[mpeg-OTspec] Armenian East-West Distinctions

[John Hudson]

On 10/07/13 10:01 AM, Andrew Glass (WINDOWS) wrote:

> There are a couple of options here: make a new language tag or make a
> new script tag. In principle, the language is the same, so it is not
> appropriate to make a new language tag – I believe that ISO 639-3
> registration authority would reject the request. The differences you
> refer to are in the orthography, and so a script difference is
> appropriate. There is precedent for script variants to be given distinct
> script codes within ISO 15924. See for example Syriac, Han, and Latin:

Yes, this makes sense in the context of ISO 639-3 and ISO 15924, but not 
in the context of OpenType language system tags, I think. The convention 
there has always been to make orthographic distinctions at the language 
system tag level, and to reserve the script tag to reference Unicode 
scripts. This is what enables OTL engines to make decisions about script 
tag based on character codes in the text, and fonts to provide 
orthographic variation based on language system tagging. This is also, 
of course, why mapping OTL language system tags to ISO 639 document 
language tags will always remain hit-and-miss: they record different 
kinds of information (which is why, sensibly, CSS3 provides for OTL 
language system tagging independent of text language tagging).

In the case of East vs West Armenian, it does look like ISO conventions 
would favour a script tag distinction. But that doesn't get us any 
closer to being able to affect orthographic distinctions within OpenType 
glyph processing, since regardless of script tag the Unicode script is 
the same, and OTL language system tag is the normal place to capture 
orthographic distinctions within a script.

JH


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