Re: [Ltru] Re: Remove extlang from ABNF?

On Dec 12, 2007 8:22 AM, Addison Phillips <addison at yahoo-inc.com> wrote:

Felix Sasaki wrote:
>>
>> In RFC 4646, we defined some tags as well-formed. In RFC 4646bis, we
>> suddenly
>> say that some of these tags are not well-formed. We never would do
>> this for
>> valid tags, so I'm really not sure it is a good thing to do for
>> well-formed tags.
>>
> +1
>

I agree.... except....

This is exactly what we did in RFC 4646. We made a vast array of
"well-formed" but invalid tags illegal (by narrowing the ABNF). In
4646bis, one could say that we were doing the same thing--making a (much
smaller) array of tags (which were never valid) illegal. And we *have*
changed the ABNF in a manner that narrows it in 4646bis already. We have
narrowed the grandfathered production substantially.

I have no problem with XML Schema or others referencing the 4646 ANBF
instead of the 4646bis ABNF for well-formness checking. It won't
introduce anything particularly bad. And I am somewhat allergic to
changing the ABNF because I have personally felt like we should resist
tampering.

As an implementer, though, I really hate supporting extlang, now that it
does nothing. So I'd propose:

1. Remove extlang from the ABNF in 4646bis. That would make the language
production:

language = (2*3ALPHA) ; shortest ISO 639 code
/ 4ALPHA ; reserved for future use
/ 5*8ALPHA ; registered language subtag

2. In the section on conformance, permit 4646bis well-formedness to
reference either the current ABNF or an "obs-language" production that
looks like:

obs-language = (2*3ALPHA [ extlang ]) ; shortest ISO 639 code
/ 4ALPHA ; reserved for future use
/ 5*8ALPHA ; registered language subtag

extlang = *3("-" 3ALPHA) ; removed in this version

3. Add a note saying that no tags were ever valid under obs-language,
but that some processors may permit them. Also note that 3066
well-formedness differed substantially from 4646/4646bis well-formedness
and provide the 3066 production in that section for completeness.

Addison

--
Addison Phillips
Globalization Architect -- Yahoo! Inc.
Chair -- W3C Internationalization Core WG

Internationalization is an architecture.
It is not a feature.

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