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Re: New Last Call: 'Tags for Identifying Languages' to BCP

2004-12-21 10:57:25
 Date: 2004-12-18 23:37
 From: "Doug Ewell" <dewell(_at_)adelphia(_dot_)net>
 To: ietf-languages(_at_)alvestrand(_dot_)no
 
Bruce Lilly <blilly at erols dot com> wrote:

If you can write a reasonable "grandfathered" production in ABNF that
will allow this set of tags and no others, such that the ABNF can be
used without also referring to the prose, then I salute you.

If there really are only 24 items of less than 11 octets each,
a trivial solution is to simply list them (with the usual ABNF
syntax) as literal strings.  That should take no more than a
half-dozen lines.

Listing the 24 literal strings doesn't seem like a particularly elegant
solution.

Perhaps it doesn't meet your subjective criteria for elegance.
But it is a *reasonable* production that meets specific criteria,
and that is what you asked for.  A list of specific literal
strings is not unusual (e.g. RFC 3464 sect. 2.3.3, RFC 3798
sect. 3.2.6, RFC 2156 (summarized in Appendix E)).

Look, RFCs 1766 and 3066 both had ABNF that was insufficient to describe
the range of valid language tags, and AFAIK they were not greatly
criticized for this. [...] The same is true for RFC 3066bis.

A crucial difference is that RFC 3066 and 1766 required
registration before use, and community review before
registration.  If a tag were proposed that failed to meet
some criteria not adequately detailed in the ABNF, the
reviewer, the community, and the Area Director could
explain the issue *before* the darned thing went into use.
As that safety mechanism is being removed, it is more
important that the specification be clear and precise and
consistent.

RFC 2231, which you have mentioned often in this thread, has the
following as part of its ABNF:

-----begin pasted material-----
   charset := <registered character set name>

   language := <registered language tag [RFC-1766]>
-----end pasted material-----

If this type of syntax specification is good enough for RFC 2231, why
wouldn't it be good enough here?

RFC 2231 isn't BCP and doesn't obsolete BCP; it does not
remove any registration requirements.  While it obsoletes
another RFC (2184), it does not attempt to incorporate
content of the obsoleted RFC or artifacts of its use by a
vague reference.  Reference to (unaffected) external
specifications is fine; the draft uses RFC 2234 productions,
for example, and that is not a problem.

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