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

[Ken Lunde]

John,

From Unicode's point of view, it makes sense to have Hiragana and Katakana as separate scripts. From a functional or typographic point of view, they are treated the same, which explains why a single script tag is used in OpenType.

So, to answer your question, I think it is the former.

I am simply trying to simplify the table without removing information, and my suggestion does precisely this.

Best...

-- Ken

> On Mar 31, 2016, at 4:44 PM, John Hudson <john at tiro.ca> wrote:
> 
> 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
>