Re: [css3-text] script categories, 'bicameral', 'discrete', Unicode links and more

Thanks, John, for giving some more detail here. Altogether, it confirms 
my unease with simple "script level" classifications in a document that 
necessarily has to be brief.

If generic observations about script behavior are seen as useful, then 
they should really be proposed to be added to the Unicode Script 


On 4/15/2011 12:38 PM, John Hudson wrote:
> Asmus wrote:
>> In English you may find narrow columns that are typeset with 
>> letterspacing to make them justified. If you do the same in German, 
>> many readers will mistake this for an attempt at  e m p h a s i s. 
>> (It used to be more common, especially so during the age of Fraktur, 
>> but it's widespread enough that some people use it manually, like I 
>> did here, in internet postings).
>> Whether letter-spacing is "allowed" for justification depends thus 
>> not only on the script, but on (local) conventions. In the example I 
>> gave, letter-spacing is allowed for emphasis, but not for 
>> justification (the latter, if you attempted it, would look like a 
>> ransom note to readers who are used to interpret letterspacing as 
>> emphasis).
> ...
>> In typesetting German in Fraktur there are a number of required 
>> ligatures. These are not broken apart when letterspacing is applied 
>> (for emphasis).
> Yes, there is a hierarchy of typographic behaviours that is 
> expressible as either
>     Script -> Language -> Style
> or as
>     Script -> Style -> Language
> which is to say that sometimes the language (perhaps better thought of 
> as local conventional) behaviour is a variation of the typical 
> script-level behaviour and sometimes it is a variation within a 
> particular style that is itself a variation of the script-level 
> behaviour. In functional terms, sometimes you want to define language 
> level behaviour in contrast to script level behaviour, while at other 
> times one wants to insert the style behaviour between the script and 
> the language levels.
> [At the font level, OpenType enforces a script-language-lookup 
> hierarchy, which means that style behaviour, insofar as it is possible 
> to define this with regard to GSUB and GPOS layout, is implemented at 
> the lookup level. This works, but isn't always as efficient as it 
> would be if there were the option to define a style level between 
> script and language. It is possible, within this system, to inhibit 
> letter spacing by using the <curs> Cursive Attachment GPOS lookup 
> type, which locks glyphs together in particular x,y relationships; 
> however, the majority of Latin script cursive style fonts do not 
> implement this because they do not employ any y-direction position 
> adjustments, and hence do not strictly need <curs> attachment for most 
> layout needs.]
> JH

Received on Friday, 15 April 2011 20:54:30 UTC