Re: RDF-ISSUE-64 (langtag-rfc): RFC 3066 or RFC 5646 for language tags? [RDF General]

On May 30, 2011, at 1:29 PM, Richard Cyganiak wrote:

> On 30 May 2011, at 17:22, Pat Hayes wrote:
>>> RDF-ISSUE-64 (langtag-rfc): RFC 3066 or RFC 5646 for language tags? [RDF General]
>>> 
>>> http://www.w3.org/2011/rdf-wg/track/issues/64
>>> 
>>> RDF Concepts defines language tags with reference to RFC 3066.
>>> 
>>> RFC 3066 is obsoleted by RFC 5646.
>>> 
>>> Should language-tagged literals in RDF 1.1 still be defined in terms of the (simple) RFC 3066, or in terms of the (much more hairy) RFC 5646?
>> 
>> Seems like a no-brainer to me. We should refer to the latest spec, not to any obsoleted spec. Users who seriously care about language tagging will presumably require the latest specs. Users who don't will not give a toss one way or the other. Making our lives easier by avoiding hairiness is not an option. 
> 
> I have to admit that I only skimmed both specs, so I might be wrong here.
> 
> RFC 3066 had a quite simple generic grammar for language tags. Groups of letters/numbers separated by dashes. This can be checked with one simple regex.
> 
> RFC 5646 explicitly enumerates most of the “words” that are allowed in language tags. The grammar is several pages.
> 
> I read this as saying that "kx-kx-kx" is a valid RFC 3066 language tag, but not a valid RFC 5646 language tag. So "foo"@kx-kx-kx is a valid object in RDF 2004, but not in RDF 1.1?

Ah, I see what you are getting at. No, I don't think we should go this route. We can simply say that an RDF literal tag is any string of characters (as far as RDF is concerned, that is.) So "foo"@kx-kx-kx is a legal RDF literal, as indeed is "foo"@the-quality-of-mercy-is-not-strained. Nevertheless, we can refer to RFC 5646 for the meaning of the term 'language tag'. 

> Will implementing a conformant RDF 1.1 system require an implementation of the full RFC 5646 grammar?

No. I don't think RDF parsers should be required to MUST check legality of language tags. They MAY do so, of course, if that is found useful, and they MAY emit error messages when they find bad ones, but they aren't obliged to do these checks. 

Pat

> This would be a significant cost and I'm not sure it would be good value for money.
> 
> Best,
> Richard

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Received on Monday, 30 May 2011 18:38:02 UTC