script tags update (Re: [mpeg-OTspec] Digest Number 549)

[John Hudson]

On 31/03/16 14:29, 'Adam Twardoch (List)' list.adam at twardoch.com 
[mpeg-OTspec] wrote:

> In Unicode, Hiragana and Katakana are classified as separate scripts, 
> in OpenType, they share one script tag. There is nothing wrong with 
> that by itself — the OpenType script tags are primarily a mechanism to 
> activate a certain "script-specific processing sub-engine" within the 
> OpenType Layout engine, and both kana variants can be processed with 
> the same sub-engine because their behavioral logic is practically the 
> same. 

Out of idle interest:

Is the implication of this that Katakana and Hiragana runs identified 
and separated by script itemisation — based on Unicode script property — 
are passed to a single layout engine that processes glyphs for both 
using features and lookups mapped in the <kana> OTL script tag?

Or is the implication that Katakana and Hiragana, if adjacent, are 
rolled into a single 'kana' run before being passed to the layout engine?


JH

-- 

John Hudson
Tiro Typeworks Ltd    www.tiro.com
Salish Sea, BC        tiro at tiro.com

Getting Spiekermann to not like Helvetica is like training
a cat to stay out of water. But I'm impressed that people
know who to ask when they want to ask someone to not like
Helvetica. That's progress. -- David Berlow