> For the base fonts I agree this makes sense, but for top level fonts (i.e.,
> the ones which TeX/Omega actually works with) it is mainly a nuisance. It
What do you mean with "base fonts" and "top level fonts"?
> also goes against much of the philosophy in LaTeX as you end up with for
> each character separately specifying what it should look like rather than
> what it logically is.
I think we are speaking about different things. When you write a document
you use the logical value (eg, "fi") and TeX converts it to the
corresponding glyph (ie, the fi ligature).
The same should apply to, say, Greek. If I write "barbaros" [well,
imagine it written in Greek] using the same beta, sometimes I would like to
see the first one using a differenf glyph from the second one (a medial
beta, not used currently). That can be done with ocp's -- the file ell.fd
defines a language property named beta with two possible values (oneform
and twoform) which specifies how beta will be rendered. That can be done
with tfm ligatures too, I think, but I cannot change how its rendered from
my document, except if a create new vf/tfm files for every font.
> Now I don't understand. Are you saying that there is an OCP, but that it
> never changes anything?
It changes things, but TeX was built in such a way that only the font
encoding (ie, the encoding used in the tfm file; ie, the final form after
every single ocp has been processed) is used when hyphenating
words. (And this problem has not been solved by Omega.)