Re: [Freefont-bugs] ligatures

[Karl Berry]

    1) What applications use the ligatures?  

It is certainly possible to end up using them in TeX, one way or another.
I imagine in OpenOffice or whatever, they could also be used, if you
insert the character code where the st ligature is :).

    2) In the TrueType fonts

This is another topic, but is TrueType the main target format at this
point?  (I hope not.)

    3) What is the intent of the distinction between discretionary vs
    mandatory ligatures?

Probably just what you said.

    Is it that some scripts are unreadable without ligatures?

Yes.  Arabic and related languages, among others, have a complex concept
of ligatures, which is necessary for even minimally acceptable
typesetting.

    Myself, I think the 'ffi' etc ligatures are important to good
    typesetting, 

Certainly.  (Well, depending on the font design, a few fonts are
intentionally designed so that the ffi et al. look ok without
ligatures.  Anyway ...

    almost never sees the conjoined 'st' ligature.  Can that distinction
    be made in the font as well?

I don't know, perhaps in OpenType?  I don't know if there are standard
features relating to this.

In any case, I'm most familiar with TeX's tfm metric files.  These can
specify the ligatures used "by default"; ordinarily ffi and the like
would be, while st would not be.  The user would type \st{} in the
document or some such to explicitly specify they wanted it.

Best,
karl