Re: font features in CSS

Martin J. Dürst wrote:

> HTML lang and XML xml:lang use BCP 47 (http://tools.ietf.org/html/bcp47, 
> formerly RFC 1766/3066/4646) tags, not ISO 639 directly....

It should be noted that 'language system' in the context of OpenType 
Layout is a misnomer, because that these tags actually represent are 
typographic conventions -- most obviously, culturally preferred glyph 
shapes --, which are very often identified with language use but not 
always or necessarily. This is why OTL language system tagging does not 
use one of the two or three letter language code standards: the 
expectation was always that some sets of typographic conventions would 
not be mappable to languages or, as Adam notes, to might map to multiple 
languages, or, indeed, that some users of a particular language would 
want to employ 'language system' conventions of another language.

I agree with Adam that it is desirable to have a mechanism to directly 
address OTL language system tags for display independent of language 
tagging of content.

JH