draft-ietf-ltru-registry-00.txt   draft-ietf-ltru-registry-01.txt 
Network Working Group A. Phillips, Ed. Network Working Group A. Phillips, Ed.
Internet-Draft Quest Software Internet-Draft Quest Software
Expires: September 11, 2005 M. Davis, Ed. Expires: October 28, 2005 M. Davis, Ed.
IBM IBM
March 10, 2005 April 26, 2005
Tags for Identifying Languages Tags for Identifying Languages
draft-ietf-ltru-registry-00 draft-ietf-ltru-registry-01
Status of this Memo Status of this Memo
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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. This creation of user defined extensions for private interchange. This
document obsoletes RFC 3066 (which replaced RFC 1766). document obsoletes 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
2.1.1 Length Considerations . . . . . . . . . . . . . . . . 5 2.1.1 Length Considerations . . . . . . . . . . . . . . . . 6
2.2 Language Subtag Sources and Interpretation . . . . . . . . 6 2.2 Language Subtag Sources and Interpretation . . . . . . . . 7
2.2.1 Primary Language Subtag . . . . . . . . . . . . . . . 7 2.2.1 Primary Language Subtag . . . . . . . . . . . . . . . 8
2.2.2 Extended Language Subtags . . . . . . . . . . . . . . 9 2.2.2 Extended Language Subtags . . . . . . . . . . . . . . 10
2.2.3 Script Subtag . . . . . . . . . . . . . . . . . . . . 9 2.2.3 Script Subtag . . . . . . . . . . . . . . . . . . . . 10
2.2.4 Region Subtag . . . . . . . . . . . . . . . . . . . . 10 2.2.4 Region Subtag . . . . . . . . . . . . . . . . . . . . 11
2.2.5 Variant Subtags . . . . . . . . . . . . . . . . . . . 11 2.2.5 Variant Subtags . . . . . . . . . . . . . . . . . . . 12
2.2.6 Extension Subtags . . . . . . . . . . . . . . . . . . 11 2.2.6 Extension Subtags . . . . . . . . . . . . . . . . . . 13
2.2.7 Private Use Subtags . . . . . . . . . . . . . . . . . 12 2.2.7 Private Use Subtags . . . . . . . . . . . . . . . . . 14
2.2.8 Pre-Existing RFC 3066 Registrations . . . . . . . . . 13 2.2.8 Pre-Existing RFC 3066 Registrations . . . . . . . . . 15
2.2.9 Possibilities for Registration . . . . . . . . . . . . 13 2.2.9 Classes of Conformance . . . . . . . . . . . . . . . . 15
2.2.10 Classes of Conformance . . . . . . . . . . . . . . . 14 3. Registry Format and Maintenance . . . . . . . . . . . . . . . 17
2.3 Choice of Language Tag . . . . . . . . . . . . . . . . . . 15 3.1 Format of the IANA Language Subtag Registry . . . . . . . 17
2.4 Meaning of the Language Tag . . . . . . . . . . . . . . . 16 3.2 Maintenance of the Registry . . . . . . . . . . . . . . . 21
2.4.1 Canonicalization of Language Tags . . . . . . . . . . 17 3.3 Stability of IANA Registry Entries . . . . . . . . . . . . 22
2.5 Considerations for Private Use Subtags . . . . . . . . . . 18 3.4 Registration Procedure for Subtags . . . . . . . . . . . . 25
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . 20 3.5 Possibilities for Registration . . . . . . . . . . . . . . 29
3.1 Format of the IANA Language Subtag Registry . . . . . . . 20 3.6 Extensions and Extensions Namespace . . . . . . . . . . . 30
3.2 Stability of IANA Registry Entries . . . . . . . . . . . . 24 3.7 Conversion of the RFC 3066 Language Tag Registry . . . . . 33
3.3 Registration Procedure for Subtags . . . . . . . . . . . . 27 4. Formation and Processing of Language Tags . . . . . . . . . . 36
3.4 Extensions and Extensions Namespace . . . . . . . . . . . 30 4.1 Choice of Language Tag . . . . . . . . . . . . . . . . . . 36
4. Security Considerations . . . . . . . . . . . . . . . . . . 32 4.2 Meaning of the Language Tag . . . . . . . . . . . . . . . 38
5. Character Set Considerations . . . . . . . . . . . . . . . . 33 4.3 Canonicalization of Language Tags . . . . . . . . . . . . 39
6. Changes from RFC 3066 . . . . . . . . . . . . . . . . . . . 34 4.4 Considerations for Private Use Subtags . . . . . . . . . . 40
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 36 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 38 6. Security Considerations . . . . . . . . . . . . . . . . . . . 43
A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 39 7. Character Set Considerations . . . . . . . . . . . . . . . . . 44
B. Examples of Language Tags (Informative) . . . . . . . . . . 40 8. Changes from RFC 3066 . . . . . . . . . . . . . . . . . . . . 45
C. Conversion of the RFC 3066 Language Tag Registry . . . . . . 42 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Intellectual Property and Copyright Statements . . . . . . . 44 9.1 Normative References . . . . . . . . . . . . . . . . . . . 50
9.2 Informative References . . . . . . . . . . . . . . . . . . 51
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 52
A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 53
B. Examples of Language Tags (Informative) . . . . . . . . . . . 54
C. Example Registry . . . . . . . . . . . . . . . . . . . . . . . 57
Intellectual Property and Copyright Statements . . . . . . . . 61
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.
Information about a user's language preferences commonly needs to be Information about a user's language preferences commonly needs to be
identified so that appropriate processing can be applied. For identified so that appropriate processing can be applied. For
example, the user's language preferences in a browser can be used to example, the user's language preferences in a browser can be used to
skipping to change at page 3, line 43 skipping to change at page 3, line 43
dialect, writing system, or orthography used in a document or dialect, writing system, or orthography used in a document or
resource, as these attributes may be important for the user to obtain resource, as these attributes may be important for the user to obtain
information in a form that they can understand, or important in information in a form that they can understand, or important in
selecting appropriate processing resources for the given content. selecting appropriate processing resources for the given content.
This document specifies an identifier mechanism and a registration This document specifies an identifier mechanism and a registration
function for values to be used with that identifier mechanism. It function for values to be used with that identifier mechanism. It
also defines a mechanism for private use values and future extension. also defines a mechanism for private use values and future extension.
This document replaces RFC 3066, which replaced RFC 1766. For a list This document replaces RFC 3066, which replaced RFC 1766. For a list
of changes in this document, see Section 6. 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 [RFC 2119] [11]. document are to be interpreted as described in [RFC 2119] [10].
2. The Language Tag 2. The Language Tag
2.1 Syntax 2.1 Syntax
The language tag is composed of one or more parts: A primary language The language tag is composed of one or more parts: A primary language
subtag and a (possibly empty) series of subsequent subtags. Subtags subtag and a (possibly empty) series of subsequent subtags. Subtags
are distinguished by their length, position in the subtag sequence, are distinguished by their length, position in the subtag sequence,
and content, so that each type of subtag can be recognized solely by and content, so that each type of subtag can be recognized solely by
these features. This makes it possible to construct a parser that these features. This makes it possible to construct a parser that
can extract and assign some semantic information to the subtags, even can extract and assign some semantic information to the subtags, even
if specific subtag values are not recognized. Thus a parser need not if specific subtag values are not recognized. Thus a parser need not
have an up-to-date copy of the registered subtag values to perform have an up-to-date copy of the registered subtag values to perform
most searching and matching operations. most searching and matching operations.
The syntax of this tag in ABNF [RFC 2234] [13] is: The syntax of this tag in ABNF [7] is:
Language-Tag = (lang Language-Tag = (lang
*("-" extlang) *("-" extlang)
["-" script] ["-" script]
["-" region] ["-" region]
*("-" variant) *("-" variant)
*("-" extension) *("-" extension)
["-" privateuse]) ["-" privateuse])
/ privateuse ; private-use tag / privateuse ; private-use tag
/ grandfathered ; grandfathered registrations / grandfathered ; grandfathered registrations
lang = 2*3ALPHA ; shortest ISO 639 code lang = 2*3ALPHA ; shortest ISO 639 code
/ registered-lang / registered-lang
extlang = 3ALPHA ; reserved for future use extlang = 3ALPHA ; reserved for future use
script = 4ALPHA ; ISO 15924 code script = 4ALPHA ; ISO 15924 code
region = 2ALPHA ; ISO 3166 code region = 2ALPHA ; ISO 3166 code
/ 3DIGIT ; UN country number / 3DIGIT ; UN country number
variant = ALPHA (4*7alphanum) ; registered variants variant = 5*8alphanum ; registered variants
/ DIGIT (3*7alphanum) / ( DIGIT 3alphanum )
extension = singleton 1*("-" (2*8alphanum)) ; extension subtag(s) extension = singleton 1*("-" (2*8alphanum))
privateuse = ("x"/"X") 1*("-" (1*8alphanum)) ; private use subtag(s) privateuse = ("x"/"X") 1*("-" (1*8alphanum))
singleton = ("a"-"w" / "y"-"z" / "A"-"W" / "Y"-"Z") singleton = %x41-57 / %x59-5A / %x61-77 / %x79-7A / DIGIT
; "a"-"w" / "y"-"z" / "A"-"W" / "Y"-"Z" / "0"-"9"
; Single letters: x/X is reserved for private use ; Single letters: x/X is reserved for private use
registered-lang = 4*8ALPHA ; registered language subtag registered-lang = 4*8ALPHA ; registered language subtag
grandfathered = 1*3ALPHA 1*2("-" (2*8alphanum)) ; grandfathered registration grandfathered = 1*3ALPHA 1*2("-" (2*8alphanum))
; Note: i is the only singleton that starts ; grandfathered registration
; a grandfathered tag ; Note: i is the only singleton
; that starts a grandfathered tag
alphanum = (ALPHA / DIGIT) ; letters and numbers alphanum = (ALPHA / DIGIT) ; letters and numbers
Figure 1: Language Tag ABNF Figure 1: Language Tag ABNF
The character "-" is HYPHEN-MINUS (ABNF: %x2D). Note that there is a The character "-" is HYPHEN-MINUS (ABNF: %x2D). All subtags have a
subtlety in the ABNF for 'variant': variants may consist of sequences maximum length of eight characters. Note that there is a subtlety in
of up to eight characters. the ABNF for 'variant': variants starting with a digit may be only
four characters long, while those starting with a letter must be at
least five characters long.
Whitespace is not permitted in a language tag. For examples of Whitespace is not permitted in a language tag. For examples of
language tags, see Appendix B. language tags, see Appendix B.
Note that although [RFC 2234] [13] refers to octets, the language Note that although [7] refers to octets, the language tags described
tags described in this document are sequences of characters from the in this document are sequences of characters from the US-ASCII
US-ASCII repertoire. Language tags may be used in documents and repertoire. Language tags may be used in documents and applications
applications that use other encodings, so long as these encompass the that use other encodings, so long as these encompass the US-ASCII
US-ASCII repertoire. An example of this would be an XML document repertoire. An example of this would be an XML document that uses
that uses the Unicode UTF-16LE encoding. the UTF-16LE [12] encoding of Unicode [20].
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 should not be taken capitalization of some of the subtags, but these should not be taken
to carry meaning. to carry meaning.
For example: For example:
o [ISO 639] [1] recommends that language codes be written in lower o [ISO 639] [1] recommends that language codes be written in lower
case ('mn' Mongolian). case ('mn' Mongolian).
o [ISO 3166] [4] recommends that country codes be capitalized ('MN' o [ISO 3166] [4] recommends that country codes be capitalized ('MN'
Mongolia). Mongolia).
o [ISO 15924] [3] recommends that script codes use lower case with o [ISO 15924] [3] recommends that script codes use lower case with
the initial letter capitalized ('Cyrl' Cyrillic). the initial letter capitalized ('Cyrl' Cyrillic).
However, in the tags defined by this document, the uppercase US-ASCII
letters in the range 'A' (ABNF: %x41) through 'Z' (ABNF: %x5A) are
considered equivalent and mapped directly to their US-ASCII lowercase
equivalents in the range 'a' (ABNF: %x61) through 'z' (ABNF: %x7A).
Thus the tag "mn-Cyrl-MN" is not distinct from "MN-cYRL-mn" or
"mN-cYrL-Mn" (or any other combination) and each of these variations
conveys the same meaning: Mongolian written in the Cyrillic script as
used in Mongolia.
For informative examples of language tags, see Appendix B at the end However, in the tags defined by this document, the uppercase US-ASCII
of this document. letters in the range 'A' through 'Z' are considered equivalent and
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-
cYRL-mn" or "mN-cYrL-Mn" (or any other combination) and each of these
variations conveys the same meaning: Mongolian written in the
Cyrillic script as used in Mongolia.
2.1.1 Length Considerations 2.1.1 Length Considerations
Although neither the ABNF nor other guidelines in this document Although neither the ABNF nor other guidelines in this document
provide a fixed upper limit on the number of size of subtags in a provide a fixed upper limit on the number of subtags in a Language
Language Tag and it is possible to envision quite long and complex Tag (and thus the upper bound on the size of a tag) and it is
subtag sequences, in practice these are rare because additional possible to envision quite long and complex subtag sequences, in
granularity in tags seldom adds useful distinguishing information and practice these are rare because additional granularity in tags seldom
because longer, more granular tags interefere with the meaning, adds useful distinguishing information and because longer, more
understanding, and processing of language tags. granular tags interefere with the meaning, understanding, and
processing of language tags.
In particular, variant subtags SHOULD be used only with their In particular, variant subtags SHOULD be used only with their
recommended prefix. This limits most tags to a sequence of four recommended prefix. In practice, this limits most tags to a sequence
subtags (excluding any extensions or private use sequences). See of four subtags, and thus a maximum length of 26 characters
Section 2.3 for more information on selecting the most appropriate (excluding any extensions or private use sequences). This is because
subtags are limited to a length of eight characters and the extlang,
script, and region subtags are limited to even fewer characters. See
Section 4.1 for more information on selecting the most appropriate
Language Tag. Language Tag.
A conformant implementation need not support the storage of language A conformant implementation MAY refuse to support the storage of
tags which exceed a specified length. For an example, see [RFC 2231] language tags which exceed a specified length. For an example, see
[12]. Any such a limitation MUST be clearly documented, and such [RFC 2231] [22]. Any such limitation MUST be clearly documented, and
documentation SHOULD include the disposition of any longer tags (for such documentation SHOULD include the disposition of any longer tags
example, whether an error value is generated or the language tag is (for example, whether an error value is generated or the language tag
truncated). If truncation is permitted it SHOULD NOT permit a subtag is truncated). If truncation is permitted it SHOULD NOT permit a
to be divided. subtag to be divided.
2.2 Language Subtag Sources and Interpretation 2.2 Language Subtag Sources and Interpretation
The namespace of language tags and their subtags is administered by The namespace of language tags and their subtags is administered by
the Internet Assigned Numbers Authority (IANA) [17] according to the the Internet Assigned Numbers Authority (IANA) [13] according to the
rules in Section 3 of this document. The registry maintained by IANA rules in Section 5 of this document. The registry maintained by IANA
is the source for valid subtags: other standards referenced in this is the source for valid subtags: other standards referenced in this
section provide the source material for that registry. section provide the source material for that registry.
Terminology in this section: Terminology in this section:
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, separated 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 tags 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' which are used as subtags in this document). For example, 'Latn'
is an [ISO 15924] [3] script code which was used to define the is an [ISO 15924] [3] script code which was used to define the
'Latn' script subtag for use in a language tag. Examples of codes 'Latn' script subtag for use in a language tag. Examples of codes
in this document are enclosed in single quotes ('en', 'Latn'). in 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 has unique length and Language tags are designed so that each subtag type has unique length
content restrictions. These make identification of the subtag's type and content restrictions. These make identification of the subtag's
possible, even if the content of the subtag itself is unrecognized. type possible, even if the content of the subtag itself is
This allows tags to be parsed and processed without reference to the unrecognized. This allows tags to be parsed and processed without
latest version of the underlying standards or the IANA registry and reference to the latest version of the underlying standards or the
makes the associated exception handling when parsing tags simpler. IANA registry and makes the associated exception handling when
parsing tags simpler.
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.
skipping to change at page 7, line 18 skipping to change at page 8, line 15
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 digit subtags are reserved for current or future
use. These include the following current uses: 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 3.4. Section 3.6.
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 subtag is the first subtag in a language tag and cannot The primary language subtag is the first subtag in a language tag
be empty. Except as noted, the primary subtag is the language (with the exception of private-use and certain grandfathered tags)
subtag. The following rules apply to the assignment and and cannot be omitted. The following rules apply to the primary
interpretation of the primary subtag: language subtag:
o All 2-character language subtags were defined in the IANA registry 1. All two character language subtags were defined in the IANA
according to the assignments found in the standard ISO 639 Part 1, registry according to the assignments found in the standard ISO
"ISO 639-1:2002, Codes for the representation of names of 639 Part 1, "ISO 639-1:2002, Codes for the representation of
languages -- Part 1: Alpha-2 code" [ISO 639-1] [1], or using names of languages -- Part 1: Alpha-2 code" [ISO 639-1] [1], or
assignments subsequently made by the ISO 639 Part 1 maintenance using assignments subsequently made by the ISO 639 Part 1
agency or governing standardization bodies. maintenance agency or governing standardization bodies.
o All 3-character language subtags were defined in the IANA registry
according to the assignments found in ISO 639 Part 2, "ISO 2. All three character language subtags were defined in the IANA
639-2:1998 - Codes for the representation of names of languages -- registry according to the assignments found in ISO 639 Part 2,
Part 2: Alpha-3 code - edition 1" [ISO 639-2] [2], or assignments "ISO 639-2:1998 - Codes for the representation of names of
subsequently made by the ISO 639 Part 2 maintenance agency or languages -- Part 2: Alpha-3 code - edition 1" [ISO 639-2] [2],
governing standardization bodies. or assignments subsequently made by the ISO 639 Part 2
o The subtags in the range 'qaa' through 'qtz' are reserved for maintenance agency or governing standardization bodies.
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 2.5 private-use subtags following 'x-'). Please refer to Section 4.4
for more information on private use subtags. for more information on private use subtags.
o All language subtags of 4 to 8 characters in length in the IANA 4. All four character language subtags are reserved for possible
registry were defined via the registration process in Section 3.3 future standardization.
5. All language subtags of 5 to 8 characters in length in the IANA
registry were defined via the registration process in Section 3.4
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 subtags rejected by ISO 639 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.
o 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 place in the IANA registry) unless there is a private agreement in
to do so. See Section 2.5. place to do so. See Section 4.4.
o Other values MUST NOT be assigned to the primary subtag except by
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
grandfathered tags have a primary language subtag in their first
position)
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 2-character code and Note: For languages that have both an ISO 639-1 two character code
an ISO 639-2 3-character code, only the ISO 639-1 2-character code is and an ISO 639-2 three character code, only the ISO 639-1 two
defined in the IANA registry. character code is defined in the IANA registry.
Note: For languages that have no ISO 639-1 2-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 3-character code were also assigned languages that had both kinds of three character code were also
a 2-character code; it is not expected that future assignments of assigned a two character code; it is not expected that future
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 ISO 639 Registration Authority Joint Advisory Committee (ISO 639/
639/RA-JAC) has included the following statement in [6]: RA-JAC) has included the following statement in [16]:
"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 of the canonical form of tags, if a In order to avoid instability of the canonical form of tags, if a two
2-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
3-character code was already included in ISO 639-2, the 2-character character code was already included in ISO 639-2, the two character
code will not be added as a subtag in the registry. See Section 3.2. code will not be added as a subtag in the registry. See Section 3.3.
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 2-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 2-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:
o 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.
o 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.
o There MAY be any additional number of extended language subtags.
o Extended language subtags will not be registered except by 3. There MAY be any additional number of extended language subtags.
4. Extended language subtags will not be registered except by
revision of this document. revision of this document.
o Extended language subtags MUST NOT be used to form language tags
5. Extended language subtags MUST NOT be used to form language tags
except by revision of this document. except by revision of this document.
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 "zh-gan" (registered under RFC 3066) might become a valid non-
non-grandfathered tag in which the subtag 'gan' might represent the grandfathered (that is, redundant) tag in which the subtag 'gan'
Chinese dialect 'Gan'. might represent the Chinese dialect 'Gan'.
2.2.3 Script Subtag 2.2.3 Script Subtag
The following rules apply to the script subtags: The following rules apply to the script subtags:
o All 4-character subtags were defined according to ISO 15924 1. All four character subtags were defined according to ISO 15924
[3]--"Codes for the representation of the names of scripts": [3]--"Codes for the representation of the names of scripts":
alpha-4 script codes, or subsequently assigned by the ISO 15924 alpha-4 script codes, or subsequently assigned by the ISO 15924
maintenance agency or governing standardization bodies, denoting maintenance agency or governing standardization bodies, denoting
the script or writing system used in conjunction with this the script or writing system used in conjunction with this
language. language.
o Script subtags MUST immediately follow the primary language subtag
and all extended language subtags and MUST occur before any other
type of subtag described below.
o The subtags 'Qaaa' through 'Qabx' are reserved for private use in
language tags. These subtags correspond to codes reserved by ISO
15924 for private use. These codes MAY be used for non-registered
script values. Please refer to Section 2.5 for more information
on private-use subtags.
o Script subtags cannot be registered using the process in 2. Script subtags MUST immediately follow the primary language
Section 3.3 of this document. Variant subtags may be considered subtag and all extended language subtags and MUST occur before
any other type of subtag described below.
3. The script subtags 'Qaaa' through 'Qabx' are reserved for private
use in language tags. These subtags correspond to codes reserved
by ISO 15924 for private use. These codes MAY be used for non-
registered script values. Please refer to Section 4.4 for more
information on private-use subtags.
4. Script subtags cannot be registered using the process in
Section 3.4 of this document. Variant subtags may be considered
for registration for that purpose. for registration for that purpose.
Example: "de-Latn" represents German written using the Latin script. Example: "de-Latn" represents German written using the Latin script.
2.2.4 Region Subtag 2.2.4 Region Subtag
The following rules apply to the region subtags: The following rules apply to the region subtags:
o The region subtag defines language variations used in a specific 1. The region subtag defines language variations used in a specific
region, geographic, or political area. Region subtags MUST follow region, geographic, or political area. Region subtags MUST
any language, extended language, or script subtags and MUST follow any language, extended language, or script subtags and
precede all other subtags. MUST precede all other subtags.
o All 2-character subtags following the primary subtag were defined
in the IANA registry according to the assignments found in ISO
3166 [4]--"Codes for the representation of names of countries and
their subdivisions - Part 1: Country codes"--alpha-2 country codes
or assignments subsequently made by the ISO 3166 maintenance
agency or governing standardization bodies.
o All 3-character codes consisting of digit (numeric) characters
were defined in the IANA registry according to the assignments
found in UN Standard Country or Area Codes for Statistical Use
[5] or assignments subsequently made by the governing standards
body. Note that not all of the UN M.49 codes are defined in the
IANA registry:
* UN numeric codes assigned to 'macro-geographical (continental)'
or sub-regions not associated with an assigned ISO 3166 alpha-2
code _are_ defined.
* UN numeric codes for 'economic groupings' or 'other groupings'
are _not_ defined in the IANA registry and MUST NOT be used to
form language tags.
* Countries with ambiguous ISO 3166 alpha-2 codes as defined in
Section 3.2 are defined in the registry and are canonical for
the given country or region defined.
* The alphanumeric codes in Appendix X of the UN document are
_not_ defined and MUST NOT be used to form language tags. (At
the time this document was created these values match the ISO
3166 alpha-2 codes.)
o There may be at most one region subtag in a language tag.
o The subtags 'AA', 'QM'-'QZ', 'XA'-'XZ', and 'ZZ' are reserved for
private use in language tags. These subtags correspond to codes
reserved by ISO 3166 for private use. These codes MAY be used for
private use region subtags (instead of using a private-use subtag
sequence). Please refer to Section 2.5 for more information on
private use subtags.
"de-Latn-CH" represents German ('de') written using the Latin script 2. All two character subtags following the primary subtag were
('Latn') as used in Switzerland ('CH'). defined in the IANA registry according to the assignments found
in ISO 3166 [4]--"Codes for the representation of names of
countries and their subdivisions - Part 1: Country
codes"--alpha-2 country codes or assignments subsequently made by
the ISO 3166 maintenance agency or governing standardization
bodies.
3. All three character codes consisting of digit (numeric)
characters were defined in the IANA registry according to the
assignments found in UN Standard Country or Area Codes for
Statistical Use [5] or assignments subsequently made by the
governing standards body. Note that not all of the UN M.49 codes
are defined in the IANA registry:
A. UN numeric codes assigned to 'macro-geographical
(continental)' or sub-regions not associated with an assigned
ISO 3166 alpha-2 code _are_ defined.
B. UN numeric codes for 'economic groupings' or 'other
groupings' are _not_ defined in the IANA registry and MUST
NOT be used to form language tags.
C. UN numeric codes for countries with ambiguous ISO 3166
alpha-2 codes as defined in Section 3.3 are defined in the
registry and are canonical for the given country or region
defined.
D. The alphanumeric codes in Appendix X of the UN document are
_not_ defined and MUST NOT be used to form language tags.
(At the time this document was created these values match the
ISO 3166 alpha-2 codes.)
4. There may be at most one region subtag in a language tag.
5. The region subtags 'AA', 'QM'-'QZ', 'XA'-'XZ', and 'ZZ' are
reserved for private use in language tags. These subtags
correspond to codes reserved by ISO 3166 for private use. These
codes MAY be used for private use region subtags (instead of
using a private-use subtag sequence). Please refer to
Section 4.4 for more information on private use subtags.
"de-CH" represents German ('de') as used in Switzerland ('CH').
"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') as used in the UN-defined Latin "es-419" represents Spanish ('es') as used in the UN-defined Latin
America and Caribbean region ('419'). America and Caribbean region ('419').
2.2.5 Variant Subtags 2.2.5 Variant Subtags
The following rules apply to the variant subtags: The following rules apply to the variant subtags:
o Variant subtags, as a collection in the IANA registry, are not 1. Variant subtags are not associated with any external standard.
associated with any external standard. Variant subtags and their Variant subtags and their meanings are defined by the
meanings are defined by the registration process defined in registration process defined in Section 3.4.
Section 3.3.
o 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.
o More than one variant MAY be used to form the language tag.
o Variant subtags MUST be registered with IANA according to the 3. More than one variant MAY be used to form the language tag.
rules in Section 3.3 of this document before being used to form
4. Variant subtags MUST be registered with IANA according to the
rules in Section 3.4 of this document before being used to form
language tags. In order to distinguish variants from other types language tags. In order to distinguish variants from other types
of subtags, registrations must meet the following length and of subtags, registrations must meet the following length and
content restrictions: content restrictions:
* Variant subtags that begin with a letter (a-z, A-Z) MUST be at
least five characters long.
* Variant subtags that begin with a digit (0-9) MUST be at least
four characters long.
* The maximum length of a variant subtag is eight characters
long.
"en-boont" represents the Boontling dialect of English. 1. Variant subtags that begin with a letter (a-z, A-Z) MUST be
at least five characters long.
2. Variant subtags that begin with a digit (0-9) MUST be at
least four characters long.
"en-scouse" represents the Scouse dialect of English.
"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.
2.2.6 Extension Subtags 2.2.6 Extension Subtags
The following rules apply to extensions: The following rules apply to extensions:
o Extension subtags are separated from the other subtags defined in 1. Extension subtags are separated from the other subtags defined
this document by a single-letter subtag ("singleton"). The in this document by a single-letter subtag ("singleton"). The
singleton MUST be one allocated to a registration authority via singleton MUST be one allocated to a registration authority via
the mechanism described in Section 3.4 and cannot be the letter the mechanism described in Section 3.6 and cannot be the letter
'x', which is reserved for private-use subtag sequences. 'x', which is reserved for private-use subtag sequences.
o Note: Private-use subtag sequences starting with the singleton
2. Note: Private-use subtag sequences starting with the singleton
subtag 'x' are described below. subtag 'x' are described below.
o An extension MUST follow at least a primary language subtag. That 3. An extension MUST follow at least a primary language subtag.
is, a language tag cannot begin with an extension. Extensions That is, a language tag cannot begin with an extension.
extend language tags, they do not override or replace them. For Extensions extend language tags, they do not override or replace
example, "a-value" is not a well-formed language tag, while them. For example, "a-value" is not a well-formed language tag,
"de-a-value" is. while "de-a-value" is.
o Each singleton subtag MUST appear at most one time in each tag
(other than as a private-use subtag). That is, singleton subtags 4. Each singleton subtag MUST appear at most one time in each tag
MUST NOT be repeated. For example, the tag "en-a-bbb-a-ccc" is (other than as a private-use subtag). That is, singleton
invalid because the subtag 'a' appears twice. subtags MUST NOT be repeated. For example, the tag "en-a-bbb-a-
o Extension subtags MUST meet all of the requirements for the ccc" is invalid because the subtag 'a' appears twice. Note that
the tag "en-a-bbb-x-a-ccc" is valid because the second
appearance of the singleton 'a' is in a private use sequence.
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.
o 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.
o 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 '-'.
o Each singleton MUST be followed by at least one extension subtag.
For example, the tag "tlh-a-b-foo" is invalid because the first 8. Each singleton MUST be followed by at least one extension
singleton 'a' is followed immediately by another singleton 'b'. subtag. For example, the tag "tlh-a-b-foo" is invalid because
o Extension subtags MUST follow all language, extended language, the first singleton 'a' is followed immediately by another
singleton 'b'.
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.
o 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' defined subtag 'Latn' does not represent the script subtag 'Latn'
in the IANA Language Subtag Registry. Its meaning is defined by defined in the IANA Language Subtag Registry. Its meaning is
the extension 'a'. defined by the extension 'a'.
o In the event that more than one extension appears in a single tag,
the tag SHOULD be canonicalized as described in Section 2.4.1. 11. In the event that more than one extension appears in a single
tag, the tag SHOULD be canonicalized as described in
Section 4.3.
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: defined, then the following tag would be a valid example: "en-Latn-
"en-Latn-GB-boont-r-extended-sequence-x-private" GB-boont-r-extended-sequence-x-private"
2.2.7 Private Use Subtags 2.2.7 Private Use Subtags
The following rules apply to private-use subtags: The following rules apply to private-use subtags:
o 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'.
o Private-use subtags MUST follow all language, extended language,
2. Private-use subtags MUST follow all language, extended language,
script, region, variant, and extension subtags in the tag. script, region, variant, and extension subtags in the tag.
Another way of saying this is that all subtags following the Another way of saying this is that all subtags following the
singleton 'x' MUST be considered private use. Example: The subtag singleton 'x' MUST be considered private use. Example: The
'US' in the tag "en-x-US" is a private use subtag. subtag 'US' in the tag "en-x-US" is a private use subtag.
o Unlike Extensions, a tag MAY consist entirely of private-use
subtags.
o No source is defined for private use subtags. Use of private use 3. A tag MAY consist entirely of private-use subtags.
subtags is by private agreement and SHOULD NOT be considered part
of this document. 4. No source is defined for private use subtags. Use of private use
subtags is by private agreement only.
For example: Users who wished to utilize SIL Ethnologue for For example: Users who wished to utilize SIL Ethnologue for
identification might agree to exchange tags such as identification might agree to exchange tags such as "az-Arab-x-AZE-
"az-Arab-x-AZE-derbend". This example contains two private-use derbend". This example contains two private-use subtags. The first
subtags. The first is 'AZE' and the second is 'derbend'. is 'AZE' and the second is 'derbend'.
2.2.8 Pre-Existing RFC 3066 Registrations 2.2.8 Pre-Existing 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
that are not defined by additions to this document maintain their maintain their validity. IANA will maintain these tags in the
validity. IANA will maintain these tags in the registry under either registry under either the "grandfathered" or "redundant" type. For
the "grandfathered" or "redundant" type. For more information see more information see Section 3.7.
Appendix C.
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
were valid for potential registration under RFC 3066. could have been registered under RFC 3066.
2.2.9 Possibilities for Registration
Possibilities for registration of subtags include:
o Primary language subtags for languages not listed in ISO 639 that
are not variants of any listed or registered language, can be
registered. At the time this document was created there were no
examples of this form of subtag. Before attempting to register a
language subtag, there MUST be an attempt to register the language
with ISO 639. No language subtags will be registered for codes
that exist in ISO 639-1 or ISO 639-2, which are under
consideration by the ISO 639 maintenance or registration
authorities, or which have never been attempted for registration
with those authorities. If ISO 639 has previously rejected a
language for registration, it is reasonable to assume that there
MUST be additional very compelling evidence of need before it will
be registered in the IANA registry (to the extent that it is very
unlikely that any subtags will be registered of this type).
o Dialect or other divisions or variations within a language, its
orthography, writing system, regional variation, or historical
usage may be registered as variant subtags. An example is the
'scouse' subtag (the Scouse dialect of English).
This document leaves the decision on what subtags are appropriate or
not to the registration process described in Section 3.3.
ISO 639 defines a maintenance agency for additions to and changes in
the list of languages in ISO 639. This agency is:
International Information Centre for Terminology (Infoterm)
Aichholzgasse 6/12, AT-1120
Wien, Austria
Phone: +43 1 26 75 35 Ext. 312 Fax: +43 1 216 32 72
ISO 639-2 defines a maintenance agency for additions to and changes
in the list of languages in ISO 639-2. This agency is:
Library of Congress
Network Development and MARC Standards Office
Washington, D.C. 20540 USA
Phone: +1 202 707 6237 Fax: +1 202 707 0115
URL: http://www.loc.gov/standards/iso639
The maintenance agency for ISO 3166 (country codes) is:
ISO 3166 Maintenance Agency
c/o International Organization for Standardization
Case postale 56
CH-1211 Geneva 20 Switzerland
Phone: +41 22 749 72 33 Fax: +41 22 749 73 49
URL: http://www.iso.org/iso/en/prods-services/iso3166ma/index.html
The registration authority for ISO 15924 (script codes) is:
Unicode Consortium Box 391476
Mountain View, CA 94039-1476, USA
URL: http://www.unicode.org/iso15924
The Statistics Division of the United Nations Secretariat maintains
the Standard Country or Area Codes for Statistical Use and can be
reached at:
Statistical Services Branch
Statistics Division
United Nations, Room DC2-1620
New York, NY 10017, USA
Fax: +1-212-963-0623
E-mail: statistics@un.org
URL: http://unstats.un.org/unsd/methods/m49/m49alpha.htm
2.2.10 Classes of Conformance 2.2.9 Classes of Conformance
Implementations may wish to express their level of conformance with Implementations may wish to express their level of conformance with
the rules and practices described in this document. There are the rules and practices described in this document. There are
generally two classes of conforming implementations: "well-formed" generally two classes of conforming implementations: "well-formed"
processors and "validating" processors. Claims of conformance SHOULD processors and "validating" processors. Claims of conformance SHOULD
explicitly reference one of these definitions. explicitly reference one of these definitions.
An implementation that claims to check for well-formed language tags An implementation that claims to check for well-formed language tags
MUST: MUST:
o Check that the tag and all of its subtags, including extension and o Check that the tag and all of its subtags, including extension and
private-use subtags, conform to the ABNF or that the tag is on the private-use subtags, conform to the ABNF or that the tag is on the
list of grandfathered tags. list of grandfathered tags.
o Check that singleton subtags that identify extensions do not o Check that singleton subtags that identify extensions do not
repeat. For example, the tag "en-a-xx-b-yy-a-zz" is not repeat. For example, the tag "en-a-xx-b-yy-a-zz" is not well-
well-formed. formed.
Well-formed processors are strongly encouraged to implement the Well-formed processors are strongly encouraged to implement the
canonicalization rules contained in Section 2.4.1. canonicalization rules contained in Section 4.3.
An implementation that claims to be validating MUST: An implementation that claims to be validating MUST:
o Check that the tag is well-formed. o Check that the tag is well-formed.
o Specify the particular registry date for which the implementation o Specify the particular registry date for which the implementation
performs validation of subtags. performs validation of subtags.
o Check that either the tag is a grandfathered tag, or that all o Check that either the tag is a grandfathered tag, or that all
language, script, region, and variant subtags consist of valid language, script, region, and variant subtags consist of valid
codes for use in language tags according to the IANA registry as codes for use in language tags according to the IANA registry as
of the particular date specified by the implementation. of the particular date specified by the implementation.
o Specify which, if any, extension RFCs as defined in Section 3.4
o Specify which, if any, extension RFCs as defined in Section 3.6
are supported, including version, revision, and date. are supported, including version, revision, and date.
o For any such extensions supported, check that all subtags used in o For any such extensions supported, check that all subtags used in
that extension are valid. that extension are valid.
o If the processor generates tags, it MUST do so in canonical form,
including any supported extensions, as defined in Section 2.4.1.
2.3 Choice of Language Tag
One may occasionally be faced with several possible tags for the same
body of text.
Interoperability is best served when all users use the same language
tag in order to represent the same language. If an application has
requirements that make the rules here inapplicable, then that
application risks damaging interoperability. It is STRONGLY
RECOMMENDED that users not define their own rules for language tag
choice.
Standards, protocols and applications that reference this document
normatively but apply different rules to the ones given in this
section MUST specify how the procedure varies from the one given
here.
1. Use as precise a tag as possible, but no more specific than is
justified. For example, 'de' might suffice for tagging an email
written in German, while "de-CH-1996" is probably unnecessarily
precise for such a task.
2. Avoid using subtags that are not important for distinguishing
content in an application. For example, including the script
subtag in "en-Latn-US" is generally unnecessary, since nearly all
English texts are written in the Latin script and it is generally
not important to filter out those few that are not.
3. Use the canonical subtag from the IANA registry in preference to
any of its aliases. For example, you should use 'he' for Hebrew
in preference to 'iw'.
4. You SHOULD NOT use the 'UND' (Undetermined) language subtag to
label content, even if the language is unknown. Omitting the tag
is preferred. Some protocols may force you to give a value for
the language tag and the 'UND' subtag may be useful when matching
language tags in certain situations.
5. You SHOULD NOT use the 'MUL' (Multiple) subtag if the protocol
allows you to use multiple languages, as is the case for the
Content-Language header in HTTP.
6. You SHOULD NOT use the same variant subtag more than once within
a language tag. For example, you should not use
"en-US-boont-boont".
To ensure consistent backward compatibility, this document contains
several provisions to account for potential instability in the
standards used to define the subtags that make up language tags.
These provisions mean that no language tag created under the rules in
this document will become obsolete. In addition, tags that are in
canonical form will always be in canonical form.
2.4 Meaning of the Language Tag
The language tag always defines a language as spoken (or written,
signed or otherwise signaled) by human beings for communication of
information to other human beings. Computer languages such as
programming languages are explicitly excluded.
If a language tag B contains language tag A as a prefix, then B is
typically "narrower" or "more specific" than A. For example,
"zh-Hant-TW" is more specific than "zh-Hant".
This relationship is not guaranteed in all cases: specifically,
languages that begin with the same sequence of subtags are NOT
guaranteed to be mutually intelligible, although they may be. For
example, the tag "az" shares a prefix with both "az-Latn"
(Azerbaijani written using the Latin script) and "az-Cyrl"
(Azerbaijani written using the Cyrillic script). A person fluent in
one script may not be able to read the other, even though the text
might be identical. Content tagged as "az" most probably is written
in just one script and thus might not be intelligible to a reader
familiar with the other script.
The relationship between the tag and the information it relates to is o If the processor generates tags, it MUST do so in canonical form,
defined by the standard describing the context in which it appears. including any supported extensions, as defined in Section 4.3.
Accordingly, this section can only give possible examples of its
usage.
o For a single information object, the associated language tags
might be interpreted as the set of languages that is required for
a complete comprehension of the complete object. Example: Plain
text documents.
o For an aggregation of information objects, the associated language
tags could be taken as the set of languages used inside components
of that aggregation. Examples: Document stores and libraries.
o For information objects whose purpose is to provide alternatives,
the associated language tags could be regarded as a hint that the
content is provided in several languages, and that one has to
inspect each of the alternatives in order to find its language or
languages. In this case, the presence of multiple tags might not
mean that one needs to be multi-lingual to get complete
understanding of the document. Example: MIME
multipart/alternative.
o In markup languages, such as HTML and XML, language information
can be added to each part of the document identified by the markup
structure (including the whole document itself). For example, one
could write <span lang="FR">C'est la vie.</span> inside a
Norwegian document; the Norwegian-speaking user could then access
a French-Norwegian dictionary to find out what the marked section
meant. If the user were listening to that document through a
speech synthesis interface, this formation could be used to signal
the synthesizer to appropriately apply French text-to-speech
pronunciation rules to that span of text, instead of misapplying
the Norwegian rules.
2.4.1 Canonicalization of Language Tags 3. Registry Format and Maintenance
Since a particular language tag may be used in many processes, This section defines the Language Subtag Registry and the maintenance
language tags SHOULD always be created or generated in a canonical and update procedures associated with it.
form.
A language tag is in canonical form when: The language subtag registry will be maintained so that, except for
1. The tag is well-formed according the rules in Section 2.1 and extension subtags, it is possible to validate all of the subtags that
Section 2.2. appear in a language tag under the provisions of this document or its
2. None of the subtags in the language tag has a canonical_value revisions or successors. In addition, the meaning of the various
mapping in the IANA registry (see Section 3.1). Subtags with a subtags will be unambiguous and stable over time. (The meaning of
canonical_value mapping MUST be replaced with their mapping in private-use subtags, of course, is not defined by the IANA registry.)
order to canonicalize the tag.
3. If more than one extension subtag sequence exists, the extension
sequences are ordered into case-insensitive ASCII order by
singleton subtag.
Example: The language tag "en-A-aaa-B-ccc-bbb-x-xyz" is in canonical The registry defined under this document contains a comprehensive
form, while "en-B-ccc-bbb-A-aaa-X-xyz" is well-formed but not in list of all of the subtags valid in language tags. This allows
canonical form. implementers a straightforward and reliable way to validate language
tags.
Example: The language tag "en-NH" (English as used in the New 3.1 Format of the IANA Language Subtag Registry
Hebrides) is not canonical because the 'NH' subtag has a canonical
mapping to 'VU' (Vanuatu).
Note: Canonicalization of language tags does not imply anything about The IANA Language Subtag Registry ("the registry") will consist of a
the use of upper or lowercase letter in subtags as described in text file that is machine readable in the format described in this
Section 2.1. All comparisons MUST be performed in a case-insensitive section, plus copies of the registration forms approved by the
manner. Language Subtag Reviewer in accordance with the process described in
Section 3.4. With the exception of the registration forms for
grandfathered and redundant tags, no registration records will be
maintained for the initial set of subtags.
Note: the value "--" in the canonical_value field of the registry The registry will be in a modified record-jar format text file [17].
indicates a tag or subtag that has been deprecated and for which no Lines are limited to 72 characters, including all whitespace.
replacement or canonical equivalent has been assigned. Validating
processors SHOULD NOT generate tags that include these values.
An extension MUST define any relationships that may exist between the Records are separated by lines containing only the sequence "%%"
various subtags in the extension and thus MAY define an alternate (%x25.25).
canonicalization scheme for the extension's subtags. Extensions MAY
define how the order of the extension's subtags are interpreted. For
example, an extension could define that its subtags are in canonical
order when the subtags are placed into ASCII order: that is,
"en-a-aaa-bbb-ccc" instead of "en-a-ccc-bbb-aaa". Another extension
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-aaa-bbb-ccc"). However, extension specifications SHOULD be
designed so that they are tolerant of the typical processes described
in Section 3.4.
2.5 Considerations for Private Use Subtags Each field can be viewed as a single, logical line of ASCII
characters, comprising a field-name and a field-body separated by a
COLON character (%x3A). For convenience, the field-body portion of
this conceptual entity can be split into a multiple-line
representation; this is called "folding". The format of the registry
is described by the following ABNF (per [7]):
Private-use subtags require private agreement between the parties registry = record *("%%" CRLF record)
that intend to use or exchange language tags that use them and great record = 1*( field-name *SP ":" *SP field-body CRLF )
caution should be used in employing them in content or protocols field-name = *(ALPHA/NUM/"-")
intended for general use. Private-use subtags are simply useless for field-body = *(ASCCHAR/LWSP)
information exchange without prior arrangement. ASCCHAR = %x21-25 / %x27-7E / UNICHAR ; Note: AMPERSAND is %x26
UNICHAR = "&#x" 2*6HEXDIG ";"
The value and semantic meaning of private-use tags and of the subtags The sequence '..' (%x2E.2E) in a field-body denotes a range of
used within such a language tag are not defined by this document. values. Such a range represents all subtags of the same length that
are alphabetically within that range, including the values explicitly
mentioned. For example 'a..c' denotes the values 'a', 'b', and 'c'.
The use of subtags defined in the IANA registry as having a specific Characters from outside the US-ASCII repertoire, as well as the
private use meaning convey more information that a purely private use AMPERSAND character ("&", %x26) when it occurs in a field-body are
tag prefixed by the singleton subtag 'x'. For applications this represented by a "Numeric Character Reference" using hexadecimal
additional information may be useful. notation in the style used by XML 1.0 [18] (see
<http://www.w3.org/TR/REC-xml/#dt-charref>). This consists of the
sequence "&#x" (%x26.23.78) followed by a hexadecimal representation
of the character's code point in ISO/IEC 10646 [6] followed by a
closing semicolon (%x3B). For example, the EURO SIGN, U+20AC, would
be represented by the sequence "&#x20AC;". Note that the hexadecimal
notation may have between two and six digits.
For example, the region subtags 'AA', 'ZZ' and in the ranges All fields whose field-body contains a date value use the "full-date"
'QM'-'QZ' and 'XA'-'XZ' (derived from ISO 3166 private use codes) may format specified in RFC 3339 [14]. For example: "2004-06-28"
be used to form a language tag. A tag such as "zh-Hans-XQ" conveys a represents June 28, 2004 in the Gregorian calendar.
great deal of public, interchangeable information about the language
material (that it is Chinese in the simplified Chinese script and is
suitable for some geographic region 'XQ'). While the precise
geographic region is not known outside of private agreement, the tag
conveys far more information than an opaque tag such as "x-someLang",
which contains no information about the language subtag or script
subtag outside of the private agreement.
However, in some cases content tagged with private use subtags may The first record in the file contains the single field whose field-
interact with other systems in a different and possibly unsuitable name is "File-Date" and whose field-body contains the last
manner compared to tags that use opaque, privately defined subtags, modification date of the registry:
so the choice of the best approach may depend on the particular
domain in question.
3. IANA Considerations File-Date: 2004-06-28
%%
This section deals with the processes and requirements necessary to Subsequent records represent subtags in the registry. Each of the
maintain the registry of subtags and extensions for use in language fields in each record MUST occur no more than once, unless otherwise
tags as defined by this document and in accordance with the noted below. Each record MUST contain the following fields:
requirements of RFC 2434 [15].
The language subtag registry will be maintained so that, except for o 'Type'
extension subtags, it is possible to validate all of the subtags that
appear in a language tag under the provisions of this document or its
revisions or successors. In addition, the meaning of the various
subtags will be unambiguous and stable over time. (The meaning of
private-use subtags, of course, is not defined by the IANA registry.)
The registry defined under this document contains a comprehensive * Type's field-value MUST consist of one of the following
list of all of the subtags valid in language tags. This allows strings: "language", "extlang", "script", "region", "variant",
implementers a straightforward and reliable way to validate language "grandfathered", and "redundant" and denotes the type of tag or
tags. subtag.
3.1 Format of the IANA Language Subtag Registry o Either 'Subtag' or 'Tag'
The IANA Language Subtag Registry will consist of a text file that is * Subtag's field-value contains the subtag being defined. This
machine readable in the format described in this section, plus copies field MUST only appear in records of whose Type has one of
of the registration forms approved by the Language Subtag Reviewer in these values: "language", "extlang", "script", "region", or
accordance with the process described in Section 3.3. With the "variant".
exception of the registration forms for grandfathered and redundant
tags, no registration records will be maintained for the initial set
of subtags.
Each record in the subtag registry will consist of a series of fields * Tag's field-value contains a complete language tag. This field
separated by the symbol "|" (%x7D) and terminated by a newline. Text MUST only appear in records whose Type has one of these values:
appearing after the symbol "#" (%x23) contains comments. Whitespace "grandfathered" or "redundant".
surrounding fields in the file is ignored. If a field contains more
than one value, the values are separated by semicolons (%x3B).
There is a single date record at the start of the file which o Description
indicates the most recent modification date of the file. It has two
fields: the type field is "date", and the second field is the
modification date, in the "full-date" format specified in RFC 3339
[20]. For example: 2004-06-28 represents June 28, 2004 in the
Gregorian calendar:
date | 2004-06-28
The fields in each subtag record, in order, are: * Description's field-value contains a non-normative description
type| subtag| description| date| canonical_value| of the subtag or tag.
recommended_prefix # comments
o The character "vertical line" ("|", %x7D) delimits each of the
fields.
o Empty fields (and their separators) at the end of the record may
be omitted.
o Leading or trailing whitespace in each field is not part of the
content.
o When the type is "grandfathered" or "redundant", then the subtag
field is actually a whole tag.
o The "recommended_prefix" field is empty, except where the type is
"variant"
o The "comments" field is optional and appears only at the end of a
record, following a "number sign" ("#", %x23).
o The sequence '..' denotes a range of values. Such a range
represents all subtags of the same length that are alphabetically
within that range, including the values explicitly mentioned. For
example 'a..c' denotes the values 'a', 'b', and 'c'.
The field 'type' MUST consist of one of the following strings: o Added
"language", "extlang", "script", "region", "variant",
"grandfathered", and "redundant" and denotes the type of subtag (or
tag, in the case of "grandfathered" and "redundant").
The field 'subtag' contains the subtag being defined. * Added's field-value contains the date the record was added to
the registry.
The field 'description' contains a description of the subtag The field 'Description' MAY appear more than one time. The
transcribed into ASCII. 'Description' field must contain a description of the tag being
registered written or transcribed into the Latin script; it may also
include a description in a non-Latin script. The 'Description' field
is used for identification purposes and should not be taken to
represent the actual native name of the language or variation or to
be in any particular language. Most descriptions are taken directly
from 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.
and localization or translation of language tag and subtag Localization or translation of language tag and subtag descriptions
descriptions is out of scope of this document. is out of scope of this document.
The field 'date' contains the date the record was added to the Each record MAY also contain the following fields:
registry in the "full-date" format specified in RFC 3339 [20]. For
example: 2004-06-28 represents June 28, 2004, in the Gregorian
calendar.
The field 'canonical value' represents a canonical mapping of this o Canonical
record to a subtag record of the same 'type', except for records of
type "grandfathered" and "redundant". This field SHALL NOT be
modified (except for records of type "grandfathered"): therefore a
subtag whose record contains no canonical mapping when the record is
created is a canonical form and will remain so. The 'canonical
value' field in records of type "grandfathered" and "redundant"
contain whole language tags that are STRONGLY RECOMMENDED for use in
place of the record's value. In many cases the mappings were created
by deprecation of the tags during the period before this document was
adopted. For example, the tag "no-nyn" was deprecated in favor of
the ISO 639-1 defined language code 'nn'.
The value "--" in the 'canonical value' field means that the tag or * For fields of type 'language', 'extlang', 'script', 'region',
subtag has been deprecated and that no replacement value has been and 'variant', a canonical mapping of this record to a subtag
assigned. For example, the "region" code 'BQ' (British Antarctic record of the same 'Type'.
Territory) was withdrawn by ISO 3166 in 1979. Although valid in
language tags, it is deprecated and validating processors SHOULD NOT
generate this subtag.
The field 'recommended prefix' is for use with registered variants * For fields of type 'grandfathered' and 'redundant', a canonical
and contains a semicolon separated list of language-ranges considered mapping to a complete language tag.
most appropriate for use with this subtag. Additional values can be
added to this field for variants only via additional registration.
Other modification of this field (such as removing or changing
values) is not permitted.
The field 'comments' may contain additional information about the o Deprecated
subtag, as deemed appropriate for understanding the registry and
implementing language tags using the various subtags. These values
can be changed via the registration process and no guarantee of
stability is provided.
# IANA Language Subtag Registry * Deprecated's field-value contains the date the record was
# This registry lists all valid subtags for language tags deprecated.
# created under RFC XXXX.
date| 2004-08-07
# language codes: ISO 639 and registered codes o Recommended-Prefix
# ISO 639-1 (alpha-2) codes * Recommended-Prefix's field-value contains a language tag with
language| aa| Afar| 2004-07-06| | which this subtag may be used to form a new language tag,
language| ab| Abkhazian| 2004-07-06| | perhaps with other subtags as well. This field MUST only
language| ae| Avestan| 2004-07-06| | appear in records whose 'Type' field-value is 'variant' or
language| he| hebrew| 2004-06-28| | 'extlang'. For example, the 'Recommended-Prefix' for the
language| iw| hebrew| 2004-06-28| he | #note mapping variant 'scouse' is 'en', meaning that the tags "en-scouse" and
language| qaa..qtz| PRIVATE USE| 2004-07-06| | "en-GB-scouse" might be appropriate while the tag "is-scouse"
language| raj| Rajasthani| 2004-07-06| | is not.
language| seuss| Hypothetical Language| 2005-04-01 | |# registered language
# script codes: ISO 15924 o Comments
script| Arab| Arabic| 2004-07-06| | * Comments contains additional information about the subtag, as
script| Armn| Armenian| 2004-07-06| | deemed appropriate for understanding the registry and
script| Bali| Balinese| 2004-07-06| | implementing language tags using the subtag or tag.
# region codes: ISO 3166 and UN codes
# ISO 3166-1 alpha-2 codes o Suppress-Script
region| AA| PRIVATE USE| 2004-08-01| | * Suppress-Script contains a script subtag that SHOULD NOT be
region| AD| Andorra| 2004-07-06| | used to form language tags with the associated primary language
region| AE| United Arab Emirates| 2004-07-06| | subtag. This field MUST only appear in records whose 'Type'
region| AF| Afghanistan| 2004-07-06| | field-value is 'language'. See Section 4.1.
region| BQ| British Antarctic Territory | 2004-07-06 | -- | # deprecated 1979
region| CS| Serbia and Montenegro| 2003-07-23| |
region| YU| Yugoslavia| 2004-06-28| |
# United Nations M.49 numeric codes The field 'Canonical' SHALL NOT be added to any record already in the
region| 001| World| 2004-07-06| | registry. The field 'Canonical' SHALL NOT be modified except for
region| 002| Africa| 2004-07-06| | records of type "grandfathered": therefore a subtag whose record
region| 003| North America| 2004-07-06| | contains no canonical mapping when the record is created is a
region| 005| South America| 2004-07-06| | canonical form and will remain so.
region| 200| Czechoslovakia| 2004-07-06| | #formerly used code CS
## registered variants The 'Canonical' field in records of type "grandfathered" and
"redundant" contains whole language tags that are STRONGLY
RECOMMENDED for use in place of the record's value. In many cases
the mappings were created by deprecation of the tags during the
period before this document was adopted. For example, the tag "no-
nyn" was deprecated in favor of the ISO 639-1 defined language code
'nn'.
variant| boont| Boontling| 2003-02-14| | en Note that a record that has a 'Canonical' field MUST have a
variant| gaulish| Gaulish| 2001-05-25| | cel 'Deprecated' field also (although the converse is not true).
variant| guoyu| Mandarin or Standard Chinese| 1999-12-18| | zh
# grandfathered from RFC 3066 The field 'Deprecated' MAY be added to any record via the maintenance
process described in Section 3.2 or via the registration process
described in Section 3.4. Usually the addition of a 'Deprecated'
field is due to the action of one of the standards bodies, such as
ISO 3166, withdrawing a code. In some historical cases it may not
have been possible to reconstruct the original deprecation date.
For these cases, an approximate date appears in the registry.
Although valid in language tags, subtags and tags with a 'Deprecated'
field are deprecated and validating processors SHOULD NOT generate
these subtags. Note that a record that contains a 'Deprecated' field
and no corresponding 'Canonical' field has no replacement mapping.
grandfathered| en-GB-oed| English, Oxford English Dictionary spelling| 2003-07-09| | The field 'Recommended-Prefix' MAY appear more than once per record.
grandfathered| i-ami| Amis| 1999-05-25| | Additional fields of this type MAY be added to a record via the
grandfathered| i-bnn| Bunun| 1999-05-25| | registration process. The field-value of of this field consists of a
grandfathered| art-lojban| Lojban| 2001-11-11|jbo | # deprecated in favor of 'jbo' language tag that is RECOMMENDED for use as a prefix for this subtag.
For example, the variant subtag 'scouse' has a recommended prefix of
"en". This means that tags starting with the prefix "en-" are most
appropriate with this subtag, so "en-Latn-scouse" and "en-GB-scouse"
are both acceptable, while the tag "fr-scouse" is probably an
inappropriate choice.
# redundant The field of type Recommended-Prefix MUST NOT be removed from any
# The following codes were registered as complete tags, but can now be record. The field-value for this type of field MUST NOT be modified.
# composed of registered subtags and do not require registration.
redundant| az-Arab| Azerbaijani in Arabic script| 2003-05-30| | # use language az + script Arab The field 'Comments' MAY appear more than once per record. This
redundant| az-Cyrl| Azerbaijani in Cyrillic script| 2003-05-30| | # use language az + script Cyrl field MAY be inserted or changed via the registration process and no
redundant| en-boont| Boontling| 2003-02-14| | # use language en + variant boont guarantee of stability is provided. The content of this field is not
restricted, except by the need to register the information, the
suitability of the request, and by reasonable practical size
limitations. Long screeds about a particular subtag are frowned
upon.
Figure 2: Example of the Registry Format The field 'Suppress-Script' MUST only appear in records whose 'Type'
field-value is 'language'. This field may appear at most one time in
a record. This field indicates a script used to write the
overwhelming majority of documents for the given language and which
therefore adds no distinguishing information to a language tag. For
example, virtually all Icelandic documents are written in the Latin
script, making the subtag 'Latn' redundant in the tag "is-Latn".
For examples of registry entries and their format, see Appendix C.
3.2 Maintenance of the Registry
Maintenance of the registry requires that as new codes are assigned Maintenance of the registry requires that as new codes are assigned
by ISO 639, ISO 15924, and ISO 3166, the Language Subtag Reviewer by ISO 639, ISO 15924, and ISO 3166, the Language Subtag Reviewer
will evaluate each assignment, determine whether it conflicts with will evaluate each assignment, determine whether it conflicts with
existing registry entries, and submit the information to IANA for existing registry entries, and submit the information to IANA for
inclusion in the registry. inclusion in the registry. If an assignment takes place and the
Language Subtag Reviewer does not do this in a timely manner, then
any interested party may use the procedure in Section 3.4 to register
the appropriate update.
Note: The redundant and grandfathered entries together are the Note: The redundant and grandfathered entries together are the
complete list of tags registered under RFC 3066 [18]. The redundant complete list of tags registered under RFC 3066 [23]. The redundant
tags are those that can now be formed using the subtags defined in tags are those that can now be formed using the subtags defined in
Section 2.2. The grandfathered entries are those that can never be the registry together with the rules of Section 2.2. The
legal under those same provisions. The items in both lists are grandfathered entries are those that can never be legal under those
permanent and stable, although grandfathered items may be deprecated same provisions. The items in both lists are permanent and stable,
over time. Refer to Appendix C for more information. although grandfathered items may be deprecated over time. Refer to
Section 3.7 for more information.
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 they remain eligible for registration). For example, the tag "art-
"art-lojban" was deprecated in favor of the language subtag 'jbo'. 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 2.3 or submit an appropriate alternate subtag requirements in Section 4.1 or submit an appropriate alternate subtag
as described in that section. She or he will use the following form as described in that section. If a change or addition to the
to submit this information: registry is required, the Language Subtag Reviewer will prepare the
complete record, including all fields, and forward it to IANA for
LANGUAGE SUBTAG REGISTRATION FORM (NEW RECORD) insertion into the registry. If this represents a new subtag, then
Record Text: the message will indicate that this represents an INSERTION of a
Type: record. If this represents a change to an existing subtag, then the
Subtag: message must indicate that this represents a MODIFICATION, as shown
Description: in the following example:
Date:
Canonical Mapping:
Recommended Prefix:
Comments:
Figure 3 LANGUAGE SUBTAG MODIFICATION
File-Date: 2005-01-02
%%
Type: variant
Subtag: nedis
Description: Natisone dialect
Description: Nadiza dialect
Added: 2003-10-09
Recommended-Prefix: sl
Comments: This is a comment shown
as an example.
%%
The field 'record text' contains the exact record that IANA is to Figure 4
insert into the Language Subtag Registry. The contents of the
remaining fields must exactly match those in this field.
Whenever an entry is created or modified in the registry, the 'date' Whenever an entry is created or modified in the registry, the 'File-
record at the start of the registry is updated to reflect the most Date' record at the start of the registry is updated to reflect the
recent modification date in the RFC 3339 [20] "full-date" format. most recent modification date in the RFC 3339 [14] "full-date"
format.
3.2 Stability of IANA Registry Entries 3.3 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 and that the choice of language stable over time and will not change and that the choice of language
tag for specific content is also stable over time. tag for specific content is also stable over time.
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:
o Values in the fields 'type', 'subtag', 'date' and 'canonical
value' MUST NOT be changed and are guaranteed to be stable over o Values in the fields 'Type', 'Subtag', 'Tag', 'Added' and
time. 'Canonical' MUST NOT be changed and are guaranteed to be stable
o Values in the 'description' field MUST NOT be changed in a way over time.
o 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 of occasionally change their official names: an historical example of
this would be "Upper Volta" changing to "Burkina Faso". this would be "Upper Volta" changing to "Burkina Faso".
o Values in the field 'recommended prefix' MAY be added via the
o Values in the field 'Recommended-Prefix' MAY be added via the
registration process. registration process.
o Values in the field 'recommended prefix' MAY be modified, so long
o Values in the field 'Recommended-Prefix' MAY be modified, so long
as the modifications broaden the set of recommended prefixes. as the modifications broaden the set of recommended prefixes.
That is, a recommended prefix MAY be replaced by one of its own That is, a recommended prefix MAY be replaced by one of its own
prefixes. For example, the prefix "en-US" could be replaced by prefixes. For example, the prefix "en-US" could be replaced by
"en", but not by the ranges "en-Latn", "fr", or "en-US-boont". "en", but not by the ranges "en-Latn", "fr", or "en-US-boont".
o Values in the field 'recommended prefix' MUST NOT be removed.
o The field 'comments' MAY be added, changed, modified, or removed o Values in the field 'Recommended-Prefix' MUST NOT be removed.
o The field 'Comments' MAY be added, changed, modified, or removed
via the registration process or any of the processes or via the registration process or any of the processes or
considerations described in this section. considerations described in this section.
o The field 'Suppress-Script' MAY be added or removed via the
registration process.
o Codes assigned by ISO 639, ISO 15924, and ISO 3166 that do not o Codes assigned by ISO 639, ISO 15924, and ISO 3166 that do not
conflict with existing subtags of the associated type and whose conflict with existing subtags of the associated type and whose
meaning is not the same as an existing subtag of the same type are meaning is not the same as an existing subtag of the same type are
entered into the IANA registry as new records and their value is entered into the IANA registry as new records and their value is
canonical for the meaning assigned to them. canonical for the meaning assigned to them.
o Codes assigned by ISO 639, ISO 15924, or ISO 3166 that are o 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. The registration process authority remain valid in language tags. The registration process
MAY be used to add a note indicating the withdrawal of the code by MAY be used to add a note indicating the withdrawal of the code by
the respective standard. the respective standard.
o Codes assigned by ISO 639, ISO 15924, or ISO 3166 that do not o Codes assigned by ISO 639, ISO 15924, or ISO 3166 that do not
conflict with existing subtags of the associated type but which conflict with existing subtags of the associated type but which
represent the same meaning as an existing subtag of that type are represent the same meaning as an existing subtag of that type are
entered into the IANA registry as new records. The field entered into the IANA registry as new records. The field
'canonical value' for that record MUST contain the existing subtag 'canonical value' for that record MUST contain the existing subtag
of the same meaning of the same meaning
Example If ISO 3166 were to assign the code 'IM' to represent the Example If ISO 3166 were to assign the code 'IM' to represent the
value "Isle of Man" (represented in the IANA registry by the UN value "Isle of Man" (represented in the IANA registry by the UN
M.49 code '833'), '833' remains the canonical subtag and 'IM' M.49 code '833'), '833' remains the canonical subtag and 'IM'
would be assigned '833' as a canonical value. This prevents would be assigned '833' as a canonical value. This prevents
tags that are in canonical form from becoming non-canonical. tags that are in canonical form from becoming non-canonical.
Example If the tag 'enochian' were registered as a primary Example If the tag 'enochian' were registered as a primary
language subtag and ISO 639 subsequently assigned an alpha-3 language subtag and ISO 639 subsequently assigned an alpha-3
code to the same language, the new ISO 639 code would be code to the same language, the new ISO 639 code would be
entered into the IANA registry as a subtag with a canonical entered into the IANA registry as a subtag with a canonical
skipping to change at page 26, line 11 skipping to change at page 24, line 24
M.49 code '833'), '833' remains the canonical subtag and 'IM' M.49 code '833'), '833' remains the canonical subtag and 'IM'
would be assigned '833' as a canonical value. This prevents would be assigned '833' as a canonical value. This prevents
tags that are in canonical form from becoming non-canonical. tags that are in canonical form from becoming non-canonical.
Example If the tag 'enochian' were registered as a primary Example If the tag 'enochian' were registered as a primary
language subtag and ISO 639 subsequently assigned an alpha-3 language subtag and ISO 639 subsequently assigned an alpha-3
code to the same language, the new ISO 639 code would be code to the same language, the new ISO 639 code would be
entered into the IANA registry as a subtag with a canonical entered into the IANA registry as a subtag with a canonical
mapping to 'enochian'. The new ISO code can be used, but it is mapping to 'enochian'. The new ISO code can be used, but it is
not canonical. not canonical.
o Codes assigned by ISO 639, ISO 15924, or ISO 3166 that conflict o Codes assigned by ISO 639, ISO 15924, or ISO 3166 that conflict
with existing subtags of the associated type MUST NOT be entered with existing subtags of the associated type MUST NOT be entered
into the registry. The following additional considerations apply: into the registry. The following additional considerations apply:
* For ISO 639 codes, if the newly assigned code's meaning is not * For ISO 639 codes, if the newly assigned code's meaning is not
represented by a subtag in the IANA registry, the Language represented by a subtag in the IANA registry, the Language
Subtag Reviewer, as described in Section 3.3, shall prepare a Subtag Reviewer, as described in Section 3.4, shall prepare a
proposal for entering in the IANA registry as soon as practical proposal for entering in the IANA registry as soon as practical
a registered language subtag as an alternate value for the new a registered language subtag as an alternate value for the new
code. The form of the registered language subtag will be at code. The form of the registered language subtag will be at
the discretion of the Language Subtag Reviewer and must conform the discretion of the Language Subtag Reviewer and must conform
to other restrictions on language subtags in this document. to other restrictions on language subtags in this document.
* For all subtags whose meaning is derived from an external * For all subtags whose meaning is derived from an external
standard (i.e. ISO 639, ISO 15924, ISO 3166, or UN M.49), if a 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 meaning new meaning is assigned to an existing code and the new meaning
broadens the meaning of that code, then the meaning for the broadens the meaning of that code, then the meaning for the
associated subtag MAY be changed to match. The meaning of a associated subtag MAY be changed to match. The meaning of a
subtag MUST NOT be narrowed, however, as this can result in an subtag MUST NOT be narrowed, however, as this can result in an
unknown proportion of the existing uses of a subtag becoming unknown proportion of the existing uses of a subtag becoming
invalid. Note: ISO 639 MA/RA has adopted a similar stability invalid. Note: ISO 639 MA/RA has adopted a similar stability
policy. policy.
* For ISO 15924 codes, if the newly assigned code's meaning is * For ISO 15924 codes, if the newly assigned code's meaning is
not represented by a subtag in the IANA registry, the Language not represented by a subtag in the IANA registry, the Language
Subtag Reviewer, as described in Section 3.3, shall prepare a Subtag Reviewer, as described in Section 3.4, shall prepare a
proposal for entering in the IANA registry as soon as practical proposal for entering in the IANA registry as soon as practical
a registered variant subtag as an alternate value for the new a registered variant subtag as an alternate value for the new
code. The form of the registered variant subtag will be at the code. The form of the registered variant subtag will be at the
discretion of the Language Subtag Reviewer and must conform to discretion of the Language Subtag Reviewer and must conform to
other restrictions on variant subtags in this document. other restrictions on variant subtags in this document.
* For ISO 3166 codes, if the newly assigned code's meaning is * For ISO 3166 codes, if the newly assigned code's meaning is
associated with the same UN M.49 code as another 'region' associated with the same UN M.49 code as another 'region'
subtag, then the existing region subtag remains as the subtag, then the existing region subtag remains as the
canonical entry for that region and no new entry is created. A canonical entry for that region and no new entry is created. A
note MAY be added to the existing region subtag indicating the comment MAY be added to the existing region subtag indicating
relationship to the new ISO 3166 code. the relationship to the new ISO 3166 code.
* For ISO 3166 codes, if the newly assigned code's meaning is * For ISO 3166 codes, if the newly assigned code's meaning is
associated with a UN M.49 code that is not represented by an associated with a UN M.49 code that is not represented by an
existing region subtag, then then the Language Subtag Reviewer, existing region subtag, then then the Language Subtag Reviewer,
as described in Section 3.3, shall prepare a proposal for as described in Section 3.4, shall prepare a proposal for
entering the appropriate numeric UN country code as an entry in entering the appropriate numeric UN country code as an entry in
the IANA registry. the IANA registry.
* For ISO 3166 codes, if there is no associated UN numeric code, * For ISO 3166 codes, if there is no associated UN numeric code,
then the Language Subtag Reviewer SHALL petition the UN to then the Language Subtag Reviewer SHALL petition the UN to
create one. If there is no response from the UN within ninety create one. If there is no response from the UN within ninety
days of the request being sent, the Language Subtag Reviewer days of the request being sent, the Language Subtag Reviewer
shall prepare a proposal for entering in the IANA registry as shall prepare a proposal for entering in the IANA registry as
soon as practical a registered variant subtag as an alternate soon 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. This situation is very unlikely to subtags in this document. This situation is very unlikely to
skipping to change at page 27, line 24 skipping to change at page 25, line 45
exception: should all of the subtags in a grandfathered tag become exception: should all of the subtags in a grandfathered tag become
valid subtags in the IANA registry, then the grandfathered tag valid subtags in the IANA registry, then the grandfathered tag
MUST be marked as redundant. Note that this will not affect MUST be marked as redundant. Note that this will not affect
language tags that match the grandfathered tag, since these tags language tags that match the grandfathered tag, since these tags
will now match valid generative subtag sequences. For example, if will now match valid generative subtag sequences. For example, if
the subtag 'gan' in the language tag "zh-gan" were to be the subtag 'gan' in the language tag "zh-gan" were to be
registered as an extended language subtag, then the grandfathered registered as an extended language subtag, then the grandfathered
tag "zh-gan" would be deprecated (but existing content or tag "zh-gan" would be deprecated (but existing content or
implementations that use "zh-gan" would remain valid). implementations that use "zh-gan" would remain valid).
Language tags formed under RFC 3066 that use the region subtag 'CS' 3.4 Registration Procedure for Subtags
were ambiguous, since tags produced before 2003 used that code for
the (now dissolved) country Czechoslovakia. ISO 3166 assigned this
code to the country Serbia and Montenegro in 2003 and this draft
makes that the canonical value for this subtag. To form a language
tag for the region Czechoslovakia, the UN M.49 code '200' is included
in the registry. As a practical matter, applications that encounter
the RFC 3066 tag "cs-CS" or "sk-CS" MAY wish to convert that to
"cs-200" or "sk-200" (or use one of the successor region subtags,
such as 'CZ' or 'SK'), since that is the most likely interpretation.
3.3 Registration Procedure for Subtags
The procedure given here MUST be used by anyone who wants to use a The procedure given here MUST be used by anyone who wants to use a
subtag not currently in the IANA Language Subtag Registry. subtag not currently in the IANA Language Subtag Registry.
Only primary language and variant subtags will be considered for Only subtags of type 'language' and 'variant' will be considered for
independent registration. (Subtags required for stability and independent registration of new subtags. Handling of subtags
subtags required to keep the registry synchronized with ISO 639, ISO required for stability and subtags required to keep the registry
15924, ISO 3166, and UN M.49 within the limits defined by this synchronized with ISO 639, ISO 15924, ISO 3166, and UN M.49 within
document are the only exceptions to this. See Section 3.2.) the limits defined by this document are described in Section 3.2.
Stability provisions are described in Section 3.3.
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", "note", or "recommended prefix" fields in a for the "Description", "Comments", "Deprecated", or "Recommended-
subtag's record as described in Figure 2. Changes to all other Prefix" fields in a subtag's record as described in Figure 7.
fields in the IANA registry are NOT permitted. Changes to all other fields in the IANA registry are NOT permitted.
If registering a new language subtag, the process starts by filling Registering a new subtag or requesting modifications to an existing
out the registration form reproduced below. Note that each response tag or subtag starts with the requster filling out the registration
is not limited in size and should take the room necessary to form reproduced below. Note that each response is not limited in
adequately describe the registration. size and should take the room necessary to adequately describe the
registration. The fields in the "Record Requested" section SHOULD
follow the requirements in Section 3.1.
LANGUAGE SUBTAG REGISTRATION FORM LANGUAGE SUBTAG REGISTRATION FORM
1. Name of requester: 1. Name of requester:
2. E-mail address of requester: 2. E-mail address of requester:
3. Subtag to be registered: 3. Record Requested:
4. Type of Registration:
[ ] language
[ ] variant
5. Description of subtag (in English or transcribed into ASCII):
6. Intended meaning of the subtag:
7. Recommended prefix(es) of subtag (for variants):
8. Native name of the language or variation (transcribed into ASCII):
9. Reference to published description of the language (book or article):
10. Any other relevant information:
Figure 4 Type:
Subtag:
Description:
Recommended-Prefix:
Canonical:
Deprecated:
Suppress-Script:
Comments:
4. Intended meaning of the subtag:
5. Reference to published description
of the language (book or article):
6. Any other relevant information:
Figure 5
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. Requests to be added be submitted to IANA. (This is an open list. Requests to be added
should be sent to <ietf-languages-request@iana.org>.) should be sent to <ietf-languages-request@iana.org>.)
Variant subtags are generally registered for use with a particular Variant subtags are generally registered for use with a particular
range of language tags. For example, the subtag 'boont' is intended range of language tags. For example, the subtag 'scouse' 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 "en", since Boontling is a dialect of English. Thus the subtag "en", since Scouse is a dialect of English. Thus the subtag
subtag 'boont' could be included in tags such as "en-Latn-boont" or 'scouse' could be included in tags such as "en-Latn-scouse" or "en-
"en-US-boont". This information is stored in the "recommended GB-scouse". This information is stored in the "Recommended-Prefix"
prefix" field in the registry and MUST be provided in the field in the registry. Variant registration requests are REQUIRED to
registration form. include at least one "Recommended-Prefix" field in the registration
form.
Any subtag MAY be incorporated into a variety of language tags, Any subtag MAY be incorporated into a variety of language tags,
according to the rules of Section 2.1, including tags that do not according to the rules of Section 2.1, including tags that do not
match any of the recommended prefixes of the registered subtag. match any of the recommended prefixes of the registered subtag.
(Note that this is probably a poor choice.) This makes validation (Note that this is probably a poor choice.) This makes validation
simpler and thus more uniform across implementations, and does not simpler and thus more uniform across implementations, and does not
require the registration of a separate subtag for the same purpose require the registration of a separate subtag for the same purpose
and meaning but a different recommended prefix. and meaning but a different recommended prefix.
The recommended prefixes for a given registered subtag will be The recommended prefixes for a given registered subtag will be
skipping to change at page 29, line 14 skipping to change at page 27, line 34
prefix. prefix.
Requests to add a recommended prefix to a subtag that imply a Requests to add a recommended prefix to a subtag that imply a
different semantic meaning will probably be rejected. For example, a different semantic meaning will probably be rejected. For example, a
request to add the prefix "de" to the subtag 'nedis' so that the tag request to add the prefix "de" to the subtag 'nedis' so that the tag
"de-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
registered written or transcribed into the Latin script; it may also
include a description in a non-Latin script. Non-ASCII characters
must be escaped using the syntax described in Section 3.1. The
'Description' field is used for identification purposes and should
not be taken to represent the actual native name of the language or
variation or to be in any particular language.
While the 'Description' field itself is not guaranteed to be stable
and errata corrections may be undertaken from time to time, attempts
to provide translations or transcriptions of entries in the registry
itself will probably be frowned upon by the community or rejected
outright, as changes of this nature may impact the provisions in
Section 3.3.
The Language Subtag Reviewer is responsible for responding to The Language Subtag Reviewer is responsible for responding to
requests for the registration of subtags through the registration requests for the registration of subtags through the registration
process and is appointed by the IESG. process and is appointed by the IESG.
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 request to iana@iana.org, or rejects it because either forwards the record to be inserted or modified to
of significant objections raised on the list or due to problems with iana@iana.org according to the procedure described in Section 3.2, or
constraints in this document (which should be explicitly cited). The rejects the request because of significant objections raised on the
reviewer may also extend the review period in two week increments to list or due to problems with constraints in this document (which
permit further discussion. The reviewer must indicate on the list should be explicitly cited). The reviewer may also extend the review
whether the registration has been accepted, rejected, or extended period in two week increments to permit further discussion. The
following each two week period. reviewer must indicate on the list whether the registration has been
accepted, rejected, or extended following each two week period.
Note that the reviewer can raise objections on the list if he or she Note that the reviewer can raise objections on the list if he or she
so desires. The important thing is that the objection must be made so desires. The important thing is that the objection must be made
publicly. 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 reviewer may be appealed to the IESG [RFC 2028] Decisions made by the reviewer may be appealed to the IESG [RFC 2028]
[10] under the same rules as other IETF decisions [RFC 2026] [21]. [9] under the same rules as other IETF decisions [RFC 2026] [8].
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 of registrations follow the same procedure as registrations. Updates or changes to existing records, including previous
The subtag reviewer decides whether to allow a new registrant to registrations, follow the same procedure as new registrations. The
update a registration made by someone else; normally objections by Language Subtag Reviewer decides whether there is consensus to update
the original registrant would carry extra weight in such a decision. the registration following the two week review period; normally
objections by the original registrant will 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 the canonical will not be removed from the registry and will remain the canonical
method of referring to a specific language or variant. This method of referring to a specific language or variant. This
provision does not apply to grandfathered tags, which may become provision does not apply to grandfathered tags, which may become
deprecated due to registration of subtags. For example, the tag deprecated due to registration of subtags. For example, the tag
"i-navajo" is deprecated in favor of the ISO 639-1 based subtag 'nv'. "i-navajo" is deprecated in favor of the ISO 639-1 based subtag 'nv'.
Note: The purpose of the "published description" in the registration Note: The purpose of the "published description" in the registration
form is intended as an aid to people trying to verify whether a form is intended as an aid to people trying to verify whether a
skipping to change at page 30, line 18 skipping to change at page 29, line 7
particular subtag refers to. In most cases, reference to an particular subtag refers to. In most cases, reference to an
authoritative grammar or dictionary of that language will be useful; authoritative grammar or dictionary of that language will be useful;
in cases where no such work exists, other well known works describing in cases where no such work exists, other well known works describing
that language or in that language may be appropriate. The subtag that language or in that language may be appropriate. The subtag
reviewer decides what constitutes "good enough" reference material. reviewer decides what constitutes "good enough" reference material.
This requirement is not intended to exclude particular languages or This requirement is not intended to exclude particular languages or
dialects due to the size of the speaker population or lack of a dialects due to the size of the speaker population or lack of a
standardized orthography. Minority languages will be considered standardized orthography. Minority languages will be considered
equally on their own merits. equally on their own merits.
3.4 Extensions and Extensions Namespace 3.5 Possibilities for Registration
Possibilities for registration of subtags or information about
subtags include:
o Primary language subtags for languages not listed in ISO 639 that
are not variants of any listed or registered language can be
registered. At the time this document was created there were no
examples of this form of subtag. Before attempting to register a
language subtag, there MUST be an attempt to register the language
with ISO 639. No language subtags will be registered for codes
that exist in ISO 639-1 or ISO 639-2, which are under
consideration by the ISO 639 maintenance or registration
authorities, or which have never been attempted for registration
with those authorities. If ISO 639 has previously rejected a
language for registration, it is reasonable to assume that there
MUST be additional very compelling evidence of need before it will
be registered in the IANA registry (to the extent that it is very
unlikely that any subtags will be registered of this type).
o Dialect or other divisions or variations within a language, its
orthography, writing system, regional or historical usage,
transliteration or other transformation, or distinguishing
variation may be registered as variant subtags. An example is the
'scouse' subtag (the Scouse dialect of English).
o The addition or maintenance of fields (generally of an
informational nature) in Tag or Subtag records as described in
Section 3.1 and subject to the stability provisions in
Section 3.3. This includes descriptions, recommended prefixes,
comments, deprecation of obsolete items, or the addition of script
or extlang information to primary language subtags.
This document leaves the decision on what subtags or changes to
subtags are appropriate (or not) to the registration process
described in Section 3.4.
Note: four character primary language subtags are reserved to allow
for the possibility of alpha4 codes in some future addition to the
ISO 639 family of standards.
ISO 639 defines a maintenance agency for additions to and changes in
the list of languages in ISO 639. This agency is:
International Information Centre for Terminology (Infoterm)
Aichholzgasse 6/12, AT-1120
Wien, Austria
Phone: +43 1 26 75 35 Ext. 312 Fax: +43 1 216 32 72
ISO 639-2 defines a maintenance agency for additions to and changes
in the list of languages in ISO 639-2. This agency is:
Library of Congress
Network Development and MARC Standards Office
Washington, D.C. 20540 USA
Phone: +1 202 707 6237 Fax: +1 202 707 0115
URL: http://www.loc.gov/standards/iso639
The maintenance agency for ISO 3166 (country codes) is:
ISO 3166 Maintenance Agency
c/o International Organization for Standardization
Case postale 56
CH-1211 Geneva 20 Switzerland
Phone: +41 22 749 72 33 Fax: +41 22 749 73 49
URL: http://www.iso.org/iso/en/prods-services/iso3166ma/index.html
The registration authority for ISO 15924 (script codes) is:
Unicode Consortium Box 391476
Mountain View, CA 94039-1476, USA
URL: http://www.unicode.org/iso15924
The Statistics Division of the United Nations Secretariat maintains
the Standard Country or Area Codes for Statistical Use and can be
reached at:
Statistical Services Branch
Statistics Division
United Nations, Room DC2-1620
New York, NY 10017, USA
Fax: +1-212-963-0623
E-mail: statistics@un.org
URL: http://unstats.un.org/unsd/methods/m49/m49alpha.htm
3.6 Extensions and Extensions Namespace
Extension subtags are those introduced by single-letter subtags other Extension subtags are those introduced by single-letter subtags other
than 'x-'. They are reserved for the generation of identifiers which than 'x-'. They are reserved for the generation of identifiers which
contain a language component, and are compatible with applications contain a language component, and are compatible with applications
that process language tags according to this specification. For understand language tags. For example, they might be used to define
example, they might be used to define locale identifiers, which are locale identifiers, which are generally based on language.
generally based on language.
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 may be created using single-letter subtags in the applications that may be created using single-letter subtags in the
future. In addition, defining a mechanism for maintaining future. In addition, defining a mechanism for maintaining single-
single-letter subtags will lend to the stability of this document by letter subtags will lend to the stability of this document by
reducing the likely need for future revisions or updates. reducing the likely need for future revisions or updates.
IANA will maintain a registry of allocated single-letter subtags.
This registry contains the following information: letter identifier;
name; purpose; RFC defining the subtag namespace and its use; and the
name, URL, and email address of the maintaining authority.
Allocation of a single-letter subtag shall take the form of an RFC Allocation of a single-letter subtag shall take the form of an RFC
defining the name, purpose, processes, and procedures for maintaining defining the name, purpose, processes, and procedures for maintaining
the subtags. The maintaining or registering authority, including the subtags. The maintaining or registering authority, including
name, contact email, discussion list email, and URL location of the name, contact email, discussion list email, and URL location of the
registry must be indicated clearly in the RFC. The RFC MUST specify registry must be indicated clearly in the RFC. The RFC MUST specify
each of the following: or include each 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 govern 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. specify that case is not significant and that subtags MUST NOT
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
registration form reproduced in this section (below) to be used in
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-letter (singleton)
subtags. This registry will use the record-jar format described by
the ABNF in Section 3.1. Upon publication of an extension as an RFC,
the maintaining authority defined in the RFC must forward this
registration form to iesg@ietf.org, who will forward the request to
iana@iana.org. The maintaining authority of 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 line "LANGUAGE TAG
EXTENSION UPDATE" whenever content changes. Only the 'Comments',
'Contact_Email', 'Mailing_List', and 'URL' fields may be modified in
these updates.
Failure to maintain this record, the corresponding registry, or meet
other conditions imposed by this section of this document may be
appealed to the IESG [RFC 2028] [9] under the same rules as other
IETF decisions (see [8]) and may result in the authority to maintain
the extension being withdrawn or reassigned by the IESG.
%%
Identifier:
Description:
Comments:
Added:
RFC:
Authority:
Contact_Email:
Mailing_List:
URL:
%%
Figure 6: Format of Records in the Language Tag Extensions Registry
'Identifier' contains the single letter subtag (singleton) assigned
to the extension. The Internet-Draft submitted to define the
extension should specific which letter to use, although the IESG may
change the assignment when approving the RFC.
'Description' contains the name and description of the extension.
'Comments' is an optional field and may contain a broader description
of the extension.
'Added' contains the date the RFC was published in the "full-date"
format specified in RFC 3339 [14]. For example: 2004-06-28
represents June 28, 2004, in the Gregorian calendar.
'RFC' contains the RFC number assigned to the extension.
'Authority' contains the name of the maintaining authority for the
extension.
'Contact_Email' contains the email address used to contact the
maintaining authority.
'Mailing_List' contains the URL or subscription email address of the
mailing list used by the maintaining authority.
'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
skipping to change at page 32, line 5 skipping to change at page 33, line 36
most significant information be in the most significant (left-most) most significant information be in the most significant (left-most)
subtags, and that the specification gracefully handle truncated subtags, and that the specification gracefully handle truncated
subtags. 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 that the language tag not contain extensions not
supported by that protocol. In addition, it should be noted that supported by that protocol. In addition, it should be noted that
some protocols may impose upper limits on the length of the strings some protocols may impose upper limits on the length of the strings
used to store or transport the language tag. used to store or transport the language tag.
4. Security Considerations 3.7 Conversion of the RFC 3066 Language Tag Registry
Upon publication of this document as a BCP, the existing IANA
language tag registry must be converted into the new subtag registry.
This section defines the process for performing this conversion.
The impact on the IANA maintainers of the registry of this conversion
will be a small increase in the frequency of new entries. The
initial set of records represents no impact on IANA, since the work
to create it will be performed externally (as defined in this
section). Future work will be limited to inserting or replacing
whole records preformatted for IANA by the Language Subtag Reviewer.
When this document is published, an email will be sent by the
chair(s) of the LTRU working group to the LTRU and ietf-languages
mail lists advising of the impending conversion of the registry. In
that notice, the chair(s) will provide a URL whose referred content
is the proposed IANA Language Subtag Registry following conversion.
There will be a Last Call period of not less than four weeks for
comments and corrections to be discussed on the
ietf-languages@iana.org mail list. Changes as a result of comments
will not restart the Last Call period. At the end of the period, the
chair(s) will forward the URL to IANA, which will post the new
registry on-line.
Tags that are currently deprecated will be maintained as
grandfathered entries. The record for the grandfathered entry will
contain a 'Deprecated' field with the most appropriate date that can
be determined for when the record was deprecated. The 'Comments'
field will contain the reason for the deprecation. The 'Canonical'
field will contain the tag that replaces the value. For example, the
tag "art-lojban" is deprecated and will be placed in the
grandfathered section. It's 'Deprecated' field will contain the
deprecation date and 'Canonical' field the value "jbo".
Tags that are not deprecated that consist entirely of subtags that
are valid under this document and which have the correct form and
format for tags defined by this document are superseded by this
document. Such tags are placed in records of type 'redundant' in the
registry. For example, "zh-Hant" is now defined by this document.
Tags that are not deprecated and which contain subtags which are
consistent with registration under the guidelines in this document
will have a new subtag registration created for each eligible subtag.
If all of the subtags in the original tag are fully defined by the
resulting registrations or by this document, then the original tag is
superseded by this document. Such tags are placed in the 'redundant'
section of the registry. For example, "en-boont" will result in a
new subtag 'boont' and the RFC 3066 registered tag "en-boont" placed
in the redundant section of the registry.
Tags that contain one or more subtags that do not match the valid
registration pattern and which are not otherwise defined by this
document will have records of type 'grandfathered' created in the
registry.
There will be a reasonable period in which the community may comment
on the proposed list entries, which SHALL be no less than four weeks
in length. At the completion of this period, the chair(s) will
notify iana@iana.org and the ltru and ietf-languages mail lists that
the task is complete and forward the necessary materials to IANA for
publication.
Registrations that are in process under the rules defined in RFC 3066
MAY be completed under the former rules, at the discretion of the
language tag reviewer. Any new registrations submitted after the
request for conversion of the registry MUST be rejected.
All existing RFC 3066 language tag registrations will be maintained
in perpetuity.
Users of tags that are grandfathered should consider registering
appropriate subtags in the IANA subtag registry (but are not required
to).
Where two subtags have the same meaning, the priority of which to
make canonical SHALL be the following:
o As of the date of acceptance of this document as a BCP, if a code
exists in the associated ISO standard and it is not deprecated or
withdrawn as of that date, then it has priority.
o Otherwise, the earlier-registered tag in the associated ISO
standard has priority.
UN numeric codes assigned to 'macro-geographical (continental)' or
sub-regions not associated with an assigned ISO 3166 alpha-2 code are
defined in the IANA registry and are valid for use in language tags.
These codes MUST be added to the initial version of the registry.
The UN numeric codes for 'economic groupings' or 'other groupings',
and the alphanumeric codes in Appendix X of the UN document MUST NOT
be added to the registry.
When creating records for ISO 639, ISO 15924, ISO3166, and UN M.49
codes, the following criteria SHALL be applied to the inclusion,
canonical mapping, and deprecation of codes:
For each standard, the date of the standard referenced in RFC 1766 is
selected as the starting date. Codes that were valid on that date in
the selected standard are added to the registry. Codes that were
previously assigned by were vacated or withdrawn before that date are
not added to the registry. For each successive change to the
standard, any additional assignments are added to the registry.
Values that are withdrawn are marked as deprecated, but not removed.
Changes in meaning or assignment of a subtag are permitted during
this process (cf. 'CS'). This continues up to the date that this
document was adopted. The resulting set of records is added to the
registry. Future changes or additions to this portion of the
registry are governed by the provisions of this document.
4. Formation and Processing of Language Tags
This section addresses how to use the registry with the language tag
format to choose, form and process language tags.
4.1 Choice of Language Tag
One may occasionally be faced with several possible tags for the same
body of text.
Interoperability is best served when all users use the same language
tag in order to represent the same language. If an application has
requirements that make the rules here inapplicable, then that
application risks damaging interoperability. It is strongly
RECOMMENDED that users not define their own rules for language tag
choice.
Of particular note, many applications can benefit from the use of
script subtags in language tags, as long as the use is consistent for
a given context. Script subtags were not formally defined in RFC
3066 and their use may affect matching and subtag identification by
implementations of RFC 3066, as these subtags appear between the
primary language and region subtags. For example, if a user requests
content in an implementation of Section 2.5 of RFC 3066 [23] using
the language range "en-US", content labeled "en-Latn-US" will not
match the request. Therefore it is important to know when script
subtags will customarily be used and when they should not be used.
Extended language subtags (type 'extlang' in the registry, see
Section 3.1) also appear between the primary language and region
subtags and are reserved for future standardization. Applications
may benefit from their judicious use in forming language tags in the
future and similar recommendations are expected to apply to their use
as apply to script subtags.
Standards, protocols and applications that reference this document
normatively but apply different rules to the ones given in this
section MUST specify how the procedure varies from the one given
here.
The choice of subtags used to form a language tag should be guided by
the following rules:
1. Use as precise a tag as possible, but no more specific than is
justified. Avoid using subtags that are not important for
distinguishing content in an application.
* For example, 'de' might suffice for tagging an email written
in German, while "de-CH-1996" is probably unnecessarily
precise for such a task.
2. The script subtag SHOULD NOT be used to form language tags unless
the script adds some distinguishing information to the tag. The
field 'Suppress-Script' in the primary language record in the
registry indicates which script subtags do not add distinguishing
information for most applications.
* For example, the subtag 'Latn' should not be used with the
primary language 'en' because nearly all English documents are
written in the Latin script and it adds no distinguishing
information. However, if a document were written in English
mixing Latin script with another script such as Braille
('Brai'), then it may be appropriate to choose to indicate
both scripts to aid in content selection, such as the
application of a stylesheet.
3. If a subtag has a 'Canonical' field in its registry entry, the
canonical subtag SHOULD be used to form the language tag in
preference to any of its aliases.
* For example, use 'he' for Hebrew in preference to 'iw'.
4. The 'und' (Undetermined) primary language subtag SHOULD NOT be
used to label content, even if the language is unknown. Omitting
the language tag altogether is preferred to using a tag with a
primary language subtag of 'und'. The 'und' subtag may be useful
for protocols that require a language tag to be provided. The
'und' subtag may also be useful when matching language tags in
certain situations.
5. The 'mul' (Multiple) primary language subtag SHOULD NOT be used
whenever the protocol allows the separate tags for multiple
languages, as is the case for the Content-Language header in
HTTP. The 'mul' subtag conveys little useful information:
content in multiple languages should individually tag the
languages where they appear or otherwise indicate the actual
language in preference to the 'mul' subtag.
6. The same variant subtag SHOULD NOT be used more than once within
a language tag.
* For example, do not use "en-GB-scouse-scouse".
To ensure consistent backward compatibility, this document contains
several provisions to account for potential instability in the
standards used to define the subtags that make up language tags.
These provisions mean that no language tag created under the rules in
this document will become obsolete. In addition, tags that are in
canonical form will always be in canonical form.
4.2 Meaning of the Language Tag
The language tag always defines a language as spoken (or written,
signed or otherwise signaled) by human beings for communication of
information to other human beings. Computer languages such as
programming languages are explicitly excluded.
If a language tag B contains language tag A as a prefix, then B is
typically "narrower" or "more specific" than A. For example, "zh-
Hant-TW" is more specific than "zh-Hant".
This relationship is not guaranteed in all cases: specifically,
languages that begin with the same sequence of subtags are NOT
guaranteed to be mutually intelligible, although they may be. For
example, the tag "az" shares a prefix with both "az-Latn"
(Azerbaijani written using the Latin script) and "az-Cyrl"
(Azerbaijani written using the Cyrillic script). A person fluent in
one script may not be able to read the other, even though the text
might be identical. Content tagged as "az" most probably is written
in just one script and thus might not be intelligible to a reader
familiar with the other script.
The relationship between the tag and the information it relates to is
defined by the standard describing the context in which it appears.
Accordingly, this section can only give possible examples of its
usage.
o For a single information object, the associated language tags
might be interpreted as the set of languages that is required for
a complete comprehension of the complete object. Example: Plain
text documents.
o For an aggregation of information objects, the associated language
tags could be taken as the set of languages used inside components
of that aggregation. Examples: Document stores and libraries.
o For information objects whose purpose is to provide alternatives,
the associated language tags could be regarded as a hint that the
content is provided in several languages, and that one has to
inspect each of the alternatives in order to find its language or
languages. In this case, the presence of multiple tags might not
mean that one needs to be multi-lingual to get complete
understanding of the document. Example: MIME multipart/
alternative.
o In markup languages, such as HTML and XML, language information
can be added to each part of the document identified by the markup
structure (including the whole document itself). For example, one
could write <span lang="fr">C'est la vie.</span> inside a
Norwegian document; the Norwegian-speaking user could then access
a French-Norwegian dictionary to find out what the marked section
meant. If the user were listening to that document through a
speech synthesis interface, this formation could be used to signal
the synthesizer to appropriately apply French text-to-speech
pronunciation rules to that span of text, instead of applying the
inappropriate Norwegian rules.
4.3 Canonicalization of Language Tags
Since a particular language tag may be used in many processes,
language tags SHOULD always be created or generated in a canonical
form.
A language tag is in canonical form when:
1. The tag is well-formed according the rules in Section 2.1 and
Section 2.2.
2. None of the subtags in the language tag has a canonical_value
mapping in the IANA registry (see Section 3.1). Subtags with a
canonical_value mapping MUST be replaced with their mapping in
order to canonicalize the tag.
3. If more than one extension subtag sequence exists, the extension
sequences are ordered into case-insensitive ASCII order by
singleton subtag.
Example: The language tag "en-A-aaa-B-ccc-bbb-x-xyz" is in canonical
form, while "en-B-ccc-bbb-A-aaa-X-xyz" is well-formed but not in
canonical form.
Example: The language tag "en-NH" (English as used in the New
Hebrides) is not canonical because the 'NH' subtag has a canonical
mapping to 'VU' (Vanuatu).
Note: Canonicalization of language tags does not imply anything about
the use of upper or lowercase letter in subtags as described in
Section 2.1. All comparisons MUST be performed in a case-insensitive
manner.
Note: if the field 'Deprecated' appears in a registry record without
an accompanying 'Canonical' field, then that tag or subtag is
deprecated without a replacement. Validating processors SHOULD NOT
generate tags that include these values, although the values are
canonical when they appear in a language tag.
An extension MUST define any relationships that may exist between the
various subtags in the extension and thus MAY define an alternate
canonicalization scheme for the extension's subtags. Extensions MAY
define how the order of the extension's subtags are interpreted. For
example, an extension could define that its subtags are in canonical
order when the subtags are placed into ASCII order: that is, "en-a-
aaa-bbb-ccc" instead of "en-a-ccc-bbb-aaa". Another extension 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-
aaa-bbb-ccc"). However, extension specifications SHOULD be designed
so that they are tolerant of the typical processes described in
Section 3.6.
4.4 Considerations for Private Use Subtags
Private-use subtags require private agreement between the parties
that intend to use or exchange language tags that use them and great
caution should be used in employing them in content or protocols
intended for general use. Private-use subtags are simply useless for
information exchange without prior arrangement.
The value and semantic meaning of private-use tags and of the subtags
used within such a language tag are not defined by this document.
The use of subtags defined in the IANA registry as having a specific
private use meaning convey more information that a purely private use
tag prefixed by the singleton subtag 'x'. For applications this
additional information may be useful.
For example, the region subtags 'AA', 'ZZ' and in the ranges
'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
great deal of public, interchangeable information about the language
material (that it is Chinese in the simplified Chinese script and is
suitable for some geographic region 'XQ'). While the precise
geographic region is not known outside of private agreement, the tag
conveys far more information than an opaque tag such as "x-someLang",
which contains no information about the language subtag or script
subtag outside of the private agreement.
However, in some cases content tagged with private use subtags may
interact with other systems in a different and possibly unsuitable
manner compared to tags that use opaque, privately defined subtags,
so the choice of the best approach may depend on the particular
domain in question.
5. IANA Considerations
This section deals with the processes and requirements necessary for
IANA to undertake to maintain the rsubtag and extension registries as
defined by this document and in accordance with the requirements of
RFC 2434 [11].
The impact on the IANA maintainers of the two registries defined by
this document will be a small increase in the frequency of new
entries or updates.
Upon adoption of this document, the process described in Section 3.7
will be used to generate the initial Language Subtag Registry. The
initial set of records represents no impact on IANA, since the work
to create it will be performed externally (as defined in that
section). The new registry will be listed under "Language Tags" at
<http://www.iana.org/numbers.html>. The existing directory of
registration forms and RFC 3066 registrations will be relabeled as
"Language Tags (Obsolete)" and maintained (but not added to or
modified).
Future work on the Language Subtag Registry will be limited to
inserting or replacing whole records preformatted for IANA by the
Language Subtag Reviewer as described in Section 3.2 of this
document. Each record will be sent to iana@iana.org with a subject
line indicating whether the enclosed record is an insertion (of a new
record) or a replacment of an existing record which has a Type and
Subtag (or Tag) field that exactly matches the record sent. Records
cannot be deleted from the registry.
The Language Tag Extensions registry will also be generated and sent
to IANA as described in Section 3.6. This registry may contain at
most 25 records and thus changes to this registry are expected to be
very infrequent.
Future work by IANA on the Language Tag Extensions Registry is
limited to two cases. First, the IESG may request that new records
be inserted into this registry from time to time. These requests
will include the record to insert in the exact format described in
Section 3.6. In addition, there may be occasional requests from the
maintaining authority for a specific extension to update the contact
information or URLs in the record. These requests MUST include the
complete, updated record. IANA is not responsible for validating the
information provided, only that it is properly formatted. It should
reasonably be seen to come from the maintaining authority named in
the record present in the registry.
6. Security Considerations
The only security issue that has been raised with language tags since The only security issue that has been raised with language tags since
the publication of RFC 1766, which stated that "Security issues are the publication of RFC 1766 [21], which stated that "Security issues
believed to be irrelevant to this memo", is a concern with language are believed to be irrelevant to this memo", is a concern with
identifiers used in content negotiation - that they may be used to language identifiers used in content negotiation - that they may be
infer the nationality of the sender, and thus identify potential used to infer the nationality of the sender, and thus identify
targets for surveillance. potential targets for surveillance.
This is a special case of the general problem that anything you send This is a special case of the general problem that anything sent is
is visible to the receiving party. It is useful to be aware that visible to the receiving party and possibly to third parties as well.
such concerns can exist in some cases. It is useful to be aware that such concerns can exist in some cases.
The evaluation of the exact magnitude of the threat, and any possible The evaluation of the exact magnitude of the threat, and any possible
countermeasures, is left to each application protocol. countermeasures, is left to each application protocol (see BCP 72,
RFC 3552 [15] for best current practice guidance on security threats
and defenses).
Although the specification of valid subtags for an extension MUST be Although the specification of valid subtags for an extension MUST be
available over the Internet, implementations SHOULD NOT mechanically available over the Internet, implementations SHOULD NOT mechanically
depend on it being always accessible, to prevent denial-of-service depend on it being always accessible, to prevent denial-of-service
attacks. attacks.
5. 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 presentation of language tags should not have any character sets, so the composition of language tags should not have
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 ideographs
as used in Japanese, Chinese, and Korean). When language tags are as used in Japanese, Chinese, and Korean). When language tags are
applied to spans of text, rendering engines may use that information applied to spans of text, rendering engines may use that information
in deciding which font to use in the absence of other information, in deciding which font to use in the absence of other information,
particularly where languages with distinct writing traditions use the particularly where languages with distinct writing traditions use the
same characters. same characters.
6. 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 valid RFC 3066 language tags (including those *Compatibility.* All valid RFC 3066 language tags (including those
in the IANA registry) remain valid in this specification. Thus in the IANA registry) remain valid in this specification. Thus
there is complete backward compatibility of this specification with there is complete backward compatibility of this specification with
existing content. In addition, this document defines language tags existing content. In addition, this document defines language tags
in such as way as to ensure future compatibility, and processors in such as way as to ensure future compatibility, and processors
based solely on the RFC 3066 ABNF (such as those described in XML based solely on the RFC 3066 ABNF (such as those described in XML
Schema version 1.0) will be able to process tags described by this Schema version 1.0 [19]) will be able to process tags described by
document. this document.
*Stability.* Because of the changes in underlying ISO standards, a *Stability.* Because of the changes in underlying ISO standards, a
valid RFC 3066 language tag may become invalid (or have its meaning valid RFC 3066 language tag may become invalid (or have its meaning
change) at a later date. With so much of the world's computing change) at a later date. With so much of the world's computing
infrastructure dependent on language tags, this is simply infrastructure dependent on language tags, this is simply
unacceptable: it invalidates content that may have an extensive unacceptable: it invalidates content that may have an extensive
shelf-life. In this specification, once a language tag is valid, it shelf-life. In this specification, once a language tag is valid, it
remains valid forever. Previously, there was no way to determine remains valid forever. Previously, there was no way to determine
when two tags were equivalent. This specification provides a stable when two tags were equivalent. This specification provides a stable
mechanism for doing so, through the use of canonical forms. These mechanism for doing so, through the use of canonical forms. These
skipping to change at page 35, line 20 skipping to change at page 46, line 20
whole tags, and the burden on the registry of having to supply all of whole tags, and the burden on the registry of having to supply all of
the combinations that people may find useful. the combinations that people may find useful.
Because of the widespread use of language tags, it is potentially Because of the widespread use of language tags, it is potentially
disruptive to have periodic revisions of the core specification, disruptive to have periodic revisions of the core specification,
despite demonstrated need. The extension mechanism provides for a despite demonstrated need. The extension mechanism provides for a
way for independent RFCs to define extensions to language tags. way for independent RFCs to define extensions to language tags.
These extensions have a very constrained, well-defined structure to These extensions have a very constrained, well-defined structure to
prevent extensions from interfering with implementations of language prevent extensions from interfering with implementations of language
tags defined in this document. The document also anticipates tags defined in this document. The document also anticipates
features of ISO 639-3 with the addition of the extlang subtags. The features of ISO 639-3 with the addition of the extended language
use and definition of private use tags has also been modified, to subtags, as well as the possibility of other ISO 639 parts becoming
allow people to move as much information as possible out of private useful for the formation of language tags in the future. The use and
use tags, and into the regular structure. The goal is to definition of private use tags has also been modified, to allow
dramatically reduce the need to produce a revision of this document people to move as much information as possible out of private use
in the future. tags, and into the regular structure. The goal is to dramatically
reduce the need to produce a revision of this document in the future.
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,
defining the rules by which an implementation can claim to be one defining the rules by which an implementation can claim to be one
or the other. or the other.
o Changes the IANA language tag registry to a language subtag
o Replaces the IANA language tag registry with a language subtag
registry that provides a complete list of valid subtags in the registry that provides a complete list of valid subtags in the
IANA registry. This allows for robust implementation and ease of IANA registry. This allows for robust implementation and ease of
maintenance. The language subtag registry becomes the canonical maintenance. The language subtag registry becomes the canonical
source for forming language tags. source for forming language tags.
o Provides a process that guarantees stability of language tags, by o Provides a process that guarantees stability of language tags, by
handling reuse of values by ISO 639, ISO 15924, and ISO 3166 in handling reuse of values by ISO 639, ISO 15924, and ISO 3166 in
the event that they register a previously used value for a new the event that they register a previously used value for a new
purpose. purpose.
o Allows ISO 15924 script code subtags and allows them to be used o Allows ISO 15924 script code subtags and allows them to be used
generatively. Adds the concept of a variant subtag and allows generatively. Adds the concept of a variant subtag and allows
variants to be used generatively. Adds the ability to use a class variants to be used generatively. Adds the ability to use a class
of UN tags as regions. of UN tags as regions.
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.
Ed Note: The following items are provided for the convenience of Ed Note: The following items are provided for the convenience of
reviewers and will be removed from the final document. reviewers and will be removed from the final document.
Changes between draft-phillips-langtags-10 and this version are: Changes between draft-ietf-ltru-registry-00 and this version are:
o Expunged the terminology "language range", since that section goes
with matching (A.Phillips, M.Davis)
o Added text describing the handling of existing RFC 3066 registry
entries that were deprecated prior to the adoption of this
document. These tags are now grandfathered. (A.Phillips,
D.Ewell)
o Modified the conversion rules for the registry (Appendix C) to
refer to the chairs, the LTRU mail list and so forth (A.Phillips)
o Added text to allow tags and subtags to be deprecated using the
canonical value "--". This is applied to codes withdrawn by ISO
639 MA and ISO 3166 MA, for example. (F.Ellerman, D.Ewell)
7. References o Updated the ABNF for singleton to make it conform to RFC 2234 and
pass the Fenner parser (F.Ellermann)
[1] International Organization for Standardization, "ISO o Split the references into informative and normative lists.
639-1:2002, Codes for the representation of names of languages Eliminated dead references carried forward from previous versions
-- Part 1: Alpha-2 code", ISO Standard 639, 2002. of this document. (A.Phillips)
o Added a reference to RFC 3552 (BCP 72) to the Security
Considerations section (I.McDonald)
o Modified the first sentence in Section 2.1.1 from "on the number
of size of subtags in a Language Tag" to be proper English and
convey more meaning. (A.Phillips)
o Various examples that used the variant 'boont' were changes to use
the variant 'scouse' instead. (J.Cowan)
o Added an additional example ("en-a-bbb-x-a-ccc") to the extension/
singleton rules in Section 2.2.6 to illustrate that singletons can
recur in private use sequences (A.Phillips)
o Modified the sentence describing the possibilities for variant
registration (see Section 3.5) to include transliterations and
other transformations per discussion on the list. (M.T. Carrasco
Benitez)
o Converted the format of the registry to record-jar format. This
subtantially replaces section 3.1 (R.Presuhn)
o Subtantially revised the rules for registry creation to reflect
the Date A/B boundaries on adopting ISO 3166 codes (J.Cowan)
o Modified the registration process section and form to deal with
both new additions and revisions of records, as well as making
life easier on the Subtag Reviewer by matching the fields to the
registry format. (A.Phillips)
o Changed the reference to RFC 2234 to RFC 2234bis (recently
adopted). (S.Hollenbeck)
o Modifications to make this document conformant with RFC 3978
(recently adopted). (R.Presuhn)
o Added an informative reference to XML Schema 1.0 Part 2: Second
Edition in this section. (J.Morfin)
o Expanded the jargon-ish 'extlang' to "extended language" in this
section. (J.Morfin)
o Corrected an egregious error in the ABNF (%x6A -> %x5A in one of
the ranges) (A.Phillips)
o Split Maintenance of the Registry from Format of the Registry
(A.Phillips)
o Revision of section Section 3.4 to make it consistent with the new
section Section 3.2. (A.Phillips)
o Separated IANA Considerations section from the registry definition
and registration procedures. ()
o Added additional choice information dealing with scripts and
extlangs. These items were also moved to a new section following
the registry format because of interdependence.
o Updated the IANA Considerations section.
o Added appeal and maintenance requirements to the extensions
Section 3.6 section. (A.Phillips)
o Added an additional bullet point to Section 3.5 enumerating the
changes that can be registered to a record (previously we only
listed the options for new subtags). (A.Phillips)
o Added the phrase ", as well as the possibility of other ISO 639
parts becoming useful for the formation of language tags in the
future" to this section in anticipation of revising the ABNF to
allow for the possibility of ISO 639-6 being used in language tags
in a future revision of this document. (D.Garside)
o Added the concept of 'Suppress-Script' to Section 4.1, as well as
to the registry format in Section 3.1, Section 3.3 and
Section 3.2. (many)
o Added text requiring the I-D that defines an extension to choose a
letter (and allowing the IESG to change it if necessary).
(D.Ewell?)
o Removed the ABNF notes from the text about case insensitivity
(F.Ellermann)
o Removed the second, rather repetitive reference to Appendix B in
Section 2.1 (A.Phillips)
o Fixed missing whitesapce in Section 2.1 (F.Ellermann)
o Changed "empty" to "omitted" in Section 2.2.1 (F.Ellermann)
o Changed the intro to Section 2.2.1 and otherwise tugged at that
section to deal with i-* grandfathered items. (F.Ellermann)
o Reserved alpha4 language subtags for future standardization.
(D.Garside)
o Incorporate changes to be consistent with RFC 3978, including the
new xml2rfc processor. Note that this has an effect on the ABNF,
since some of the comments were too wide previously (comments were
revised to fit the 72 character maximum). (S.Hollenbeck)
o Remove the Latin-1 restriction on the 'Description' field.
Provide guidance for registration of content, including a
requirement for at least one representation in the Latin script.
(F.Ellermann, A.Phillips)
o Make the variant subtlety less so. (F.Ellermann)
o Various 'you' removals and cleanup (M.Davis)
o Inserted additional non-normative caveat about the 'MUL' subtag
(A.Phillips)
o Various editorial edits (J.Cowan)
o Use normative language when giving permission to not store long
language tags in Section 2.1.1. (J.Cowan)
9. References
9.1 Normative References
[1] International Organization for Standardization, "ISO 639-
1:2002, Codes for the representation of names of languages --
Part 1: Alpha-2 code", ISO Standard 639, 2002.
[2] International Organization for Standardization, "ISO 639-2:1998 [2] International Organization for Standardization, "ISO 639-2:1998
- Codes for the representation of names of languages -- Part 2: - Codes for the representation of names of languages -- Part 2:
Alpha-3 code - edition 1", August 1988. Alpha-3 code - edition 1", August 1988.
[3] ISO TC46/WG3, "ISO 15924:2003 (E/F) - Codes for the [3] ISO TC46/WG3, "ISO 15924:2003 (E/F) - Codes for the
representation of names of scripts", January 2004. representation of names of scripts", January 2004.
[4] International Organization for Standardization, "Codes for the [4] International Organization for Standardization, "Codes for the
representation of names of countries, 3rd edition", representation of names of countries, 3rd edition",
ISO Standard 3166, August 1988. ISO Standard 3166, August 1988.
[5] Statistical Division, United Nations, "Standard Country or Area [5] Statistical Division, United Nations, "Standard Country or Area
Codes for Statistical Use", UN Standard Country or Area Codes Codes for Statistical Use", UN Standard Country or Area Codes
for Statistical Use, Revision 4 (United Nations publication, for Statistical Use, Revision 4 (United Nations publication,
Sales No. 98.XVII.9, June 1999. Sales No. 98.XVII.9, June 1999.
[6] ISO 639 Joint Advisory Committee, "ISO 639 Joint Advisory [6] International Organization for Standardization, "ISO/IEC 10646-
Committee: Working principles for ISO 639 maintenance", March 1:2000. Information technology -- Universal Multiple-Octet
2000, Coded Character Set (UCS) -- Part 1: Architecture and Basic
<http://www.loc.gov/standards/iso639-2/iso639jac_n3r.html>. Multilingual Plane and ISO/IEC 10646-2:2001. Information
technology -- Universal Multiple-Octet Coded Character Set
[7] Hardcastle-Kille, S., "Mapping between X.400(1988) / ISO 10021 (UCS) -- Part 2: Supplementary Planes, as, from time to time,
and RFC 822", RFC 1327, May 1992. amended, replaced by a new edition or expanded by the addition
of new parts", 2000.
[8] Borenstein, N. and N. Freed, "MIME (Multipurpose Internet Mail [7] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Extensions) Part One: Mechanisms for Specifying and Describing Specifications: ABNF", draft-crocker-abnf-rfc2234bis-00 (work
the Format of Internet Message Bodies", RFC 1521, September in progress), March 2005.
1993.
[9] Alvestrand, H., "Tags for the Identification of Languages", [8] Bradner, S., "The Internet Standards Process -- Revision 3",
RFC 1766, March 1995. BCP 9, RFC 2026, October 1996.
[10] Hovey, R. and S. Bradner, "The Organizations Involved in the [9] Hovey, R. and S. Bradner, "The Organizations Involved in the
IETF Standards Process", BCP 11, RFC 2028, October 1996. IETF Standards Process", BCP 11, RFC 2028, October 1996.
[11] Bradner, S., "Key words for use in RFCs to Indicate Requirement [10] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[12] Freed, N. and K. Moore, "MIME Parameter Value and Encoded Word [11] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Extensions: Character Sets, Languages, and Continuations", Considerations Section in RFCs", BCP 26, RFC 2434,
RFC 2231, November 1997. October 1998.
[13] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [12] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO 10646",
Specifications: ABNF", RFC 2234, November 1997. RFC 2781, February 2000.
[14] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform [13] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of
Resource Identifiers (URI): Generic Syntax", RFC 2396, August Understanding Concerning the Technical Work of the Internet
1998. Assigned Numbers Authority", RFC 2860, June 2000.
[15] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA [14] Klyne, G. and C. Newman, "Date and Time on the Internet:
Considerations Section in RFCs", BCP 26, RFC 2434, October Timestamps", RFC 3339, July 2002.
1998.
[16] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., [15] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on
Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol -- Security Considerations", BCP 72, RFC 3552, July 2003.
HTTP/1.1", RFC 2616, June 1999.
[17] Carpenter, B., Baker, F. and M. Roberts, "Memorandum of 9.2 Informative References
Understanding Concerning the Technical Work of the Internet
Assigned Numbers Authority", RFC 2860, June 2000.
[18] Alvestrand, H., "Tags for the Identification of Languages", [16] ISO 639 Joint Advisory Committee, "ISO 639 Joint Advisory
BCP 47, RFC 3066, January 2001. Committee: Working principles for ISO 639 maintenance",
March 2000,
<http://www.loc.gov/standards/iso639-2/iso639jac_n3r.html>.
[19] Yergeau, F., "UTF-8, a transformation format of ISO 10646", [17] Raymond, E., "The Art of Unix Programming", 2003.
STD 63, RFC 3629, November 2003.
[20] Klyne, G. and C. Newman, "Date and Time on the Internet: [18] Bray (et al), T., "Extensible Markup Language (XML) 1.0",
Timestamps", RFC 3339, July 2002. 02 2004.
[21] <http://www.ietf.org/rfc/rfc2026.txt> [19] Biron, P., Ed. and A. Malhotra, Ed., "XML Schema Part 2:
Datatypes Second Edition", 10 2004, <
http://www.w3.org/TR/xmlschema-2/>.
[20] Unicode Consortium, "The Unicode Consortium. The Unicode
Standard, Version 4.1.0, defined by: The Unicode Standard,
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.
[21] Alvestrand, H., "Tags for the Identification of Languages",
RFC 1766, March 1995.
[22] Freed, N. and K. Moore, "MIME Parameter Value and Encoded Word
Extensions: Character Sets, Languages, and Continuations",
RFC 2231, November 1997.
[23] Alvestrand, H., "Tags for the Identification of Languages",
BCP 47, RFC 3066, January 2001.
Authors' Addresses Authors' Addresses
Addison Phillips (editor) Addison Phillips (editor)
Quest Software Quest Software
Email: addison.phillips@quest.com Email: addison.phillips@quest.com
Mark Davis (editor) Mark Davis (editor)
IBM IBM
skipping to change at page 39, line 20 skipping to change at page 53, line 20
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
document and are generally responsible for the success of language document and are generally responsible for the success of language
tags. tags.
The following people (in alphabetical order) contributed to this The following people (in alphabetical order) contributed to this
document or to RFCs 1766 and 3066: document or to RFCs 1766 and 3066:
Glenn Adams, Harald Tveit Alvestrand, Tim Berners-Lee, Marc Blanchet, Glenn Adams, Harald Tveit Alvestrand, Tim Berners-Lee, Marc Blanchet,
Nathaniel Borenstein, Eric Brunner, Sean M. Burke, Jeremy Carroll, Nathaniel Borenstein, Eric Brunner, Sean M. Burke, M.T. Carrasco
John Clews, Jim Conklin, Peter Constable, John Cowan, Mark Crispin, Benitez, Jeremy Carroll, John Clews, Jim Conklin, Peter Constable,
Dave Crocker, Martin Duerst, Frank Ellerman, Michael Everson, Doug John Cowan, Mark Crispin, Dave Crocker, Martin Duerst, Frank
Ewell, Ned Freed, Tim Goodwin, Dirk-Willem van Gulik, Marion Gunn, Ellerman, Michael Everson, Doug Ewell, Ned Freed, Tim Goodwin, Dirk-
Joel Halpren, Elliotte Rusty Harold, Paul Hoffman, Richard Ishida, Willem van Gulik, Marion Gunn, Joel Halpren, Elliotte Rusty Harold,
Olle Jarnefors, Kent Karlsson, John Klensin, Alain LaBonte, Eric Paul Hoffman, Scott Hollenbeck, Richard Ishida, Olle Jarnefors, Kent
Mader, Keith Moore, Chris Newman, Masataka Ohta, George Rhoten, Karlsson, John Klensin, Alain LaBonte, Eric Mader, Ira McDonald,
Markus Scherer, Keld Jorn Simonsen, Thierry Sourbier, Otto Stolz, Tex Keith Moore, Chris Newman, Masataka Ohta, Randy Presuhn, George
Texin, Andrea Vine, Rhys Weatherley, Misha Wolf, Francois Yergeau and Rhoten, Markus Scherer, Keld Jorn Simonsen, Thierry Sourbier, Otto
many, many others. Stolz, Tex Texin, Andrea Vine, Rhys Weatherley, Misha Wolf, Francois
Yergeau and many, many others.
Very special thanks must go to Harald Tveit Alvestrand, who Very special thanks must go to Harald Tveit Alvestrand, who
originated RFCs 1766 and 3066, and without whom this document would originated RFCs 1766 and 3066, and without whom this document would
not have been possible. Special thanks must go to Michael Everson, not have been possible. Special thanks must go to Michael Everson,
who has served as language tag reviewer for almost the complete who has served as language tag reviewer for almost the complete
period since the publication of RFC 1766. Special thanks to Doug period since the publication of RFC 1766. Special thanks to Doug
Ewell, for his production of the first complete subtag registry, and Ewell, for his production of the first complete subtag registry, and
his work in producing a test parser for verifying language tags. his work in producing a test parser for verifying language tags.
Appendix B. Examples of Language Tags (Informative) Appendix B. Examples of Language Tags (Informative)
skipping to change at page 40, line 8 skipping to change at page 54, line 8
originated RFCs 1766 and 3066, and without whom this document would originated RFCs 1766 and 3066, and without whom this document would
not have been possible. Special thanks must go to Michael Everson, not have been possible. Special thanks must go to Michael Everson,
who has served as language tag reviewer for almost the complete who has served as language tag reviewer for almost the complete
period since the publication of RFC 1766. Special thanks to Doug period since the publication of RFC 1766. Special thanks to Doug
Ewell, for his production of the first complete subtag registry, and Ewell, for his production of the first complete subtag registry, and
his work in producing a test parser for verifying language tags. his work in producing a test parser for verifying language tags.
Appendix B. Examples of Language Tags (Informative) Appendix B. Examples of Language Tags (Informative)
Simple language subtag: Simple language subtag:
de (German) de (German)
fr (French) fr (French)
ja (Japanese) ja (Japanese)
i-enochian (example of a grandfathered tag) i-enochian (example of a grandfathered tag)
Language subtag plus Script subtag: Language subtag plus Script subtag:
zh-Hant (Traditional Chinese)
en-Latn (English written in Latin script) zh-Hant (Chinese written using the Traditional Chinese script)
sr-Cyrl (Serbian written with Cyrillic script)
zh-Hans (Chinese written using the Simplified Chinese script)
sr-Cyrl (Serbian written using the Cyrillic script)
sr-Latn (Serbian written using the Latin script)
Language-Script-Region: Language-Script-Region:
zh-Hans-CN (Simplified Chinese for the PRC)
sr-Latn-CS (Serbian, Latin script, Serbia and Montenegro) zh-Hans-CN (Chinese written using the Simlified script as used in
mainland China)
sr-Latn-CS (Serbian written using the Latin script as used in
Serbia and Montenegro)
Language-Variant:
en-boont (Boontling dialect of English)
en-scouse (Scouse dialect of English)
Language-Region-Variant:
en-GB-scouse (Scouse dialect of English as used in the UK)
Language-Script-Region-Variant: Language-Script-Region-Variant:
en-Latn-US-boont (Boontling dialect of English)
de-Latn-CH-1996 (German written in Latin script for Switzerland sl-Latn-IT-nedis (Nadiza dialect of Slovenian written using the
using the orthography of 1996) Latin script as used in Italy. Note that this tag is not
recommended because subtag 'sl' has a Suppress-Script value of
'Latn')
Language-Region: Language-Region:
de-DE (German for Germany) de-DE (German for Germany)
zh-SG (Chinese for Singapore)
cs-200 (Czech for Czechoslovakia) en-US (English as used in the United States)
sr-CS (Serbian for Serbia and Montenegro)
es-419 (Spanish for Latin America and Caribbean region using the es-419 (Spanish for Latin America and Caribbean region using the
UN region code) UN region code)
Other Mixtures: Private-use subtags:
en-boont (Boontling dialect of English)
private-use mechanism:
de-CH-x-phonebk de-CH-x-phonebk
az-Arab-x-AZE-derbend az-Arab-x-AZE-derbend
Extended language subtags (examples ONLY: extended languages must be Extended language subtags (examples ONLY: extended languages must be
defined by revision or update to this document): defined by revision or update to this document):
zh-min zh-min
zh-min-nan-Hant-CN zh-min-nan-Hant-CN
Private-use subtags: Private-use registry values:
x-whatever (private use using the singleton 'x') x-whatever (private use using the singleton 'x')
qaa-Qaaa-QM-x-southern (all private tags) qaa-Qaaa-QM-x-southern (all private tags)
de-Qaaa (German, with a private script) de-Qaaa (German, with a private script)
de-Latn-QM (German, Latin-script, private region)
de-Qaaa-DE (German, private script, for Germany) sr-Latn-QM (Serbian, Latin-script, private region)
sr-Qaaa-CS (Serbian, private script, for Serbia and Montenegro)
Tags that use extensions (examples ONLY: extensions must be defined Tags that use extensions (examples ONLY: extensions must be defined
by revision or update to this document or by RFC): by revision or update to this document or by RFC):
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)
Appendix C. Conversion of the RFC 3066 Language Tag Registry Appendix C. Example Registry
Upon publication of this document as a BCP, the existing IANA
language tag registry must be converted into the new subtag registry.
This section defines the process for performing this conversion.
The impact on the IANA maintainers of the registry of this conversion
will be a small increase in the frequency of new entries. The
initial set of records represents no impact on IANA, since the work
to create it will be performed externally.
When this document is published, an email will be sent by the
chair(s) of the LTRU working group to the LTRU and ietf-languages
mail lists advising of the impending conversion of the registry. In
that notice, the chair(s) will provide a URL whose referred content
is the proposed IANA Language Subtag Registry following conversion.
There will be a Last Call period of not less than four weeks for
comments and corrections to be discussed on the
ietf-languages@iana.org mail list. Changes as a result of comments
will not restart the Last Call period. At the end of the period, the
chair(s) will forward the URL to IANA, which will post the new
registry on-line.
Tags that are currently deprecated will be maintained as
grandfathered entries. The record for the grandfathered entry will
contain a note indicating that the entry is 'deprecated' and reason
for the deprecation. For example, the tag "art-lojban" is deprecated
and will be placed in the grandfathered section.
Tags that are not deprecated that consist entirely of subtags that
are valid under this document and which have the correct form and
format for tags defined by this document are superseded by this
document. Such tags are placed in the 'redundant' section of the
registry. For example, zh-Hant is now defined by this document.
Tags that contain subtags which are consistent with registration
under the guidelines in this document will have a new subtag
registration created for each eligible subtag. If all of the subtags
in the original tag are fully defined by the resulting registrations
or by this document, then the original tag is superseded by this
document. Such tags are placed in the 'redundant' section of the
registry. For example, en-boont will result in a new subtag "boont"
and the RFC 3066 registered tag 'en-boont' placed in the redundant
section of the registry.
Tags that contain one or more subtags that do not match the valid
registration pattern and which are not otherwise defined by this
document are marked as 'grandfathered' by this document.
There will be a reasonable period in which the community may comment
on the proposed list entries, which SHALL be no less than four weeks
in length. At the completion of this period, the chair(s) will
notify iana@iana.org and the ltru and ietf-languages mail lists that
the task is complete and forward the necessary materials to IANA for
publication.
Registrations that are in process under the rules defined in RFC 3066
MAY be completed under the former rules, at the discretion of the
language tag reviewer. Any new registrations submitted after the
request for conversion of the registry MUST be rejected.
All existing RFC 3066 language tag registrations will be maintained
in perpetuity.
Users of tags that are grandfathered should consider registering Example Registry
appropriate subtags in the IANA subtag registry (but are not required
to).
Where two subtags have the same meaning, the priority of which to File-Date: 2005-04-18
make canonical SHALL be the following: %%
o As of the date of acceptance of this document as a BCP, if a code Type: language
exists in the associated ISO standard and it is not deprecated or Subtag: aa
withdrawn as of that date, then it has priority. Description: Afar
o Otherwise, the earlier-registered tag in the associated ISO Added: 2004-07-06
standard has priority. %%
Type: language
Subtag: ab
Description: Abkhazian
Added: 2004-07-06
%%
Type: language
Subtag: ae
Description: Avestan
Added: 2004-07-06
%%
Type: language
Subtag: ar
Description: Arabic
Added: 2004-07-06
Suppress-Script: Arab
Comment: Arabic text is usually written in Arabic script
%%
Type: language
Subtag: qaa..qtz
Description: PRIVATE USE
Added: 2004-08-01
Comment: Use private use codes in preference
to the x- singleton for primary language
Comment: This is an example of two comments.
%%
Type: script
Subtag: Arab
Description: Arabic
Added: 2004-07-06
%%
Type: script
Subtag: Armn
Description: Armenian
Added: 2004-07-06
%%
Type: script
Subtag: Bali
Description: Balinese
Added: 2004-07-06
%%
Type: script
Subtag: Batk
Description: Batak
Added: 2004-07-06
%%
Type: region
Subtag: AA
Description: PRIVATE USE
Added: 2004-08-01
%%
Type: region
Subtag: AD
Description: Andorra
Added: 2004-07-06
%%
Type: region
Subtag: AE
Description: United Arab Emirates
Added: 2004-07-06
%%
Type: region
Subtag: AX
Description: &#xC5;land Islands
Added: 2004-07-06
Comments: The description shows a Unicode escape
for the letter A-ring.
%%
Type: region
Subtag: 001
Description: World
Added: 2004-07-06
%%
Type: region
Subtag: 002
Description: Africa
Added: 2004-07-06
%%
Type: region
Subtag: 003
Description: North America
Added: 2004-07-06
%%
Type: variant
Subtag: 1901
Description: Traditional German
orthography
Added: 2004-09-09
Recommended-Prefix: de
Comment: <shows continuation>
%%
Type: variant
Subtag: 1996
Description: German orthography of 1996
Added: 2004-09-09
Recommended-Prefix: de
%%
Type: variant
Subtag: boont
Description: Boontling
Added: 2003-02-14
Recommended-Prefix: en
%%
Type: variant
Subtag: gaulish
Description: Gaulish
Added: 2001-05-25
Recommended-Prefix: cel
%%
Type: grandfathered
Tag: art-lojban
Description: Lojban
Added: 2001-11-11
Canonical: jbo
Deprecated: 2003-09-02
%%
Type: grandfathered
Tag: en-GB-oed
Description: English, Oxford English Dictionary spelling
Added: 2003-07-09
%%
Type: grandfathered
Tag: i-ami
Description: 'Amis
Added: 1999-05-25
%%
Type: grandfathered
Tag: i-bnn
Description: Bunun
Added: 1999-05-25
%%
Type: redundant
Tag: az-Arab
Description: Azerbaijani in Arabic script
Added: 2003-05-30
%%
Type: redundant
Tag: az-Cyrl
Description: Azerbaijani in Cyrillic script
Added: 2003-05-30
%%
UN numeric codes assigned to 'macro-geographical (continental)' or Figure 7: Example of the Registry Format
sub-regions not associated with an assigned ISO 3166 alpha-2 code are
defined in the IANA registry and are valid for use in language tags.
These codes MUST be added to the initial version of the registry.
The UN numeric codes for 'economic groupings' or 'other groupings',
and the alphanumeric codes in Appendix X of the UN document MUST NOT
be added to the registry.
Intellectual Property Statement Intellectual Property Statement
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
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