Network Working Group                                      D. Ewell, Ed.
Request for Comments: 5645                                    Consultant
Category: Informational                                   September 2009


                 Update to the Language Subtag Registry

Abstract

   This memo defines the procedure used to update the IANA Language
   Subtag Registry, in conjunction with the publication of RFC 5646, for
   use in forming tags for identifying languages.

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (c) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Updating the Registry  . . . . . . . . . . . . . . . . . . . .  2
     2.1.  Starting Point . . . . . . . . . . . . . . . . . . . . . .  2
     2.2.  New Language Subtags . . . . . . . . . . . . . . . . . . .  4
     2.3.  Modified Language Subtags  . . . . . . . . . . . . . . . .  5
     2.4.  New Region Subtags . . . . . . . . . . . . . . . . . . . .  6
     2.5.  Grandfathered and Redundant Tags . . . . . . . . . . . . .  6
     2.6.  Preferred-Value Changes  . . . . . . . . . . . . . . . . .  9
     2.7.  Additional Changes . . . . . . . . . . . . . . . . . . . .  9
   3.  Updated Registry Contents  . . . . . . . . . . . . . . . . . . 10
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 11
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . . 13

1.  Introduction

   [RFC4646] provides for a Language Subtag Registry and describes its
   format.  The initial contents of the registry and rules for
   determining them are specified in [RFC4645].

   [RFC5646] expands on [RFC4646] by adding support for approximately
   7,500 new primary and extended language subtags based on [ISO639-3]
   and [ISO639-5] alpha-3 code elements, and seven new region subtags
   based on [ISO3166-1] exceptionally reserved code elements.  This memo
   describes the process of updating the registry to include these
   additional subtags and to make secondary changes to the registry that
   result from adding the new subtags and from other decisions made by
   the Language Tag Registry Update (LTRU) Working Group.

   In writing this document, a complete replacement of the contents of
   the Language Subtag Registry was provided to the Internet Assigned
   Numbers Authority (IANA) to record the necessary updates.

   The format of the Language Subtag Registry as well as the definition
   and intended purpose of each of the fields are described in
   [RFC5646].

   The registry is expected to change over time, as new subtags are
   registered and existing subtags are modified or deprecated.  The
   process of updating the registry is described in Section 3 of
   [RFC5646].

   Many of the subtags defined in the Language Subtag Registry are based
   on code elements defined in [ISO639-1], [ISO639-2], [ISO639-3],
   [ISO639-5], [ISO3166-1], [ISO15924], and [UN_M.49].  The registry is
   not a mirror of the code lists defined by these standards and should
   not be used as one.

2.  Updating the Registry

   This section describes the process for determining the updated
   contents of the Language Subtag Registry.

2.1.  Starting Point

   The version of the Language Subtag Registry that was current at the
   time of IESG approval of this memo served as the starting point for
   this update.  This version was created according to the process
   described in [RFC4645] and maintained according to the process
   described in [RFC4646].

   The source data for [ISO639-3] used for this update consisted of
   three files, available from the official site of the ISO 639-3
   Registration Authority.  (Note that this file is updated from time to
   time.  The version used in the preparation of this memo was the one
   in place on February 24, 2009.)

   o  [iso-639-3_20090210] is a list of all language code elements in
      [ISO639-3], including the alpha-3 code element and reference name
      for each code element.  For example, the entry for the Dari
      language contained the code element 'prs' and the name "Dari"
      (among other information).

   o  [iso-639-3_Name_Index_20090210] is a list containing all names
      associated with each language according to [ISO639-3], including
      both inverted and non-inverted forms where appropriate.  An
      "inverted" name is one that is altered from the usual English-
      language order by moving adjectival qualifiers to the end, after
      the main language name and separated by a comma.  A code element
      may have more than one entry in this file; the reference name and
      its inverted form are usually, but not always, given in the first
      entry.  For example, this file contained an entry for the code
      element 'prs' with the name "Dari" (twice) and another entry with
      the names "Eastern Farsi" and "Farsi, Eastern".

   o  [iso-639-3-macrolanguages_20090120] is a list of all alpha-3 code
      elements for languages that are encompassed by a macrolanguage in
      [ISO639-3], together with the alpha-3 code element for the
      macrolanguage.  For example, a line containing the code elements
      'fas' and 'prs' indicated that the macrolanguage "Persian"
      encompasses the individual language "Dari".  (Note that these
      alpha-3 code elements may not have corresponded directly to
      subtags in the registry, which uses 2-letter subtags derived from
      [ISO639-1] when possible.)

   The source data for [ISO639-5] used for this update consisted of one
   file, available from the official site of the ISO 639-5 Registration
   Authority.  (Note that this file is updated from time to time.  The
   version used in the preparation of this memo was the one in place on
   February 24, 2009.)

   o  [iso639-5.tab.txt] is a list of all language code elements in
      [ISO639-5], including the alpha-3 code elements and English name
      for each code element.  For example, this file includes an entry
      containing the code element 'ira' and the name "Iranian languages"
      (among other information).

   Language code elements that were already retired in all of the source
   standards prior to IESG approval of this memo were not listed in
   these files and, consequently, were not considered in this update.

   The values of the File-Date field, the Added date for each new subtag
   record, and the Deprecated date for each existing grandfathered or
   redundant tag deprecated by this update were set to a date as near as
   practical to the date this memo was approved for publication by IESG.

2.2.  New Language Subtags

   For each language in [ISO639-3] that was not already represented by a
   language subtag in the Language Subtag Registry, a new language
   subtag was added to the registry, using the [ISO639-3] code element
   as the value for the Subtag field and using each of the non-inverted
   [ISO639-3] names as a separate Description field.  The [ISO639-3]
   reference name is represented by the first Description field.

   If the language was encompassed by one of the [ISO639-3]
   macrolanguages 'ar' (Arabic), 'kok' (Konkani), 'ms' (Malay), 'sw'
   (Swahili), 'uz' (Uzbek), or 'zh' (Chinese), as determined by
   [iso-639-3-macrolanguages_20090120], an extended language subtag was
   also added, with the primary language subtag of the macrolanguage as
   the value for the Prefix field.  These macrolanguage subtags were
   already present in the Language Subtag Registry and were chosen
   because they were determined by the LTRU Working Group to have been
   used to represent a single dominant language as well as the
   macrolanguage as a whole, making the extended language mechanism
   suitable for languages encompassed by the macrolanguage.

   If the name of the language included the word "Sign", an extended
   language subtag was added, with the string "sgn" as the value for the
   Prefix field.  This is a special case that treats the existing
   primary language subtag for "Sign languages" as if it were a
   macrolanguage encompassing all sign languages.

   All extended language subtags were added with a Preferred-Value equal
   to the corresponding primary language subtag.

   If the language was encompassed by a macrolanguage, as determined by
   [iso-639-3-macrolanguages_20090120], a Macrolanguage field was added
   for the encompassed language, with a value equal to the subtag of the
   macrolanguage.  (Note that 'sgn' is defined as a "collection code" by
   [ISO639-3] and hence is not included in that standard; therefore, no
   Macrolanguage field was added for sign language subtags.)

   If the language was assigned a "Scope" value of 'M' (Macrolanguage)
   in [iso-639-3_20090210], a Scope value of "macrolanguage" was added

   for the language.  Otherwise, if the language was assigned a "Scope"
   value of 'S' (Special), a Scope value of "special" was added.  Most
   languages in [ISO639-3] have scope 'I' (Individual) and thus were not
   assigned a Scope value in the registry.

   For each language in [iso639-5.tab.txt] that was not already
   represented by a language subtag in the Language Subtag Registry, a
   new language subtag was added to the registry, using the [ISO639-5]
   code element as the value for the Subtag field and using the "English
   name" field as the Description field.  Each of these languages was
   assigned a Scope value of "collection" in the registry.

   All subtags were added to the registry maintaining alphabetical order
   within each type of subtag: all 2-letter "language" subtags first,
   then all 3-letter "language" subtags, and finally all "extlang"
   subtags.  Some existing records were moved to ensure this order.

2.3.  Modified Language Subtags

   For each language in [ISO639-3] that was already represented by a
   language subtag in the Language Subtag Registry, Description fields
   were added as necessary to reflect all non-inverted names listed for
   that language in [iso-639-3_Name_Index_20090210].  Any existing
   Description fields that reflected inverted names or that represented
   a strict subset of the information provided by the [ISO639-3] name
   were deleted.  An example of the latter was the name "Ainu" for the
   subtag 'ain', which provided less information than the [ISO639-3]
   name "Ainu (Japan)".

   The order of Description fields was adjusted to ensure that the
   reference name from [ISO639-3] was listed first, followed by other
   names from [ISO639-3] in the order presented by that standard,
   followed by any other names already existing in the registry.  In
   some cases, this resulted in a reordering of Description fields for
   existing entries, even when no new values were added.

   For each language that was encompassed by a macrolanguage in
   [ISO639-3], a Macrolanguage field was added, with a value equal to
   the subtag of the macrolanguage.

   For each language in [iso639-5.tab.txt] that was already represented
   in the Language Subtag Registry, the Description field was adjusted
   as necessary to match the "English name" field in [iso639-5.tab.txt].
   Names in inverted form were rearranged to remove the inversion.  Each
   of these languages was assigned a Scope value of "collection".
   Existing language subtags whose code elements were assigned prior to
   the publication of [ISO639-3] or [ISO639-5] and that were identified
   by the [ISO639-3] Registration Authority as representing collections

   were also assigned a Scope value of "collection", even though they
   are not listed as such in [iso639-5.tab.txt].

   Note in particular that the change from [ISO639-2] names such as
   "Afro-Asiatic (Other)" to [ISO639-5] names such as "Afro-Asiatic
   languages" implies a broadening of scope for some of these subtags,
   designated "remainder groups" in [ISO639-5].  While
   [iso639-5.tab.txt] includes a field indicating which code elements
   are designated as "groups" or "remainder groups" in [ISO639-2],
   [RFC5646] does not make this distinction, and consequently this field
   was not used in updating the Language Subtag Registry.

   A Scope value of "private-use" was added for the unique record with
   Subtag value 'qaa..qtz'.  This record has a Description of "Private
   use" (changed from "PRIVATE USE") and corresponds to a range of code
   elements that is reserved for private use in [ISO639-2].  The
   Description fields for script and region private-use subtags were
   also capitalized as "Private use".

2.4.  New Region Subtags

   [RFC5646] expands the scope of region subtags by adding subtags based
   on code elements defined as "exceptionally reserved" in [ISO3166-1].
   These code elements are reserved by the ISO 3166 Maintenance Agency
   "at the request of national ISO member bodies, governments and
   international organizations".  At the time of IESG approval of this
   memo, ISO 3166/MA had defined nine exceptionally reserved code
   elements, all of which were added to the Language Subtag Registry
   except for the following:

   o  'FX' (Metropolitan France) was already present in the Language
      Subtag Registry because it was an assigned [ISO3166-1] code
      element from 1993 to 1997, but was deprecated with a Preferred-
      Value of "FR".

   o  'UK' (United Kingdom) was not added because it is associated with
      the same UN M.49 code (826) as the existing region subtag 'GB'.
      [RFC5646], Section 3.4, item 15 (D) states that a new region
      subtag is not added to the Language Subtag Registry if it carries
      the same meaning as an existing region subtag.

2.5.  Grandfathered and Redundant Tags

   As stated in [RFC5646], "grandfathered" and "redundant" tags are
   complete tags in the Language Subtag Registry that were registered
   under [RFC1766] or [RFC3066] and remain valid.  Grandfathered tags
   cannot be generated from a valid combination of subtags, while
   redundant tags can be.

   Under certain conditions, registration of a subtag under [RFC5646]
   may cause a grandfathered tag to be reclassified as redundant.  It
   may also enable the creation of a generative tag with the same
   meaning as a grandfathered or redundant tag; in that case, the
   grandfathered or redundant tag is marked as Deprecated, and the
   generative tag (including the new subtag) becomes its Preferred-
   Value.

   As a result of adding the new subtags in this update, each of the
   following grandfathered tags became composable, were reclassified as
   redundant, and were deprecated with the indicated generative tag
   serving as the Preferred-Value:

      zh-cmn (Preferred-Value: cmn)

      zh-cmn-Hans (Preferred-Value: cmn-Hans)

      zh-cmn-Hant (Preferred-Value: cmn-Hant)

      zh-gan (Preferred-Value: gan)

      zh-wuu (Preferred-Value: wuu)

      zh-yue (Preferred-Value: yue)

   The following grandfathered tags were deprecated, with the indicated
   generative tag serving as the Preferred-Value:

      i-ami (Preferred-Value: ami)

      i-bnn (Preferred-Value: bnn)

      i-pwn (Preferred-Value: pwn)

      i-tao (Preferred-Value: tao)

      i-tay (Preferred-Value: tay)

      i-tsu (Preferred-Value: tsu)

      zh-hakka (Preferred-Value: hak)

      zh-min (no Preferred-Value; see below)

      zh-min-nan (Preferred-Value: nan)

      zh-xiang (Preferred-Value: hns)

   The tag "zh-min", originally registered under [RFC1766], is a special
   case: it represents a small class of Chinese languages, but is not a
   true macrolanguage.  The string "min" could not ever be used to tag
   these languages since the [ISO639-3] code element 'min' is assigned
   to an individual language (Minangkabau) that is not related to
   Chinese ('zh').  Because it is not believed to represent a useful
   linguistic entity for tagging purposes, it was deprecated without a
   Preferred-Value.

   The following grandfathered and redundant sign language tags were
   deprecated, with the indicated generative tag serving as the
   Preferred-Value:

      sgn-BE-FR (Preferred-Value: sfb)

      sgn-BE-NL (Preferred-Value: vgt)

      sgn-BR (Preferred-Value: bzs)

      sgn-CH-DE (Preferred-Value: sgg)

      sgn-CO (Preferred-Value: csn)

      sgn-DE (Preferred-Value: gsg)

      sgn-DK (Preferred-Value: dsl)

      sgn-ES (Preferred-Value: ssp)

      sgn-FR (Preferred-Value: fsl)

      sgn-GB (Preferred-Value: bfi)

      sgn-GR (Preferred-Value: gss)

      sgn-IE (Preferred-Value: isg)

      sgn-IT (Preferred-Value: ise)

      sgn-JP (Preferred-Value: jsl)

      sgn-MX (Preferred-Value: mfs)

      sgn-NI (Preferred-Value: ncs)

      sgn-NL (Preferred-Value: dse)

      sgn-NO (Preferred-Value: nsl)

      sgn-PT (Preferred-Value: psr)

      sgn-SE (Preferred-Value: swl)

      sgn-US (Preferred-Value: ase)

      sgn-ZA (Preferred-Value: sfs)

   No change was made to the Description field(s) for any of the
   grandfathered or redundant tags.  For example, the redundant tag
   "sgn-US" continues to carry the Description "American Sign Language".
   The sign language tags registered prior to [RFC4646] remain an
   exception to the general principle that the meaning of a non-
   grandfathered tag can be derived from its component subtags.

   In previous versions of the registry, grandfathered tags that had
   been deprecated as a result of adding an ISO 639-based language
   subtag included a Comments field, with a value of the form "replaced
   by ISO code xxx", where 'xxx' represented the new language subtag.
   These comments duplicated the information contained within the
   Preferred-Value field and were deleted as part of this update.  No
   changes were made to other Comments fields.

2.6.  Preferred-Value Changes

   [RFC5646], Section 3.1.7 provides for the value of Preferred-Value
   fields to be updated as necessary to reflect changes in one of the
   source standards.  Accordingly, the Preferred-Value fields for the
   following deprecated tags were changed:

      i-hak (changed from zh-hakka to hak)

      zh-guoyu (changed from zh-cmn to cmn)

   This makes it unnecessary for consumers of the Language Subtag
   Registry to follow a "chain" of Preferred-Values in order to arrive
   at a non-deprecated subtag.

2.7.  Additional Changes

   For consistency with the handling of alternative names in language
   subtags, Description fields for script subtags taken from [ISO15924]
   that represent alternative names were converted to multiple
   Description fields.  For example, the Description "Han (Hanzi, Kanji,
   Hanja)" was converted to four separate Description fields.  Some
   Description fields for script subtags contained parenthetical
   material that was explanatory, rather than identifying alternative
   names; these fields were not altered.

   This situation does not apply to region subtags taken from
   [ISO3166-1] and [UN_M.49] because those standards do not provide
   freely available alternative names for code elements.

   Description fields in inverted form for script and region subtags
   were rearranged to remove the inversion, for consistency with the
   handling of language subtags in Sections 2.2 and 2.3.  For example,
   the Description field "Korea, Republic of" was changed to "Republic
   of Korea".

   The capitalization of the Subtag fields for certain grandfathered and
   redundant tags (sgn-BE-fr, sgn-BE-nl, sgn-CH-de, and yi-latn) was
   modified to conform with the capitalization conventions described in
   [RFC5646], Section 2.1.1.  This has no effect on the validity or
   meaning of these tags.

   The Description field for subtag 'sgn' was capitalized as "Sign
   languages" to match the capitalization used for other languages in
   [ISO639-5], even though this capitalization does not exactly match
   that used for code element 'sgn' in any of the ISO 639 parts.

   The Deprecated field for the region subtag TP was modified from 2002-
   11-15 to 2002-05-20, to correct a clerical error.  The corrected date
   reflects the actual date the code element TP was withdrawn in
   [ISO3166-1].

   The order of fields within records in the registry was adjusted as
   necessary to match the order in which these fields are described in
   [RFC5646], Section 3.1.2.  This ordering is not required by [RFC5646]
   and may not necessarily be reflected in future additions or
   modifications to the registry.

3.  Updated Registry Contents

   IANA has updated the Language Subtag Registry according to the
   provided replacement contents.  The replacement content was listed in
   the working draft of this document, but was deleted prior to
   publication as an RFC to avoid potential confusion with the registry
   itself.  The Language Subtag Registry is available from the IANA
   website, <http://www.iana.org>.

4.  Security Considerations

   For security considerations relevant to the Language Subtag Registry
   and the use of language tags, see [RFC5646].

5.  IANA Considerations

   IANA has updated the Language Subtag Registry, which can be found via
   <http://www.iana.org>.  For details on the procedures for the format
   and ongoing maintenance of this registry, see RFC 5646.

6.  References

6.1.  Normative References

   [ISO639-3]  International Organization for Standardization, "ISO 639-
               3:2007.  Codes for the representation of names of
               languages - Part 3: Alpha-3 code for comprehensive
               coverage of languages", February 2007.

   [ISO639-5]  International Organization for Standardization, "ISO 639-
               5:2008.  Codes for the representation of names of
               languages -- Part 5: Alpha-3 code for language families
               and groups", May 2008.

   [RFC5646]   Phillips, A., Ed. and M. Davis, Ed., "Tags for
               Identifying Languages", RFC 5646, September 2009.

   [iso-639-3-macrolanguages_20090120]
               International Organization for Standardization, "ISO
               639-3 Macrolanguage Mappings", January 2009, <http://
               www.sil.org/iso639-3/
               iso-639-3-macrolanguages_20090120.tab>.

   [iso-639-3_20090210]
               International Organization for Standardization, "ISO
               639-3 Code Set", February 2009,
               <http://www.sil.org/iso639-3/iso-639-3_20090210.tab>.

   [iso-639-3_Name_Index_20090210]
               International Organization for Standardization, "ISO
               639-3 Language Names Index", February 2009,
               <http://www.sil.org/
               iso639-3/iso-639-3_Name_Index_20090210.tab>.

   [iso639-5.tab.txt]
               International Organization for Standardization, "ISO
               639-5 code list, Tab-delimited text", February 2009,
               <http://www.loc.gov/standards/iso639-5/iso639-5.tab.txt>.

6.2.  Informative References

   [ISO15924]  International Organization for Standardization, "ISO
               15924:2004.  Information and documentation -- Codes for
               the representation of names of scripts", January 2004.

   [ISO3166-1] International Organization for Standardization, "ISO
               3166- 1:2006.  Codes for the representation of names of
               countries and their subdivisions -- Part 1: Country
               codes", November 2006.

   [ISO639-1]  International Organization for Standardization, "ISO 639-
               1:2002.  Codes for the representation of names of
               languages -- Part 1: Alpha-2 code", July 2002.

   [ISO639-2]  International Organization for Standardization, "ISO 639-
               2:1998.  Codes for the representation of names of
               languages -- Part 2: Alpha-3 code", October 1998.

   [RFC1766]   Alvestrand, H., "Tags for the Identification of
               Languages", RFC 1766, March 1995.

   [RFC3066]   Alvestrand, H., "Tags for the Identification of
               Languages", RFC 3066, January 2001.

   [RFC4645]   Ewell, D., "Initial Language Subtag Registry", RFC 4645,
               September 2006.

   [RFC4646]   Phillips, A. and M. Davis, "Tags for Identifying
               Languages", BCP 47, RFC 4646, September 2006.

   [UN_M.49]   Statistics Division, United Nations, "Standard Country or
               Area Codes for Statistical Use", Revision 4 (United
               Nations publication, Sales No. 98.XVII.9, June 1999.

Appendix A.  Acknowledgements

   This memo is a collaborative work of the Language Tag Registry Update
   (LTRU) Working Group.  All of its members have made significant
   contributions to this memo and to its predecessor, [RFC4645].

   Specific contributions to this memo were made by Stephane Bortzmeyer,
   John Cowan, Mark Davis, Martin Duerst, Frank Ellermann, Debbie
   Garside, Kent Karlsson, Gerard Lang, Addison Phillips, Randy Presuhn,
   and CE Whitehead.

Author's Address

   Doug Ewell (editor)
   Consultant

   EMail: doug@ewellic.org
   URI:   http://www.ewellic.org