Use of "CS" for 'Serbia and Montenegro'

[Bruce Lilly]

>  Date: 2005-01-10 00:53
>  From: "Peter Constable" <petercon at microsoft.com>

> Per RFC 3066, it is not required that "sr-CS" be registered before that
> language tag can be used.
> 
> Because of ambiguity of the semantics, it may be necessary to ensure
> inter-operability to register "sr-CS" to eliminate that clarify the
> intended semantics of that tag.
[...]
> On the contrary, registration could serve to eliminate the ambiguity. 
> 
> And just to make sure we don't end up speaking past one another due to
> unstated assumptions, my assumption is that ambiguity in the semantics
> of this metadata element is a bad thing.

No argument on that point.  My assumption is that RFC 3066 language-tag
parsers conform to RFC 3066 rules, viz.:

   The following rules apply to the second subtag:

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

Note that it says "codes from [ISO 3166]", so it doesn't make one
whit of difference if such a tag is registered in an IANA registry;
every 2-letter second subtag is always interpreted per ISO 3166, so
to the extent that 3166 can be considered to be ambiguous, such
ambiguity is unaffected by registry of any tag with a 2-letter
second subtag.