# logical markup (was: Missing glyphs)

• To: math-font-discuss@cogs.susx.ac.uk
• Subject: logical markup (was: Missing glyphs)
• From: Ulrik Vieth <vieth@thphy.uni-duesseldorf.de>
• Date: Mon, 5 May 1997 11:30:01 +0200

Matthias Clasen:

> 4) Some control sequences (denoting different mathematical symbols) use
>    the same glyph in the plain LaTeX. The examples I came up with are
>    \backslash and \setminus and \Delta and \Laplace (well, this is not
>    actually in plain LaTeX, but it is a natural counterpart to \nabla and
>    in defining it there are currently no alternatives to using \Delta).
>    It might be a good idea to use separate slots for these symbols (even
>    if the glyphs are the same by default). Perhaps this issue is already
>    settled for \setminus throught the inclusion of \smallsetminus in MC.

As mentioned in Frank's reply, this issue is a difficult subject with
a somewhat vague boundary that can't be decided rigourously.  As for
\backslash vs. \setminus I wouldn't see the need for different slots,
whereas for \Delta vs. \Laplace it would indeed seem advantageous to
have separate slots as the design of \Laplace might vary depending
on the font designers preferences (greek Delta vs. geometric triangle).

In any case, it would seem very useful for document portability to
ensure a consistent logical markup based the symbol's functional
meaning rather than eventual appearence, possibly allowing for some
configuration at the macro level when several options exists.

For instance, in physics one might always want to write \vec{x}
regardless of whether the outcome is a letter with an arrow accent or
a bold or bold italics letter taken from a different math alphabet.
Similary, one might write \Laplace instead of \Delta or \triangle, or
something like \variation or \increment instead of \delta or \Delta.

I might eventually get back to writing up a more detailed proposal
concerning the requirements for functional markup in physics.

Cheers,
Ulrik.