Behaviour of \latinfamily

[Rebecca and Rowland]

>Rebecca and Rowland writes:
> > Ha ha very funny.  Done that.  Makes no sense to me at all.  If it did make
> > any sense to me, I wouldn't be asking, would I?
>it must make *some* sense....

No, it's more-or-less pure noise to me.  I've tried follow what goes on and
I've failed to make any sense at all out of well over 95% of it.  One or
two (no more) of the comments have helped me understand one or two commands
(no more).

The problem is that TeX code is *very* difficult to follow.  If there were
some indication of the flow of processing and the intended purpose of the
various bits of code, it might be possible for someone who's not a TeX
wizard to follow it.  As it is, it's currently a package for wizards only;
mere mortals like myself can make no sense out of it.  Note that it's not
just me: real live computer experts (Melissa O'Neill, for example) also
have trouble with fontinst.  Melissa's decided it's easier to write an
entirely new fount installation package in Perl rather than try and work
out how fontinst works.

[snip]
>because shape ui is not requested by \latin_family. it only asks for
>
>\def\latin_shapes{
>   \latin_shape{} {} {} {n}
>   \latin_shape{c}{c}{} {sc}
>   \latin_shape{o}{o}{} {sl}
>   \latin_shape{i}{i}{i}{it}
>}
>
>
>so he ui=it substitution is never activated.
>
>you are screaming now, aren't you?

Very nearly...   Yes, I've looked at the source code and I'm none the
wiser.  Can you explain two things:

1) What calls \latin_shapes and when.
2) What \latin_shapes does.

?

Thanks,
Rowland.