Re: How to write Armenian ligatures?

On 11/24/2007 2:31 PM, John H. Jenkins wrote:
> I can't speak for other platforms, but on Mac OS X, the normal 
> behavior for Latin text is that plain text uses whatever ligatures the 
> font has on by default.
>
> I, at least, would argue that ligation controls don't (as a rule) 
> belong in plain text, since ligation is intimately bound with the 
> typographic needs of a specific font.
That sounds like the unreconstructed and simplistic view of the 
character glyph model with which Unicode started out, and which caused 
(and causes) all kinds of trouble.

To summarize some of the key issues that should by now be recognized as 
requirements for the full character glyph model:

1) Some scripts have required ligatures
2) Some font styles have required ligatures ('ch' in Fraktur, but not in 
most other Latin styles)
3) Some languages have *prohibited* ligatures
4) Some scripts require additional levels of choice (e.g. up to four in 
Indic)
5) Some users have special needs for additional control over ligatures 
(extreme design)

The full character glyph model needs to allow for all of these - while 
minimizing impact on what gets encoded.

In that sense, the OpenType technology has gotten a lot of things right 
by providing the three levels of ligatures that John Hudson summarized 
here (required, standard, and discretionary).

However, feature 3and 4 will not work without giving the user a way to 
(locally) override the global settings. As the requirement for 
prohibition of ligatures often comes from orthography (or if you want, 
from the intersection of orthography and typography) it is appropriate 
to use coded characters. (In the kinds of cases that were discussed on 
this list at length, allowing a ligature changes the possible readings 
of the word in question - that's no longer typography pure, that's 
orthography).

Luckily, it seems, that the ZWNJ is the only character that's required 
for language-specific requirements - at least I don't know an example to 
the contrary. The problem is, when should the user supply them. If 
ligatures are disabled by default, then the ZWNJ is not needed (the 
option of not using any ligatures is permissible in many type styles 
(though not Fraktur)).

In some sense then, if non-required, but non-fancy, ligatures were 
always enabled, users would (need to) supply the ZWNJ by default, and 
text would be correctly coded. But leaving ligatures enabled by default 
makes the use of plain text controls, in this case, ZWNJ required. 
Otherwise, you get what are essentially misspelled words (or 
mis-typeset, if you want) in these languages.

You can't have one without the other, that's why I called your statement 
a "simplistic" view of the character glyph model.

I think it's worth repeating that there is another dimension where it is 
in fact up to the font to make decision on ligatures.

A Fraktur font would need to supply all the ligatures that are required 
in Fraktur (e.g. also the 'ch' ligature) and mark them as "required", 
because in that typographical style they are required, even though in 
other Latin styles they may not be. A monospaced font would not normally 
support any ligatures as either required or default (as John Hudson 
pointed out a couple of posts ago), because doing so would violate the 
general expectation that users of monospaced fonts have of getting one 
display position for each 'character'.

For Indic scripts, the model has come together over the last decade, and 
it looks like all the distinctions can be represented on the character 
code level.

Finally for designers, you'll always need additional controls, which 
specialized applications and fonts will supply.

So, it looks like the character glyph model is finally getting broad 
enough to meet the real requirements, but only if you allow both turning 
on some ligatures by default, as well as the use of at least ZWNJ.

There are two unresolved concerns, and not minor ones.

One, if ligatures are suddenly enabled, what will be with all the 
existing texts that were written without ZWNJ inserted. Because of the 
nature of this issue it is *not* possible, to supply these via the 
layout system. That's a real problem for languages that have such 
requirements.

Two, many non-monospaced fonts are used in environments (such as text 
input widgets) where a more 1:1 relation between what is typed and what 
is displayed is appropriate.

Both of these essentially require that at least some ligatures can be 
globally disabled for certain documents or certain uses. Because some 
ligatures are required (and because this requirement varies by font 
style, not merely script) the old, "ligatures on, unless globally 
disabled, or overridden in script specific instance by character code 
(e.g as in lam-alif)" model was to simplistic.

Technology, if widely implemented, feeds back onto usage. It would be 
interesting to see whether widespread adoption of a simplistic ligatures 
on by default model would result in languages that now have prohibited 
ligatures to give up on this concept. Already, the inability of 
spell-checkers to handle unlimited compound nouns has had a noticeable 
impact on German spelling (books have been written on that subject...and 
"Word" is the villain).

A./