No subject

A.  Codes assigned by ISO 639-1 that do not conflict
> with
    existing two-letter primary language subtags and that have
    no
> corresponding three-letter primary defined in the
    registry are entered
> into the IANA registry as new records
    of type 'language'.  Note that
> languages given an ISO 639-1
    code cannot be given extended language
> subtags, even if
    encompassed by a macrolanguage.

And from RFC 5645,
> Section 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.

There is no
> similar wording in Section 2.3 ("Modified Language 
Subtags"), by design.  In
> the (many times repeated) production of the 
RFC 5645 Registry, only newly
> created language subtags were considered 
as candidates for extlangs.
> Existing language subtags were not examined 
as part of this process.

--
Doug
> Ewell  |  Thornton, Colorado, USA  |  http://www.ewellic.org
RFC 5645, 4645,
> UTN #14  |  ietf-languages @ http://is.gd/2kf0s
> =A1=A9

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