed and are 'Deprecated' and 'Preferred-Value' MUST NOT be changed and are
guaranteed to be stable over time. guaranteed to be stable over time.
2. Values in the 'Description' field MUST NOT be changed in a way 2. Values in the 'Description' field MUST NOT be changed in a way
that would invalidate previously-existing tags. They MAY be that would invalidate previously-existing tags. They MAY be
broadened somewhat in scope, changed to add information, or broadened somewhat in scope, changed to add information, or
adapted to the most common modern usage. For example, countries adapted to the most common modern usage. For example, countries
occasionally change their official names: an historical example occasionally change their official names; a historical example
of this would be "Upper Volta" changing to "Burkina Faso". of this would be "Upper Volta" changing to "Burkina Faso".
3. Values in the field 'Prefix' MAY be added to records of type 3. Values in the field 'Prefix' MAY be added to records of type
'variant' via the registration process. 'variant' via the registration process.
4. Values in the field 'Prefix' MAY be modified, so long as the 4. Values in the field 'Prefix' MAY be modified, so long as the
modifications broaden the set of prefixes. That is, a prefix modifications broaden the set of prefixes. That is, a prefix
MAY be replaced by one of its own prefixes. For example, the MAY be replaced by one of its own prefixes. For example, the
prefix "en-US" could be replaced by "en", but not by the prefix "en-US" could be replaced by "en", but not by the
prefixes "en-Latn", "fr", or "en-US-boont". If one of those prefixes "en-Latn", "fr", or "en-US-boont". If one of those
skipping to change at page 26, line 42 skipping to change at page 27, line 8
9. Codes assigned by ISO 639, ISO 15924, or ISO 3166 that are 9. Codes assigned by ISO 639, ISO 15924, or ISO 3166 that are
withdrawn by their respective maintenance or registration withdrawn by their respective maintenance or registration
authority remain valid in language tags. A 'Deprecated' field authority remain valid in language tags. A 'Deprecated' field
containing the date of withdrawal is added to the record. If a containing the date of withdrawal is added to the record. If a
new record of the same type is added that represents a new record of the same type is added that represents a
replacement value, then a 'Preferred-Value' field MAY also be replacement value, then a 'Preferred-Value' field MAY also be
added. The registration process MAY be used to add comments added. The registration process MAY be used to add comments
about the withdrawal of the code by the respective standard. about the withdrawal of the code by the respective standard.
Example The region code 'TL' was assigned to the country 'Timor- Example
The region code 'TL' was assigned to the country 'Timor-
Leste', replacing the code 'TP' (which was assigned to 'East Leste', replacing the code 'TP' (which was assigned to 'East
Timor' when it was under administration by Portugal). The Timor' when it was under administration by Portugal). The
subtag 'TP' remains valid in language tags, but its record subtag 'TP' remains valid in language tags, but its record
contains the a 'Preferred-Value' of 'TL' and its field contains the a 'Preferred-Value' of 'TL' and its field
'Deprecated' contains the date the new code was assigned 'Deprecated' contains the date the new code was assigned
('2004-07-06'). ('2004-07-06').
10. Codes assigned by ISO 639, ISO 15924, or ISO 3166 that conflict 10. Codes assigned by ISO 639, ISO 15924, or ISO 3166 that conflict
with existing subtags of the associated type, including subtags with existing subtags of the associated type, including subtags
that are deprecated, MUST NOT be entered into the registry. The that are deprecated, MUST NOT be entered into the registry. The
skipping to change at page 27, line 22 skipping to change at page 27, line 34
not represented by a subtag in the IANA registry, the not represented by a subtag in the IANA registry, the
Language Subtag Reviewer, as described in Section 3.5, SHALL Language Subtag Reviewer, as described in Section 3.5, SHALL
prepare a proposal for entering in the IANA registry as soon prepare a proposal for entering in the IANA registry as soon
as practical a registered language subtag as an alternate as practical a registered language subtag as an alternate
value for the new code. The form of the registered language value for the new code. The form of the registered language
subtag will be at the discretion of the Language Subtag subtag will be at the discretion of the Language Subtag
Reviewer and MUST conform to other restrictions on language Reviewer and MUST conform to other restrictions on language
subtags in this document. subtags in this document.
B. For all subtags whose meaning is derived from an external B. For all subtags whose meaning is derived from an external
standard (i.e. ISO 639, ISO 15924, ISO 3166, or UN M.49), standard (i.e., ISO 639, ISO 15924, ISO 3166, or UN M.49),
if a new meaning is assigned to an existing code and the new if a new meaning is assigned to an existing code and the new
meaning broadens the meaning of that code, then the meaning meaning broadens the meaning of that code, then the meaning
for the associated subtag MAY be changed to match. The for the associated subtag MAY be changed to match. The
meaning of a subtag MUST NOT be narrowed, however, as this meaning of a subtag MUST NOT be narrowed, however, as this
can result in an unknown proportion of the existing uses of can result in an unknown proportion of the existing uses of
a subtag becoming invalid. Note: ISO 639 MA/RA has adopted a subtag becoming invalid. Note: ISO 639 maintenance
a similar stability policy. agency/registration authority (MA/RA) has adopted a similar
stability policy.
C. For ISO 15924 codes, if the newly assigned code's meaning is C. For ISO 15924 codes, if the newly assigned code's meaning is
not represented by a subtag in the IANA registry, the not represented by a subtag in the IANA registry, the
Language Subtag Reviewer, as described in Section 3.5, SHALL Language Subtag Reviewer, as described in Section 3.5, SHALL
prepare a proposal for entering in the IANA registry as soon prepare a proposal for entering in the IANA registry as soon
as practical a registered variant subtag as an alternate as practical a registered variant subtag as an alternate
value for the new code. The form of the registered variant value for the new code. The form of the registered variant
subtag will be at the discretion of the Language Subtag subtag will be at the discretion of the Language Subtag
Reviewer and MUST conform to other restrictions on variant Reviewer and MUST conform to other restrictions on variant
subtags in this document. subtags in this document.
skipping to change at page 28, line 31 skipping to change at page 28, line 47
there is no corresponding ISO 3166 code SHOULD NOT be there is no corresponding ISO 3166 code SHOULD NOT be
registered, except as a surrogate for an ISO 3166 code that is registered, except as a surrogate for an ISO 3166 code that is
blocked from registration by an existing subtag. If such a code blocked from registration by an existing subtag. If such a code
becomes necessary, then the registration authority for ISO 3166 becomes necessary, then the registration authority for ISO 3166
SHOULD first be petitioned to assign a code to the region. If SHOULD first be petitioned to assign a code to the region. If
the petition for a code assignment by ISO 3166 is refused or not the petition for a code assignment by ISO 3166 is refused or not
acted on in a timely manner, the registration process described acted on in a timely manner, the registration process described
in Section 3.5 MAY then be used to register the corresponding UN in Section 3.5 MAY then be used to register the corresponding UN
M.49 code. At the time this document was written, there were M.49 code. At the time this document was written, there were
only four such codes: 830 (Channel Islands), 831 (Guernsey), 832 only four such codes: 830 (Channel Islands), 831 (Guernsey), 832
(Jersey), and 833 (Isle of Man). This way UN M.49 codes remain (Jersey), and 833 (Isle of Man). This way, UN M.49 codes remain
available as the value of last resort in cases where ISO 3166 available as the value of last resort in cases where ISO 3166
reassigns a deprecated value in the registry. reassigns a deprecated value in the registry.
12. Stability provisions apply to grandfathered tags with this 12. Stability provisions apply to grandfathered tags with this
exception: should all of the subtags in a grandfathered tag exception: should all of the subtags in a grandfathered tag
become valid subtags in the IANA registry, then the field 'Type' become valid subtags in the IANA registry, then the field 'Type'
in that record is changed from 'grandfathered' to 'redundant'. in that record is changed from 'grandfathered' to 'redundant'.
Note that this will not affect language tags that match the Note that this will not affect language tags that match the
grandfathered tag, since these tags will now match valid grandfathered tag, since these tags will now match valid
generative subtag sequences. For example, if the subtag 'gan' generative subtag sequences. For example, if the subtag 'gan'
skipping to change at page 29, line 13 skipping to change at page 29, line 30
subtag not currently in the IANA Language Subtag Registry. subtag not currently in the IANA Language Subtag Registry.
Only subtags of type 'language' and 'variant' will be considered for Only subtags of type 'language' and 'variant' will be considered for
independent registration of new subtags. Handling of subtags needed independent registration of new subtags. Handling of subtags needed
for stability and subtags necessary to keep the registry synchronized for stability and subtags necessary to keep the registry synchronized
with ISO 639, ISO 15924, ISO 3166, and UN M.49 within the limits with ISO 639, ISO 15924, ISO 3166, and UN M.49 within the limits
defined by this document are described in Section 3.3. Stability defined by this document are described in Section 3.3. Stability
provisions are described in Section 3.4. provisions are described in Section 3.4.
This procedure MAY also be used to register or alter the information This procedure MAY also be used to register or alter the information
for the "Description", "Comments", "Deprecated", or "Prefix" fields for the 'Description', 'Comments', 'Deprecated', or 'Prefix' fields
in a subtag's record as described in Section 3.4. Changes to all in a subtag's record as described in Section 3.4. Changes to all
other fields in the IANA registry are NOT permitted. other fields in the IANA registry are NOT permitted.
Registering a new subtag or requesting modifications to an existing Registering a new subtag or requesting modifications to an existing
tag or subtag starts with the requester filling out the registration tag or subtag starts with the requester filling out the registration
form reproduced below. Note that each response is not limited in form reproduced below. Note that each response is not limited in
size so that the request can adequately describe the registration. size so that the request can adequately describe the registration.
The fields in the "Record Requested" section SHOULD follow the The fields in the "Record Requested" section SHOULD follow the
requirements in Section 3.1. requirements in Section 3.1.
skipping to change at page 29, line 46 skipping to change at page 30, line 27
Comments: Comments:
4. Intended meaning of the subtag: 4. Intended meaning of the subtag:
5. Reference to published description 5. Reference to published description
of the language (book or article): of the language (book or article):
6. Any other relevant information: 6. Any other relevant information:
Figure 5: The Language Subtag Registration Form Figure 5: The Language Subtag Registration Form
The subtag registration form MUST be sent to The subtag registration form MUST be sent to
<ietf-languages@iana.org> for a two week review period before it can <ietf-languages@iana.org> for a two-week review period before it can
be submitted to IANA. (This is an open list and can be joined by be submitted to IANA. (This is an open list and can be joined by
sending a request to <ietf-languages-request@iana.org>.) sending a request to <ietf-languages-request@iana.org>.)
Variant subtags are usually registered for use with a particular Variant subtags are usually registered for use with a particular
range of language tags. For example, the subtag 'rozaj' is intended range of language tags. For example, the subtag 'rozaj' is intended
for use with language tags that start with the primary language for use with language tags that start with the primary language
subtag "sl", since Resian is a dialect of Slovenian. Thus the subtag subtag "sl", since Resian is a dialect of Slovenian. Thus, the
'rozaj' would be appropriate in tags such as "sl-Latn-rozaj" or "sl- subtag 'rozaj' would be appropriate in tags such as "sl-Latn-rozaj"
IT-rozaj". This information is stored in the "Prefix" field in the or "sl-IT-rozaj". This information is stored in the 'Prefix' field
registry. Variant registration requests SHOULD include at least one in the registry. Variant registration requests SHOULD include at
"Prefix" field in the registration form. least one 'Prefix' field in the registration form.
Extended language subtags are reserved for future standardization. Extended language subtags are reserved for future standardization.
These subtags will be REQUIRED to include exactly one "Prefix" field These subtags will be REQUIRED to include exactly one 'Prefix' field
once they are allowed for registration. once they are allowed for registration.
The 'Prefix' field for a given registered subtag exists in the IANA The 'Prefix' field for a given registered subtag exists in the IANA
registry as a guide to usage. Additional prefixes MAY be added by registry as a guide to usage. Additional prefixes MAY be added by
filing an additional registration form. In that form, the "Any other filing an additional registration form. In that form, the "Any other
relevant information:" field MUST indicate that it is the addition of relevant information:" field MUST indicate that it is the addition of
a prefix. a prefix.
Requests to add a prefix to a variant subtag that imply a different Requests to add a prefix to a variant subtag that imply a different
semantic meaning will probably be rejected. For example, a request semantic meaning will probably be rejected. For example, a request
to add the prefix "de" to the subtag 'nedis' so that the tag "de- to add the prefix "de" to the subtag 'nedis' so that the tag
nedis" represented some German dialect would be rejected. The "de-nedis" represented some German dialect would be rejected. The
'nedis' subtag represents a particular Slovenian dialect and the 'nedis' subtag represents a particular Slovenian dialect and the
additional registration would change the semantic meaning assigned to additional registration would change the semantic meaning assigned to
the subtag. A separate subtag SHOULD be proposed instead. the subtag. A separate subtag SHOULD be proposed instead.
The 'Description' field MUST contain a description of the tag being The 'Description' field MUST contain a description of the tag being
registered written or transcribed into the Latin script; it MAY also registered written or transcribed into the Latin script; it MAY also
include a description in a non-Latin script. Non-ASCII characters include a description in a non-Latin script. Non-ASCII characters
MUST be escaped using the syntax described in Section 3.1. The MUST be escaped using the syntax described in Section 3.1. The
'Description' field is used for identification purposes and doesn't 'Description' field is used for identification purposes and doesn't
necessarily represent the actual native name of the language or necessarily represent the actual native name of the language or
variation or to be in any particular language. variation or to be in any particular language.
While the 'Description' field itself is not guaranteed to be stable While the 'Description' field itself is not guaranteed to be stable
and errata corrections MAY be undertaken from time to time, attempts and errata corrections MAY be undertaken from time to time, attempts
to provide translations or transcriptions of entries in the registry to provide translations or transcriptions of entries in the registry
itself will probably be frowned upon by the community or rejected itself will probably be frowned upon by the community or rejected
outright, as changes of this nature have an impact on the provisions outright, as changes of this nature have an impact on the provisions
in Section 3.4. in Section 3.4.
When the two week period has passed the Language Subtag Reviewer When the two-week period has passed, the Language Subtag Reviewer
either forwards the record to be inserted or modified to either forwards the record to be inserted or modified to
iana@iana.org according to the procedure described in Section 3.3, or iana@iana.org according to the procedure described in Section 3.3, or
rejects the request because of significant objections raised on the rejects the request because of significant objections raised on the
list or due to problems with constraints in this document (which MUST list or due to problems with constraints in this document (which MUST
be explicitly cited). The Language Subtag Reviewer MAY also extend be explicitly cited). The Language Subtag Reviewer MAY also extend
the review period in two week increments to permit further the review period in two-week increments to permit further
discussion. The Language Subtag Reviewer MUST indicate on the list discussion. The Language Subtag Reviewer MUST indicate on the list
whether the registration has been accepted, rejected, or extended whether the registration has been accepted, rejected, or extended
following each two week period. following each two-week period.
Note that the Language Subtag Reviewer MAY raise objections on the Note that the Language Subtag Reviewer MAY raise objections on the
list if he or she so desires. The important thing is that the list if he or she so desires. The important thing is that the
objection MUST be made publicly. objection MUST be made publicly.
The applicant is free to modify a rejected application with The applicant is free to modify a rejected application with
additional information and submit it again; this restarts the two additional information and submit it again; this restarts the two-
week comment period. week comment period.
Decisions made by the Language Subtag Reviewer MAY be appealed to the Decisions made by the Language Subtag Reviewer MAY be appealed to the
IESG [RFC2028] under the same rules as other IETF decisions IESG [RFC2028] under the same rules as other IETF decisions
[RFC2026]. [RFC2026].
All approved registration forms are available online in the directory All approved registration forms are available online in the directory
http://www.iana.org/numbers.html under "languages". http://www.iana.org/numbers.html under "languages".
Updates or changes to existing records follow the same procedure as Updates or changes to existing records follow the same procedure as
new registrations. The Language Subtag Reviewer decides whether new registrations. The Language Subtag Reviewer decides whether
there is consensus to update the registration following the two week there is consensus to update the registration following the two-week
review period; normally objections by the original registrant will review period; normally, objections by the original registrant will
carry extra weight in forming such a consensus. carry extra weight in forming such a consensus.
Registrations are permanent and stable. Once registered, subtags Registrations are permanent and stable. Once registered, subtags
will not be removed from the registry and will remain a valid way in will not be removed from the registry and will remain a valid way in
which to specify a specific language or variant. which to specify a specific language or variant.
Note: The purpose of the "Description" in the registration form is Note: The purpose of the "Description" in the registration form is to
intended as an aid to people trying to verify whether a language is aid people trying to verify whether a language is registered or what
registered or what language or language variation a particular subtag language or language variation a particular subtag refers to. In
refers to. In most cases, reference to an authoritative grammar or most cases, reference to an authoritative grammar or dictionary of
dictionary of that language will be useful; in cases where no such that language will be useful; in cases where no such work exists,
work exists, other well known works describing that language or in other well-known works describing that language or in that language
that language MAY be appropriate. The Language Subtag Reviewer MAY be appropriate. The Language Subtag Reviewer decides what
decides what constitutes "good enough" reference material. This constitutes "good enough" reference material. This requirement is
requirement is not intended to exclude particular languages or not intended to exclude particular languages or dialects due to the
dialects due to the size of the speaker population or lack of a size of the speaker population or lack of a standardized orthography.
standardized orthography. Minority languages will be considered Minority languages will be considered equally on their own merits.
equally on their own merits.
3.6. Possibilities for Registration 3.6. Possibilities for Registration
Possibilities for registration of subtags or information about Possibilities for registration of subtags or information about
subtags include: subtags include:
o Primary language subtags for languages not listed in ISO 639 that o Primary language subtags for languages not listed in ISO 639 that
are not variants of any listed or registered language MAY be are not variants of any listed or registered language MAY be
registered. At the time this document was created there were no registered. At the time this document was created, there were no
examples of this form of subtag. Before attempting to register a examples of this form of subtag. Before attempting to register a
language subtag, there MUST be an attempt to register the language language subtag, there MUST be an attempt to register the language
with ISO 639. Subtags MUST NOT be registered for codes that exist with ISO 639. Subtags MUST NOT be registered for codes that exist
in ISO 639-1 or ISO 639-2, which are under consideration by the in ISO 639-1 or ISO 639-2, that are under consideration by the ISO
ISO 639 maintenance or registration authorities, or which have 639 maintenance or registration authorities, or that have never
never been attempted for registration with those authorities. If been attempted for registration with those authorities. If ISO
ISO 639 has previously rejected a language for registration, it is 639 has previously rejected a language for registration, it is
reasonable to assume that there must be additional very compelling reasonable to assume that there must be additional, very
evidence of need before it will be registered in the IANA registry compelling evidence of need before it will be registered in the
(to the extent that it is very unlikely that any subtags will be IANA registry (to the extent that it is very unlikely that any
registered of this type). subtags will be registered of this type).
o Dialect or other divisions or variations within a language, its o Dialect or other divisions or variations within a language, its
orthography, writing system, regional or historical usage, orthography, writing system, regional or historical usage,
transliteration or other transformation, or distinguishing transliteration or other transformation, or distinguishing
variation MAY be registered as variant subtags. An example is the variation MAY be registered as variant subtags. An example is the
'rozaj' subtag (the Resian dialect of Slovenian). 'rozaj' subtag (the Resian dialect of Slovenian).
o The addition or maintenance of fields (generally of an o The addition or maintenance of fields (generally of an
informational nature) in Tag or Subtag records as described in informational nature) in Tag or Subtag records as described in
Section 3.1 and subject to the stability provisions in Section 3.1 and subject to the stability provisions in
Section 3.4. This includes descriptions; comments; deprecation Section 3.4. This includes descriptions, comments, deprecation
and preferred values for obsolete or withdrawn codes; or the and preferred values for obsolete or withdrawn codes, or the
addition of script or extlang information to primary language addition of script or extlang information to primary language
subtags. subtags.
o The addition of records and related field value changes necessary o The addition of records and related field value changes necessary
to reflect assignments made by ISO 639, ISO 15924, ISO 3166, and to reflect assignments made by ISO 639, ISO 15924, ISO 3166, and
UN M.49 as described in Section 3.4. UN M.49 as described in Section 3.4.
Subtags proposed for registration that would cause all or part of a Subtags proposed for registration that would cause all or part of a
grandfathered tag to become redundant but whose meaning conflicts grandfathered tag to become redundant but whose meaning conflicts
with or alters the meaning of the grandfathered tag MUST be rejected. with or alters the meaning of the grandfathered tag MUST be rejected.
This document leaves the decision on what subtags or changes to This document leaves the decision on what subtags or changes to
subtags are appropriate (or not) to the registration process subtags are appropriate (or not) to the registration process
described in Section 3.5. described in Section 3.5.
Note: four character primary language subtags are reserved to allow Note: four-character primary language subtags are reserved to allow
for the possibility of alpha4 codes in some future addition to the for the possibility of alpha4 codes in some future addition to the
ISO 639 family of standards. ISO 639 family of standards.
ISO 639 defines a maintenance agency for additions to and changes in ISO 639 defines a maintenance agency for additions to and changes in
the list of languages in ISO 639. This agency is: the list of languages in ISO 639. This agency is:
International Information Centre for Terminology (Infoterm) International Information Centre for Terminology (Infoterm)
Aichholzgasse 6/12, AT-1120 Aichholzgasse 6/12, AT-1120
Wien, Austria 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 ISO 639-2 defines a maintenance agency for additions to and changes
in the list of languages in ISO 639-2. This agency is: in the list of languages in ISO 639-2. This agency is:
Library of Congress Library of Congress
Network Development and MARC Standards Office Network Development and MARC Standards Office
Washington, D.C. 20540 USA Washington, D.C. 20540 USA
Phone: +1 202 707 6237 Fax: +1 202 707 0115 Phone: +1 202 707 6237 Fax: +1 202 707 0115
URL: http://www.loc.gov/standards/iso639 URL: http://www.loc.gov/standards/iso639-2
The maintenance agency for ISO 3166 (country codes) is: The maintenance agency for ISO 3166 (country codes) is:
ISO 3166 Maintenance Agency ISO 3166 Maintenance Agency
c/o International Organization for Standardization c/o International Organization for Standardization
Case postale 56 Case postale 56
CH-1211 Geneva 20 Switzerland CH-1211 Geneva 20 Switzerland
Phone: +41 22 749 72 33 Fax: +41 22 749 73 49 Phone: +41 22 749 72 33 Fax: +41 22 749 73 49
URL: http://www.iso.org/iso/en/prods-services/iso3166ma/index.html URL: http://www.iso.org/iso/en/prods-services/iso3166ma/index.html
The registration authority for ISO 15924 (script codes) is: The registration authority for ISO 15924 (script codes) is:
skipping to change at page 33, line 45 skipping to change at page 34, line 34
Statistics Division Statistics Division
United Nations, Room DC2-1620 United Nations, Room DC2-1620
New York, NY 10017, USA New York, NY 10017, USA
Fax: +1-212-963-0623 Fax: +1-212-963-0623
E-mail: statistics@un.org E-mail: statistics@un.org
URL: http://unstats.un.org/unsd/methods/m49/m49alpha.htm URL: http://unstats.un.org/unsd/methods/m49/m49alpha.htm
3.7. Extensions and Extensions Registry 3.7. Extensions and Extensions Registry
Extension subtags are those introduced by single character subtags Extension subtags are those introduced by single-character subtags
("singletons") other than 'x'. They are reserved for the generation ("singletons") other than 'x'. They are reserved for the generation
of identifiers which contain a language component, and are compatible of identifiers that contain a language component and are compatible
with applications that understand language tags. with applications that understand language tags.
The structure and form of extensions are defined by this document so The structure and form of extensions are defined by this document so
that implementations can be created that are forward compatible with that implementations can be created that are forward compatible with
applications that might be created using singletons in the future. applications that might be created using singletons in the future.
In addition, defining a mechanism for maintaining singletons will In addition, defining a mechanism for maintaining singletons will
lend stability to this document by reducing the likely need for lend stability to this document by reducing the likely need for
future revisions or updates. future revisions or updates.
Single character subtags are assigned by IANA using the "IETF Single-character subtags are assigned by IANA using the "IETF
Consensus" policy defined by [RFC2434]. This policy requires the Consensus" policy defined by [RFC2434]. This policy requires the
development of an RFC, which SHALL define the name, purpose, development of an RFC, which SHALL define the name, purpose,
processes, and procedures for maintaining the subtags. The processes, and procedures for maintaining the subtags. The
maintaining or registering authority, including name, contact email, maintaining or registering authority, including name, contact email,
discussion list email, and URL location of the registry MUST be discussion list email, and URL location of the registry, MUST be
indicated clearly in the RFC. The RFC MUST specify or include each indicated clearly in the RFC. The RFC MUST specify or include each
of the following: of the following:
o The specification MUST reference the specific version or revision o The specification MUST reference the specific version or revision
of this document that governs its creation and MUST reference this of this document that governs its creation and MUST reference this
section of this document. section of this document.
o The specification and all subtags defined by the specification o The specification and all subtags defined by the specification
MUST follow the ABNF and other rules for the formation of tags and MUST follow the ABNF and other rules for the formation of tags and
subtags as defined in this document. In particular it MUST subtags as defined in this document. In particular, it MUST
specify that case is not significant and that subtags MUST NOT specify that case is not significant and that subtags MUST NOT
exceed eight characters in length. exceed eight characters in length.
o The specification MUST specify a canonical representation. o The specification MUST specify a canonical representation.
o The specification of valid subtags MUST be available over the o The specification of valid subtags MUST be available over the
Internet and at no cost. Internet and at no cost.
o The specification MUST be in the public domain or available via a o The specification MUST be in the public domain or available via a
royalty-free license acceptable to the IETF and specified in the royalty-free license acceptable to the IETF and specified in the
RFC. RFC.
o The specification MUST be versioned and each version of the o The specification MUST be versioned, and each version of the
specification MUST be numbered, dated, and stable. specification MUST be numbered, dated, and stable.
o The specification MUST be stable. That is, extension subtags, o The specification MUST be stable. That is, extension subtags,
once defined by a specification, MUST NOT be retracted or change once defined by a specification, MUST NOT be retracted or change
in meaning in any substantial way. in meaning in any substantial way.
o The specification MUST include in a separate section the o The specification MUST include in a separate section the
registration form reproduced in this section (below) to be used in registration form reproduced in this section (below) to be used in
registering the extension upon publication as an RFC. registering the extension upon publication as an RFC.
o IANA MUST be informed of changes to the contact information and o IANA MUST be informed of changes to the contact information and
URL for the specification. URL for the specification.
IANA will maintain a registry of allocated single character IANA will maintain a registry of allocated single-character
(singleton) subtags. This registry MUST use the record-jar format (singleton) subtags. This registry MUST use the record-jar format
described by the ABNF in Section 3.1. Upon publication of an described by the ABNF in Section 3.1. Upon publication of an
extension as an RFC, the maintaining authority defined in the RFC extension as an RFC, the maintaining authority defined in the RFC
MUST forward this registration form to iesg@ietf.org, who MUST MUST forward this registration form to iesg@ietf.org, who MUST
forward the request to iana@iana.org. The maintaining authority of forward the request to iana@iana.org. The maintaining authority of
the extension MUST maintain the accuracy of the record by sending an the extension MUST maintain the accuracy of the record by sending an
updated full copy of the record to iana@iana.org with the subject updated full copy of the record to iana@iana.org with the subject
line "LANGUAGE TAG EXTENSION UPDATE" whenever content changes. Only line "LANGUAGE TAG EXTENSION UPDATE" whenever content changes. Only
the 'Comments', 'Contact_Email', 'Mailing_List', and 'URL' fields MAY the 'Comments', 'Contact_Email', 'Mailing_List', and 'URL' fields MAY
be modified in these updates. be modified in these updates.
Failure to maintain this record, the corresponding registry, or meet Failure to maintain this record, maintain the corresponding registry,
other conditions imposed by this section of this document MAY be or meet other conditions imposed by this section of this document MAY
appealed to the IESG [RFC2028] under the same rules as other IETF be appealed to the IESG [RFC2028] under the same rules as other IETF
decisions (see [RFC2026]) and MAY result in the authority to maintain decisions (see [RFC2026]) and MAY result in the authority to maintain
the extension being withdrawn or reassigned by the IESG. the extension being withdrawn or reassigned by the IESG.
%% %%
Identifier: Identifier:
Description: Description:
Comments: Comments:
Added: Added:
RFC: RFC:
Authority: Authority:
Contact_Email: Contact_Email:
Mailing_List: Mailing_List:
URL: URL:
skipping to change at page 35, line 34 skipping to change at page 36, line 25
Added: Added:
RFC: RFC:
Authority: Authority:
Contact_Email: Contact_Email:
Mailing_List: Mailing_List:
URL: URL:
%% %%
Figure 6: Format of Records in the Language Tag Extensions Registry Figure 6: Format of Records in the Language Tag Extensions Registry
'Identifier' contains the single character subtag (singleton) 'Identifier' contains the single-character subtag (singleton)
assigned to the extension. The Internet-Draft submitted to define assigned to the extension. The Internet-Draft submitted to define
the extension SHOULD specify which letter or digit to use, although the extension SHOULD specify which letter or digit to use, although
the IESG MAY change the assignment when approving the RFC. the IESG MAY change the assignment when approving the RFC.
'Description' contains the name and description of the extension. 'Description' contains the name and description of the extension.
'Comments' is an OPTIONAL field and MAY contain a broader description 'Comments' is an OPTIONAL field and MAY contain a broader description
of the extension. of the extension.
'Added' contains the date the RFC was published in the "full-date" 'Added' contains the date the RFC was published in the "full-date"
skipping to change at page 36, line 15 skipping to change at page 37, line 7
'Contact_Email' contains the email address used to contact the 'Contact_Email' contains the email address used to contact the
maintaining authority. maintaining authority.
'Mailing_List' contains the URL or subscription email address of the 'Mailing_List' contains the URL or subscription email address of the
mailing list used by the maintaining authority. mailing list used by the maintaining authority.
'URL' contains the URL of the registry for this extension. 'URL' contains the URL of the registry for this extension.
The determination of whether an Internet-Draft meets the above The determination of whether an Internet-Draft meets the above
conditions and the decision to grant or withhold such authority rests conditions and the decision to grant or withhold such authority rests
solely with the IESG, and is subject to the normal review and appeals solely with the IESG and is subject to the normal review and appeals
process associated with the RFC process. process associated with the RFC process.
Extension authors are strongly cautioned that many (including most Extension authors are strongly cautioned that many (including most
well-formed) processors will be unaware of any special relationships well-formed) processors will be unaware of any special relationships
or meaning inherent in the order of extension subtags. Extension or meaning inherent in the order of extension subtags. Extension
authors SHOULD avoid subtag relationships or canonicalization authors SHOULD avoid subtag relationships or canonicalization
mechanisms that interfere with matching or with length restrictions mechanisms that interfere with matching or with length restrictions
that sometimes exist in common protocols where the extension is used. that sometimes exist in common protocols where the extension is used.
In particular, applications MAY truncate the subtags in doing In particular, applications MAY truncate the subtags in doing
matching or in fitting into limited lengths, so it is RECOMMENDED matching or in fitting into limited lengths, so it is RECOMMENDED
that the most significant information be in the most significant that the most significant information be in the most significant
(left-most) subtags, and that the specification gracefully handle (left-most) subtags and that the specification gracefully handle
truncated subtags. truncated subtags.
When a language tag is to be used in a specific, known, protocol, it When a language tag is to be used in a specific, known, protocol, it
is RECOMMENDED that that the language tag not contain extensions not is RECOMMENDED that the language tag not contain extensions not
supported by that protocol. In addition, note that some protocols supported by that protocol. In addition, note that some protocols
MAY impose upper limits on the length of the strings used to store or MAY impose upper limits on the length of the strings used to store or
transport the language tag. transport the language tag.
3.8. Initialization of the Registries 3.8. Initialization of the Registries
Upon adoption of this document an initial version of the Language Upon adoption of this document, an initial version of the Language
Subtag Registry containing the various subtags initially valid in a Subtag Registry containing the various subtags initially valid in a
language tag is necessary. This collection of subtags, along with a language tag is necessary. This collection of subtags, along with a
description of the process used to create it, is described by description of the process used to create it, is described by
[initial-registry]. IANA SHALL publish the initial version of the [RFC4645]. IANA SHALL publish the initial version of the registry
registry described by this document from the content of [initial- described by this document from the content of [RFC4645]. Once
registry]. Once published by IANA, the maintenance procedures, rules published by IANA, the maintenance procedures, rules, and
and registration processes described in this document will be registration processes described in this document will be available
available for new registrations or updates. for new registrations or updates.
Registrations that are in process under the rules defined in Registrations that are in process under the rules defined in
[RFC3066] when this document is adopted MAY be completed under the [RFC3066] when this document is adopted MAY be completed under the
former rules, at the discretion of the Language Tag Reviewer (as former rules, at the discretion of the Language Tag Reviewer (as
described in [RFC3066]). Until the IESG officially appoints a described in [RFC3066]). Until the IESG officially appoints a
Language Subtag Reviewer, the existing Language Tag Reviewer SHALL Language Subtag Reviewer, the existing Language Tag Reviewer SHALL
serve as the Language Subtag Reviewer. serve as the Language Subtag Reviewer.
Any new registrations submitted using the RFC 3066 forms or format Any new registrations submitted using the RFC 3066 forms or format
after the adoption of this document and publication of the registry after the adoption of this document and publication of the registry
by IANA MUST be rejected. by IANA MUST be rejected.
An initial version of the Language Extension Registry described in An initial version of the Language Tag Extensions Registry described
Section 3.7 is also needed. The Language Extension Registry SHALL be in Section 3.7 is also needed. The Language Tag Extensions Registry
initialized with a single record containing a single field of type SHALL be initialized with a single record containing a single field
"File-Date" as a placeholder for future assignments. of type "File-Date" as a placeholder for future assignments.
4. Formation and Processing of Language Tags 4. Formation and Processing of Language Tags
This section addresses how to use the information in the registry This section addresses how to use the information in the registry
with the tag syntax to choose, form and process language tags. with the tag syntax to choose, form, and process language tags.
4.1. Choice of Language Tag 4.1. Choice of Language Tag
One is sometimes faced with the choice between several possible tags One is sometimes faced with the choice between several possible tags
for the same body of text. for the same body of text.
Interoperability is best served when all users use the same language Interoperability is best served when all users use the same language
tag in order to represent the same language. If an application has tag in order to represent the same language. If an application has
requirements that make the rules here inapplicable, then that requirements that make the rules here inapplicable, then that
application risks damaging interoperability. It is strongly application risks damaging interoperability. It is strongly
skipping to change at page 38, line 38 skipping to change at page 38, line 43
be used in a language tag. be used in a language tag.
Of particular note, many applications can benefit from the use of Of particular note, many applications can benefit from the use of
script subtags in language tags, as long as the use is consistent for script subtags in language tags, as long as the use is consistent for
a given context. Script subtags were not formally defined in RFC a given context. Script subtags were not formally defined in RFC
3066 and their use can affect matching and subtag identification by 3066 and their use can affect matching and subtag identification by
implementations of RFC 3066, as these subtags appear between the implementations of RFC 3066, as these subtags appear between the
primary language and region subtags. For example, if a user requests primary language and region subtags. For example, if a user requests
content in an implementation of Section 2.5 of [RFC3066] using the content in an implementation of Section 2.5 of [RFC3066] using the
language range "en-US", content labeled "en-Latn-US" will not match language range "en-US", content labeled "en-Latn-US" will not match
the request. Therefore it is important to know when script subtags the request. Therefore, it is important to know when script subtags
will customarily be used and when they ought not be used. In the will customarily be used and when they ought not be used. In the
registry, the Suppress-Script field helps ensure greater registry, the Suppress-Script field helps ensure greater
compatibility between the language tags generated according to the compatibility between the language tags generated according to the
rules in this document and language tags and tag processors or rules in this document and language tags and tag processors or
consumers based on RFC 3066 by defining when users SHOULD NOT include consumers based on RFC 3066 by defining when users SHOULD NOT include
a script subtag with a particular primary language subtag. a script subtag with a particular primary language subtag.
Extended language subtags (type 'extlang' in the registry, see Extended language subtags (type 'extlang' in the registry; see
Section 3.1) also appear between the primary language and region Section 3.1) also appear between the primary language and region
subtags and are reserved for future standardization. Applications subtags and are reserved for future standardization. Applications
might benefit from their judicious use in forming language tags in might benefit from their judicious use in forming language tags in
the future. Similar recommendations are expected to apply to their the future. Similar recommendations are expected to apply to their
use as apply to script subtags. use as apply to script subtags.
Standards, protocols and applications that reference this document Standards, protocols, and applications that reference this document
normatively but apply different rules to the ones given in this normatively but apply different rules to the ones given in this
section MUST specify how the procedure varies from the one given section MUST specify how the procedure varies from the one given
here. here.
The choice of subtags used to form a language tag SHOULD be guided by The choice of subtags used to form a language tag SHOULD be guided by
the following rules: the following rules:
1. Use as precise a tag as possible, but no more specific than is 1. Use as precise a tag as possible, but no more specific than is
justified. Avoid using subtags that are not important for justified. Avoid using subtags that are not important for
distinguishing content in an application. distinguishing content in an application.
skipping to change at page 40, line 38 skipping to change at page 40, line 49
might be interpreted as the set of languages that is necessary for might be interpreted as the set of languages that is necessary for
a complete comprehension of the complete object. Example: Plain a complete comprehension of the complete object. Example: Plain
text documents. text documents.
o For an aggregation of information objects, the associated language o For an aggregation of information objects, the associated language
tags could be taken as the set of languages used inside components tags could be taken as the set of languages used inside components
of that aggregation. Examples: Document stores and libraries. of that aggregation. Examples: Document stores and libraries.
o For information objects whose purpose is to provide alternatives, o For information objects whose purpose is to provide alternatives,
the associated language tags could be regarded as a hint that the the associated language tags could be regarded as a hint that the
content is provided in several languages, and that one has to content is provided in several languages and that one has to
inspect each of the alternatives in order to find its language or inspect each of the alternatives in order to find its language or
languages. In this case, the presence of multiple tags might not languages. In this case, the presence of multiple tags might not
mean that one needs to be multi-lingual to get complete mean that one needs to be multi-lingual to get complete
understanding of the document. Example: MIME multipart/ understanding of the document. Example: MIME multipart/
alternative. alternative.
o In markup languages, such as HTML and XML, language information o In markup languages, such as HTML and XML, language information
can be added to each part of the document identified by the markup can be added to each part of the document identified by the markup
structure (including the whole document itself). For example, one structure (including the whole document itself). For example, one
could write <span lang="fr">C'est la vie.</span> inside a could write <span lang="fr">C'est la vie.</span> inside a
skipping to change at page 41, line 12 skipping to change at page 41, line 22
a French-Norwegian dictionary to find out what the marked section a French-Norwegian dictionary to find out what the marked section
meant. If the user were listening to that document through a meant. If the user were listening to that document through a
speech synthesis interface, this formation could be used to signal speech synthesis interface, this formation could be used to signal
the synthesizer to appropriately apply French text-to-speech the synthesizer to appropriately apply French text-to-speech
pronunciation rules to that span of text, instead of applying the pronunciation rules to that span of text, instead of applying the
inappropriate Norwegian rules. inappropriate Norwegian rules.
Language tags are related when they contain a similar sequence of Language tags are related when they contain a similar sequence of
subtags. For example, if a language tag B contains language tag A as subtags. For example, if a language tag B contains language tag A as
a prefix, then B is typically "narrower" or "more specific" than A. a prefix, then B is typically "narrower" or "more specific" than A.
Thus "zh-Hant-TW" is more specific than "zh-Hant". Thus, "zh-Hant-TW" is more specific than "zh-Hant".
This relationship is not guaranteed in all cases: specifically, This relationship is not guaranteed in all cases: specifically,
languages that begin with the same sequence of subtags are NOT languages that begin with the same sequence of subtags are NOT
guaranteed to be mutually intelligible, although they might be. For guaranteed to be mutually intelligible, although they might be. For
example, the tag "az" shares a prefix with both "az-Latn" example, the tag "az" shares a prefix with both "az-Latn"
(Azerbaijani written using the Latin script) and "az-Cyrl" (Azerbaijani written using the Latin script) and "az-Cyrl"
(Azerbaijani written using the Cyrillic script). A person fluent in (Azerbaijani written using the Cyrillic script). A person fluent in
one script might not be able to read the other, even though the text one script might not be able to read the other, even though the text
might be identical. Content tagged as "az" most probably is written might be identical. Content tagged as "az" most probably is written
in just one script and thus might not be intelligible to a reader in just one script and thus might not be intelligible to a reader
skipping to change at page 41, line 40 skipping to change at page 41, line 50
region subtags with a combined total length of up to six characters, region subtags with a combined total length of up to six characters,
larger registered tags were not only possible but were actually larger registered tags were not only possible but were actually
registered. registered.
Neither the language tag syntax nor other requirements in this Neither the language tag syntax nor other requirements in this
document impose a fixed upper limit on the number of subtags in a document impose a fixed upper limit on the number of subtags in a
language tag (and thus an upper bound on the size of a tag). The language tag (and thus an upper bound on the size of a tag). The
language tag syntax suggests that, depending on the specific language tag syntax suggests that, depending on the specific
language, more subtags (and thus a longer tag) are sometimes language, more subtags (and thus a longer tag) are sometimes
necessary to completely identify the language for certain necessary to completely identify the language for certain
applications; thus it is possible to envision long or complex subtag applications; thus, it is possible to envision long or complex subtag
sequences. sequences.
4.3.1. Working with Limited Buffer Sizes 4.3.1. Working with Limited Buffer Sizes
Some applications and protocols are forced to allocate fixed buffer Some applications and protocols are forced to allocate fixed buffer
sizes or otherwise limit the length of a language tag. A conformant sizes or otherwise limit the length of a language tag. A conformant
implementation or specification MAY refuse to support the storage of implementation or specification MAY refuse to support the storage of
language tags which exceed a specified length. Any such limitation language tags that exceed a specified length. Any such limitation
SHOULD be clearly documented, and such documentation SHOULD include SHOULD be clearly documented, and such documentation SHOULD include
what happens to longer tags (for example, whether an error value is what happens to longer tags (for example, whether an error value is
generated or the language tag is truncated). A protocol that allows generated or the language tag is truncated). A protocol that allows
tags to be truncated at an arbitrary limit, without giving any tags to be truncated at an arbitrary limit, without giving any
indication of what that limit is, has the potential for causing harm indication of what that limit is, has the potential for causing harm
by changing the meaning of tags in substantial ways. by changing the meaning of tags in substantial ways.
In practice, most language tags do not require more than a few In practice, most language tags do not require more than a few
subtags and will not approach reasonably sized buffer limitations: subtags and will not approach reasonably sized buffer limitations;
see Section 4.1. see Section 4.1.
Some specifications or protocols have limits on tag length but do not Some specifications or protocols have limits on tag length but do not
have a fixed length limitation. For example, [RFC2231] has no have a fixed length limitation. For example, [RFC2231] has no
explicit length limitation: the length available for the language tag explicit length limitation: the length available for the language tag
is constrained by the length of other header components (such as the is constrained by the length of other header components (such as the
charset's name) coupled with the 76 character limit in [RFC2047]. charset's name) coupled with the 76-character limit in [RFC2047].
Thus the "limit" might be 50 or more characters, but it could Thus, the "limit" might be 50 or more characters, but it could
potentially be quite small. potentially be quite small.
The considerations for assigning a buffer limit are: The considerations for assigning a buffer limit are:
Implementations SHOULD NOT truncate language tags unless the Implementations SHOULD NOT truncate language tags unless the
meaning of the tag is purposefully being changed, or unless the meaning of the tag is purposefully being changed, or unless the
tag does not fit into a limited buffer size specified by a tag does not fit into a limited buffer size specified by a
protocol for storage or transmission. protocol for storage or transmission.
Implementations SHOULD warn the user when a tag is truncated since Implementations SHOULD warn the user when a tag is truncated since
skipping to change at page 43, line 26 skipping to change at page 43, line 32
Figure 7: Derivation of the Limit on Tag Length Figure 7: Derivation of the Limit on Tag Length
4.3.2. Truncation of Language Tags 4.3.2. Truncation of Language Tags
Truncation of a language tag alters the meaning of the tag, and thus Truncation of a language tag alters the meaning of the tag, and thus
SHOULD be avoided. However, truncation of language tags is sometimes SHOULD be avoided. However, truncation of language tags is sometimes
necessary due to limited buffer sizes. Such truncation MUST NOT necessary due to limited buffer sizes. Such truncation MUST NOT
permit a subtag to be chopped off in the middle or the formation of permit a subtag to be chopped off in the middle or the formation of
invalid tags (for example, one ending with the "-" character). invalid tags (for example, one ending with the "-" character).
This means that applications or protocols which truncate tags MUST do This means that applications or protocols that truncate tags MUST do
so by progressively removing subtags along with their preceding "-" so by progressively removing subtags along with their preceding "-"
from the right side of the language tag until the tag is short enough from the right side of the language tag until the tag is short enough
for the given buffer. If the resulting tag ends with a single- for the given buffer. If the resulting tag ends with a single-
character subtag, that subtag and its preceding "-" MUST also be character subtag, that subtag and its preceding "-" MUST also be
removed. For example: removed. For example:
Tag to truncate: zh-Hant-CN-variant1-a-extend1-x-wadegile-private1 Tag to truncate: zh-Latn-CN-variant1-a-extend1-x-wadegile-private1
1. zh-Latn-CN-variant1-a-extend1-x-wadegile 1. zh-Latn-CN-variant1-a-extend1-x-wadegile
2. zh-Latn-CN-variant1-a-extend1 2. zh-Latn-CN-variant1-a-extend1
3. zh-Latn-CN-variant1 3. zh-Latn-CN-variant1
4. zh-Latn-CN 4. zh-Latn-CN
5. zh-Latn 5. zh-Latn
6. zh 6. zh
Figure 8: Example of Tag Truncation Figure 8: Example of Tag Truncation
4.4. Canonicalization of Language Tags 4.4. Canonicalization of Language Tags
skipping to change at page 44, line 7 skipping to change at page 44, line 18
language tags SHOULD always be created or generated in a canonical language tags SHOULD always be created or generated in a canonical
form. form.
A language tag is in canonical form when: A language tag is in canonical form when:
1. The tag is well-formed according the rules in Section 2.1 and 1. The tag is well-formed according the rules in Section 2.1 and
Section 2.2. Section 2.2.
2. Subtags of type 'Region' that have a Preferred-Value mapping in 2. Subtags of type 'Region' that have a Preferred-Value mapping in
the IANA registry (see Section 3.1) SHOULD be replaced with their the IANA registry (see Section 3.1) SHOULD be replaced with their
mapped value. Note: In rare cases the mapped value will also mapped value. Note: In rare cases, the mapped value will also
have a Preferred-Value. have a Preferred-Value.
3. Redundant or grandfathered tags that have a Preferred-Value 3. Redundant or grandfathered tags that have a Preferred-Value
mapping in the IANA registry (see Section 3.1) MUST be replaced mapping in the IANA registry (see Section 3.1) MUST be replaced
with their mapped value. These items are either deprecated with their mapped value. These items either are deprecated
mappings created before the adoption of this document (such as mappings created before the adoption of this document (such as
the mapping of "no-nyn" to "nn" or "i-klingon" to "tlh") or are the mapping of "no-nyn" to "nn" or "i-klingon" to "tlh") or are
the result of later registrations or additions to this document the result of later registrations or additions to this document
(for example, "zh-guoyu" might be mapped to a language-extlang (for example, "zh-guoyu" might be mapped to a language-extlang
combination such as "zh-cmn" by some future update of this combination such as "zh-cmn" by some future update of this
document). document).
4. Other subtags that have a Preferred-Value mapping in the IANA 4. Other subtags that have a Preferred-Value mapping in the IANA
registry (see Section 3.1) MUST be replaced with their mapped registry (see Section 3.1) MUST be replaced with their mapped
value. These items consist entirely of clerical corrections to value. These items consist entirely of clerical corrections to
skipping to change at page 45, line 24 skipping to change at page 45, line 35
an accompanying 'Preferred-Value' field, then that tag or subtag is an accompanying 'Preferred-Value' field, then that tag or subtag is
deprecated without a replacement. Validating processors SHOULD NOT deprecated without a replacement. Validating processors SHOULD NOT
generate tags that include these values, although the values are generate tags that include these values, although the values are
canonical when they appear in a language tag. canonical when they appear in a language tag.
An extension MUST define any relationships that exist between the An extension MUST define any relationships that exist between the
various subtags in the extension and thus MAY define an alternate various subtags in the extension and thus MAY define an alternate
canonicalization scheme for the extension's subtags. Extensions MAY canonicalization scheme for the extension's subtags. Extensions MAY
define how the order of the extension's subtags are interpreted. For define how the order of the extension's subtags are interpreted. For
example, an extension could define that its subtags are in canonical example, an extension could define that its subtags are in canonical
order when the subtags are placed into ASCII order: that is, "en-a- order when the subtags are placed into ASCII order: that is,
aaa-bbb-ccc" instead of "en-a-ccc-bbb-aaa". Another extension might "en-a-aaa-bbb-ccc" instead of "en-a-ccc-bbb-aaa". Another extension
define that the order of the subtags influences their semantic might define that the order of the subtags influences their semantic
meaning (so that "en-b-ccc-bbb-aaa" has a different value from "en-b- meaning (so that "en-b-ccc-bbb-aaa" has a different value from
aaa-bbb-ccc"). However, extension specifications SHOULD be designed "en-b-aaa-bbb-ccc"). However, extension specifications SHOULD be
so that they are tolerant of the typical processes described in designed so that they are tolerant of the typical processes described
Section 3.7. in Section 3.7.
4.5. Considerations for Private Use Subtags 4.5. Considerations for Private Use Subtags
Private use subtags, like all other subtags, MUST conform to the Private use subtags, like all other subtags, MUST conform to the
format and content constraints in the ABNF. Private use subtags have format and content constraints in the ABNF. Private use subtags have
no meaning outside the private agreement between the parties that no meaning outside the private agreement between the parties that
intend to use or exchange language tags that employ them. The same intend to use or exchange language tags that employ them. The same
subtags MAY be used with a different meaning under a separate private subtags MAY be used with a different meaning under a separate private
agreement. They SHOULD NOT be used where alternatives exist and agreement. They SHOULD NOT be used where alternatives exist and
SHOULD NOT be used in content or protocols intended for general use. SHOULD NOT be used in content or protocols intended for general use.
Private use subtags are simply useless for information exchange Private use subtags are simply useless for information exchange
without prior arrangement. The value and semantic meaning of private without prior arrangement. The value and semantic meaning of private
use tags and of the subtags used within such a language tag are not use tags and of the subtags used within such a language tag are not
defined by this document. defined by this document.
Subtags defined in the IANA registry as having a specific private use Subtags defined in the IANA registry as having a specific private use
meaning convey more information that a purely private use tag meaning convey more information that a purely private use tag
prefixed by the singleton subtag 'x'. For applications this prefixed by the singleton subtag 'x'. For applications, this
additional information MAY be useful. additional information MAY be useful.
For example, the region subtags 'AA', 'ZZ' and in the ranges For example, the region subtags 'AA', 'ZZ', and in the ranges
'QM'-'QZ' and 'XA'-'XZ' (derived from ISO 3166 private use codes) MAY 'QM'-'QZ' and 'XA'-'XZ' (derived from ISO 3166 private use codes) MAY
be used to form a language tag. A tag such as "zh-Hans-XQ" conveys a be used to form a language tag. A tag such as "zh-Hans-XQ" conveys a
great deal of public, interchangeable information about the language great deal of public, interchangeable information about the language
material (that it is Chinese in the simplified Chinese script and is material (that it is Chinese in the simplified Chinese script and is
suitable for some geographic region 'XQ'). While the precise suitable for some geographic region 'XQ'). While the precise
geographic region is not known outside of private agreement, the tag geographic region is not known outside of private agreement, the tag
conveys far more information than an opaque tag such as "x-someLang", conveys far more information than an opaque tag such as "x-someLang",
which contains no information about the language subtag or script which contains no information about the language subtag or script
subtag outside of the private agreement. subtag outside of the private agreement.
skipping to change at page 47, line 19 skipping to change at page 46, line 46
defined by this document and in accordance with the requirements of defined by this document and in accordance with the requirements of
[RFC2434]. [RFC2434].
The impact on the IANA maintainers of the two registries defined by The impact on the IANA maintainers of the two registries defined by
this document will be a small increase in the frequency of new this document will be a small increase in the frequency of new
entries or updates. entries or updates.
5.1. Language Subtag Registry 5.1. Language Subtag Registry
Upon adoption of this document, the registry will be initialized by a Upon adoption of this document, the registry will be initialized by a
companion document: [initial-registry]. The criteria and process for companion document: [RFC4645]. The criteria and process for
selecting the initial set of records is described in that document. selecting the initial set of records are described in that document.
The initial set of records represents no impact on IANA, since the The initial set of records represents no impact on IANA, since the
work to create it will be performed externally. work to create it will be performed externally.
The new registry MUST be listed under "Language Tags" at The new registry MUST be listed under "Language Tags" at
<http://www.iana.org/numbers.html>, replacing the existing <http://www.iana.org/numbers.html>, replacing the existing
registrations defined by [RFC3066]. The existing set of registration registrations defined by [RFC3066]. The existing set of registration
forms and RFC 3066 registrations MUST be relabeled as "Language Tags forms and RFC 3066 registrations MUST be relabeled as "Language Tags
(Obsolete)" and maintained (but not added to or modified). (Obsolete)" and maintained (but not added to or modified).
Future work on the Language Subtag Registry SHALL be limited to Future work on the Language Subtag Registry SHALL be limited to
skipping to change at page 48, line 7 skipping to change at page 47, line 36
MUST overwrite the record they replace. MUST overwrite the record they replace.
Included in any request to insert or modify records MUST be a new Included in any request to insert or modify records MUST be a new
File-Date record. This record MUST be placed first in the registry. File-Date record. This record MUST be placed first in the registry.
In the event that the File-Date record present in the registry has a In the event that the File-Date record present in the registry has a
later date than the record being inserted or modified, the existing later date than the record being inserted or modified, the existing
record MUST be preserved. record MUST be preserved.
5.2. Extensions Registry 5.2. Extensions Registry
The Language Tag Extensions registry will also be generated and sent The Language Tag Extensions Registry will also be generated and sent
to IANA as described in Section 3.7. This registry can contain at to IANA as described in Section 3.7. This registry can contain at
most 35 records and thus changes to this registry are expected to be most 35 records, and thus changes to this registry are expected to be
very infrequent. very infrequent.
Future work by IANA on the Language Tag Extensions Registry is Future work by IANA on the Language Tag Extensions Registry is
limited to two cases. First, the IESG MAY request that new records limited to two cases. First, the IESG MAY request that new records
be inserted into this registry from time to time. These requests be inserted into this registry from time to time. These requests
MUST include the record to insert in the exact format described in MUST include the record to insert in the exact format described in
Section 3.7. In addition, there MAY be occasional requests from the Section 3.7. In addition, there MAY be occasional requests from the
maintaining authority for a specific extension to update the contact maintaining authority for a specific extension to update the contact
information or URLs in the record. These requests MUST include the information or URLs in the record. These requests MUST include the
complete, updated record. IANA is not responsible for validating the complete, updated record. IANA is not responsible for validating the
skipping to change at page 49, line 35 skipping to change at page 48, line 35
assurance whatsoever that it does not contain characters from scripts assurance whatsoever that it does not contain characters from scripts
other than the one(s) associated with or specified by that language other than the one(s) associated with or specified by that language
tag. tag.
Since there is no limit to the number of variant, private use, and Since there is no limit to the number of variant, private use, and
extension subtags, and consequently no limit on the possible length extension subtags, and consequently no limit on the possible length
of a tag, implementations need to guard against buffer overflow of a tag, implementations need to guard against buffer overflow
attacks. See Section 4.3 for details on language tag truncation, attacks. See Section 4.3 for details on language tag truncation,
which can occur as a consequence of defenses against buffer overflow. which can occur as a consequence of defenses against buffer overflow.
Although the specification of valid subtags for an extension (see: Although the specification of valid subtags for an extension (see
Section 3.7) MUST be available over the Internet, implementations Section 3.7) MUST be available over the Internet, implementations
SHOULD NOT mechanically depend on it being always accessible, to SHOULD NOT mechanically depend on it being always accessible, to
prevent denial-of-service attacks. prevent denial-of-service attacks.
7. Character Set Considerations 7. Character Set Considerations
The syntax in this document requires that language tags use only the The syntax in this document requires that language tags use only the
characters A-Z, a-z, 0-9, and HYPHEN-MINUS, which are present in most characters A-Z, a-z, 0-9, and HYPHEN-MINUS, which are present in most
character sets, so the composition of language tags should not have character sets, so the composition of language tags should not have
any character set issues. any character set issues.
Rendering of characters based on the content of a language tag is not Rendering of characters based on the content of a language tag is not
addressed in this memo. Historically, some languages have relied on addressed in this memo. Historically, some languages have relied on
the use of specific character sets or other information in order to the use of specific character sets or other information in order to
infer how a specific character should be rendered (notably this infer how a specific character should be rendered (notably this
applies to language and culture specific variations of Han ideographs applies to language- and culture-specific variations of Han
as used in Japanese, Chinese, and Korean). When language tags are ideographs as used in Japanese, Chinese, and Korean). When language
applied to spans of text, rendering engines sometimes use that tags are applied to spans of text, rendering engines sometimes use
information in deciding which font to use in the absence of other that information in deciding which font to use in the absence of
information, particularly where languages with distinct writing other information, particularly where languages with distinct writing
traditions use the same characters. traditions use the same characters.
8. Changes from RFC 3066 8. Changes from RFC 3066
The main goals for this revision of language tags were the following: The main goals for this revision of language tags were the following:
*Compatibility.* All RFC 3066 language tags (including those in the *Compatibility.* All RFC 3066 language tags (including those in the
IANA registry) remain valid in this specification. The changes in IANA registry) remain valid in this specification. The changes in
this document represent additional constraints on language tags. this document represent additional constraints on language tags.
That is, in no case is the syntax more permissive and processors That is, in no case is the syntax more permissive and processors
skipping to change at page 52, line 26 skipping to change at page 50, line 32
in a particular script, but can deal with the minor regional in a particular script, but can deal with the minor regional
differences, can therefore select appropriate content. Applications differences, can therefore select appropriate content. Applications
that do not deal with written content will continue to omit these that do not deal with written content will continue to omit these
subtags. subtags.
*Extensibility.* Because of the widespread use of language tags, it *Extensibility.* Because of the widespread use of language tags, it
is disruptive to have periodic revisions of the core specification, is disruptive to have periodic revisions of the core specification,
even in the face of demonstrated need. The extension mechanism even in the face of demonstrated need. The extension mechanism
provides for a way for independent RFCs to define extensions to provides for a way for independent RFCs to define extensions to
language tags. These extensions have a very constrained, well- language tags. These extensions have a very constrained, well-
defined structure that prevent extensions from interfering with defined structure that prevents extensions from interfering with
implementations of language tags defined in this document. implementations of language tags defined in this document.
The document also anticipates features of ISO 639-3 with the addition The document also anticipates features of ISO 639-3 with the addition
of the extended language subtags, as well as the possibility of other of the extended language subtags, as well as the possibility of other
ISO 639 parts becoming useful for the formation of language tags in ISO 639 parts becoming useful for the formation of language tags in
the future. the future.
The use and definition of private use tags has also been modified, to The use and definition of private use tags have also been modified,
allow people to use private use subtags to extend or modify defined to allow people to use private use subtags to extend or modify
tags and to move as much information as possible out of private use defined tags and to move as much information as possible out of
and into the regular structure. private use and into the regular structure.
The goal for each of these modifications is to reduce or eliminate The goal for each of these modifications is to reduce or eliminate
the need for future revisions of this document. the need for future revisions of this document.
The specific changes in this document to meet these goals are: The specific changes in this document to meet these goals are:
o Defines the ABNF and rules for subtags so that the category of all o Defines the ABNF and rules for subtags so that the category of all
subtags can be determined without reference to the registry. subtags can be determined without reference to the registry.
o Adds the concept of well-formed vs. validating processors, o Adds the concept of well-formed vs. validating processors,
skipping to change at page 53, line 29 skipping to change at page 51, line 38
o Adds the concept of a variant subtag and allows variants to be o Adds the concept of a variant subtag and allows variants to be
used generatively. used generatively.
o Adds the ability to use a class of UN M.49 tags for supra-national o Adds the ability to use a class of UN M.49 tags for supra-national
regions and to resolve conflicts in the assignment of ISO 3166 regions and to resolve conflicts in the assignment of ISO 3166
codes. codes.
o Defines the private use tags in ISO 639, ISO 15924, and ISO 3166 o Defines the private use tags in ISO 639, ISO 15924, and ISO 3166
as the mechanism for creating private use language, script, and as the mechanism for creating private use language, script, and
region subtags respectively. region subtags, respectively.
o Adds a well-defined extension mechanism. o Adds a well-defined extension mechanism.
o Defines an extended language subtag, possibly for use with certain o Defines an extended language subtag, possibly for use with certain
anticipated features of ISO 639-3. anticipated features of ISO 639-3.
9. References 9. References
9.1. Normative References 9.1. Normative References
[ISO10646] [ISO10646] International Organization for Standardization,
International Organization for Standardization, "ISO/IEC "ISO/IEC 10646:2003. Information technology --
10646:2003. Information technology -- Universal Multiple- Universal Multiple-Octet Coded Character Set (UCS)",
Octet Coded Character Set (UCS)", 2003. 2003.
[ISO15924] [ISO15924] International Organization for Standardization, "ISO
International Organization for Standardization, "ISO 15924:2004. Information and documentation -- Codes for
15924:2004. Information and documentation -- Codes for the the representation of names of scripts", January 2004.
representation of names of scripts", January 2004.
[ISO3166-1] [ISO3166-1] International Organization for Standardization, "ISO
International Organization for Standardization, "ISO 3166- 3166-1:1997. Codes for the representation of names of
1:1997. Codes for the representation of names of countries countries and their subdivisions -- Part 1: Country
and their subdivisions -- Part 1: Country codes", 1997. codes", 1997.
[ISO639-1] [ISO639-1] International Organization for Standardization, "ISO
International Organization for Standardization, "ISO 639- 639-1:2002. Codes for the representation of names of
1:2002. Codes for the representation of names of languages languages -- Part 1: Alpha-2 code", 2002.
-- Part 1: Alpha-2 code", 2002.
[ISO639-2] [ISO639-2] International Organization for Standardization, "ISO
International Organization for Standardization, "ISO 639- 639-2:1998. Codes for the representation of names of
2:1998. Codes for the representation of names of languages languages -- Part 2: Alpha-3 code, first edition",
-- Part 2: Alpha-3 code, first edition", 1998. 1998.
[ISO646] International Organization for Standardization, "ISO/IEC [ISO646] International Organization for Standardization,
646:1991, Information technology -- ISO 7-bit coded "ISO/IEC 646:1991, Information technology -- ISO 7-bit
character set for information interchange.", 1991. coded character set for information interchange.",
1991.
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision [RFC2026] Bradner, S., "The Internet Standards Process --
3", BCP 9, RFC 2026, October 1996. Revision 3", BCP 9, RFC 2026, October 1996.
[RFC2028] Hovey, R. and S. Bradner, "The Organizations Involved in [RFC2028] Hovey, R. and S. Bradner, "The Organizations Involved
the IETF Standards Process", BCP 11, RFC 2028, in the IETF Standards Process", BCP 11, RFC 2028,
October 1996. October 1996.
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing
IANA Considerations Section in RFCs", BCP 26, RFC 2434, an IANA Considerations Section in RFCs", BCP 26,
October 1998. RFC 2434, October 1998.
[RFC2860] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of [RFC2860] Carpenter, B., Baker, F., and M. Roberts, "Memorandum
Understanding Concerning the Technical Work of the of Understanding Concerning the Technical Work of the
Internet Assigned Numbers Authority", RFC 2860, June 2000. Internet Assigned Numbers Authority", RFC 2860,
June 2000.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: [RFC3339] Klyne, G., Ed. and C. Newman, "Date and Time on the
Timestamps", RFC 3339, July 2002. Internet: Timestamps", RFC 3339, July 2002.
[RFC4234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for
Specifications: ABNF", RFC 4234, October 2005. Syntax Specifications: ABNF", RFC 4234, October 2005.
[UN_M.49] Statistics Division, United Nations, "Standard Country or [UN_M.49] Statistics Division, United Nations, "Standard Country
Area Codes for Statistical Use", UN Standard Country or or Area Codes for Statistical Use", UN Standard
Area Codes for Statistical Use, Revision 4 (United Nations Country or Area Codes for Statistical Use, Revision 4
publication, Sales No. 98.XVII.9, June 1999. (United Nations publication, Sales No. 98.XVII.9,
June 1999.
9.2. Informative References 9.2. Informative References
[RFC1766] Alvestrand, H., "Tags for the Identification of [RFC1766] Alvestrand, H., "Tags for the Identification of
Languages", RFC 1766, March 1995. Languages", RFC 1766, March 1995.
[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions) [RFC2047] Moore, K., "MIME (Multipurpose Internet Mail
Part Three: Message Header Extensions for Non-ASCII Text", Extensions) Part Three: Message Header Extensions for
RFC 2047, November 1996. Non-ASCII Text", RFC 2047, November 1996.
[RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and
Word Extensions: Character Sets, Languages, and Encoded Word Extensions: Character Sets, Languages,
Continuations", RFC 2231, November 1997. and Continuations", RFC 2231, November 1997.
[RFC2781] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO [RFC2781] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of
10646", RFC 2781, February 2000. ISO 10646", RFC 2781, February 2000.
[RFC3066] Alvestrand, H., "Tags for the Identification of [RFC3066] Alvestrand, H., "Tags for the Identification of
Languages", BCP 47, RFC 3066, January 2001. Languages", BCP 47, RFC 3066, January 2001.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing
Text on Security Considerations", BCP 72, RFC 3552, RFC Text on Security Considerations", BCP 72,
July 2003. RFC 3552, July 2003.
[Unicode] Unicode Consortium, "The Unicode Consortium. The Unicode [RFC4645] Ewell, D., Ed., "Initial Language Subtag Registry",
Standard, Version 4.1.0, defined by: The Unicode Standard, RFC 4645, September 2006.
Version 4.0 (Boston, MA, Addison-Wesley, 2003. ISBN 0-321-
18578-1), as amended by Unicode 4.0.1
(http://www.unicode.org/versions/Unicode4.0.1) and by
Unicode 4.1.0
(http://www.unicode.org/versions/Unicode4.1.0).",
March 2005.
[XML10] Bray (et al), T., "Extensible Markup Language (XML) 1.0", [RFC4647] Phillips, A., Ed. and M. Davis, Ed., "Matching of
02 2004. Language Tags", BCP 47, RFC 4647, September 2006.
[XMLSchema] [Unicode] Unicode Consortium, "The Unicode Standard, Version
Biron, P., Ed. and A. Malhotra, Ed., "XML Schema Part 2: 5.0", Boston, MA, Addison-Wesley, 2007. ISBN 0-321-
Datatypes Second Edition", 10 2004, < 48091-0.
http://www.w3.org/TR/xmlschema-2/>.
[initial-registry] [XML10] Bray (et al), T., "Extensible Markup Language (XML)
Ewell, D., Ed., "Initial Language Subtag Registry", 1.0", 02 2004.
June 2005, <http://www.ietf.org/internet-drafts/
draft-ietf-ltru-initial-registry-00.txt>.
[iso639.principles] [XMLSchema] Biron, P., Ed. and A. Malhotra, Ed., "XML Schema Part
ISO 639 Joint Advisory Committee, "ISO 639 Joint Advisory 2: Datatypes Second Edition", 10 2004, <
Committee: Working principles for ISO 639 maintenance", http://www.w3.org/TR/xmlschema-2/>.
March 2000,
<http://www.loc.gov/standards/iso639-2/
iso639jac_n3r.html>.
[record-jar] [iso639.prin] ISO 639 Joint Advisory Committee, "ISO 639 Joint
Raymond, E., "The Art of Unix Programming", 2003, Advisory Committee: Working principles for ISO 639
maintenance", March 2000, <http://www.loc.gov/
standards/iso639-2/iso639jac_n3r.html>.
[record-jar] Raymond, E., "The Art of Unix Programming", 2003,
<urn:isbn:0-13-142901-9>. <urn:isbn:0-13-142901-9>.
Appendix A. Acknowledgements Appendix A. Acknowledgements
Any list of contributors is bound to be incomplete; please regard the Any list of contributors is bound to be incomplete; please regard the
following as only a selection from the group of people who have following as only a selection from the group of people who have
contributed to make this document what it is today. contributed to make this document what it is today.
The contributors to RFC 3066 and RFC 1766, the precursors of this The contributors to RFC 3066 and RFC 1766, the precursors of this
document, made enormous contributions directly or indirectly to this document, made enormous contributions directly or indirectly to this
skipping to change at page 60, line 10 skipping to change at page 58, line 10
en-US-u-islamCal en-US-u-islamCal
zh-CN-a-myExt-x-private zh-CN-a-myExt-x-private
en-a-myExt-b-another en-a-myExt-b-another
Some Invalid Tags: Some Invalid Tags:
de-419-DE (two region tags) de-419-DE (two region tags)
a-DE (use of a single character subtag in primary position; note a-DE (use of a single-character subtag in primary position; note
that there are a few grandfathered tags that start with "i-" that that there are a few grandfathered tags that start with "i-" that
are valid) are valid)
ar-a-aaa-b-bbb-a-ccc (two extensions with same single letter ar-a-aaa-b-bbb-a-ccc (two extensions with same single-letter
prefix) prefix)
Authors' Addresses Authors' Addresses
Addison Phillips (editor) Addison Phillips (Editor)
Quest Software Yahoo! Inc.
Email: addison.phillips@quest.com EMail: addison@inter-locale.com
URI: http://www.inter-locale.com
Mark Davis (editor) Mark Davis (Editor)
IBM Google
Email: mark.davis@us.ibm.com EMail: mark.davis@macchiato.com or mark.davis@google.com
Intellectual Property Statement Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM 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.
Intellectual Property
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
skipping to change at page 62, line 29 skipping to change at page 59, line 45
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at
ietf-ipr@ietf.org. ietf-ipr@ietf.org.
Disclaimer of Validity Acknowledgement
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM 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.
Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
 End of changes. 169 change blocks. 
421 lines changed or deleted 397 lines changed or added

This html diff was produced by rfcdiff 1.32. The latest version is available from http://www.levkowetz.com/ietf/tools/rfcdiff/