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[Bug 14709] lang tag validation is insufficiently specified

From: <bugzilla@jessica.w3.org>
Date: Mon, 07 Nov 2011 17:30:22 +0000
To: public-html-bugzilla@w3.org
Message-Id: <E1RNT1a-0003IT-Bd@jessica.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=14709

Glenn Adams <glenn@skynav.com> changed:

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--- Comment #4 from Glenn Adams <glenn@skynav.com> 2011-11-07 17:30:20 UTC ---
(In reply to comment #1)
> Another way to look at this problem is "should ISO 639-3 (three-letter) codes
> be allowed when the BCP47 tag for a given language is the two-letter ISO 639-1
> code?"

Since BCP47 says:

2.2.8.  Grandfathered and Redundant Registrations

   Prior to RFC 4646, whole language tags were registered according to
   the rules in RFC 1766 and/or RFC 3066.  All of these registered tags
   remain valid as language tags.

and since RFC1766 allows both 2 and 3 letter primary language tags but doesn't
require shortest use, the restriction you propose above would effectively
subset BCP47, which is undesirable, and could reduce interoperability.

I would suggest that HTML5 say nothing about validity or meaning of language
tags other than what is currently said, or, if desired, refer to:

BCP47 4.2 Meaning of the Language Tag
BCP47 4.5 Canonicalization of Language Tags

If the UA implementation uses some lower-level service, such as OpenType
services, it should be the responsibility of the UA to convert and/or
canonicalize BCP47 language tags into a form suitable for the lower-level
service.

For example, OpenType defines its own language system tag (LangSysTag) registry
[1], which is distinct from (though based in part on) ISO639, and thus distinct
from BCP47 and HTML5's lang/xml:lang value spaces.

[1] http://www.microsoft.com/typography/otspec/languagetags.htm

HTML5 should not attempt to reflect dependencies at such low-level service APIs
back into the definition of lang/xml:lang; rather, the  UA should be
responsible for mapping the latter to the former.

So I would argue for no change to the current HTML5 language in this context.

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Received on Monday, 7 November 2011 17:30:33 GMT

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