Well, sure, calligraphers do it all the time. If you want to see it in
type, look at the styles Adobe sometimes calls "Extras" -- or the
"Swash" varieties of italics, and so on.

You won't see it much in metal type because each little variant has to
be cut individually (in all the sizes), and you won't see it in Linotype
or Monotype because there's a limited number of slots in each batch of
matrices (just like electronic fonts are generally limited to 255

For about two weeks some years ago, there was something called "GX" that
was going to use more-than-8-bit characters to get lots of variety, and
I heard that a Dutch team made an Arabic GX font that could do almost as
much as a street-corner scribe in Cairo. But we don't hear much about GX
any more ...

Macintosh System X has a capacity something like that. I saw a bit of a
demonstration back in April.

Gerald Lange wrote:
> Dear Peter
> No, perhaps more like a "beak" but rather than being fixed, like a
> beak, the tongue was lengthened or shortened to fill in, optically,
> the word spacing.
> Though your response may indicate a possible origin of the practice.
> Horizontal letterform stretching is another aspect of word spacing.
> This is a component of some of the TeX research I've seen, but the
> amount of variance in a character is limited by its shape and to an
> extremely small percentage (since it must not be visibly detected).
> The attempt is to provide a refined mathematical and automatic means
> of adjusting word spacing.
> The variable tongue is an alternative solution. But very hard to find
> any studies on, occasional reference to, etc. but that's about it.
> Thanks
> Gerald
> --- In qalam@..., "Peter T. Daniels" <grammatim@...> wrote:
> > Gerald Lange wrote:
> > >
> > > Hello members
> > >
> > > I'm looking for any information regarding the variegated "tongue" of a
> > > letterform or character. Used for optical word spacing. Apparently
> > > common in manuscript bookwork, early printed books (specifically,
> > > B42), and surprisingly, some references to TeX.
> > >
> > > Anyone?
> > >
> > > Gerald Lange
> >
> > ??
> >
> > Are you maybe referring to the fact that e.g. some Hebrew letters can be
> > stretched so they reach the left margin of the line?

Peter T. Daniels grammatim@...