>If you were typesetting in Fraktur, you had no choice but to use
>letter-spacing.  The use of italics became possible only after the
>abolition of Fraktur.

  In mathematics, variables are usually typeset in some kind of slanted
type (like italics), whereas contants (usually function names, and the
like) are usually typeset upright, even though tradition provides many
exceptions (like the numbers e and pi, which are contants usually typeset
in italics).

  It would in fact be a good idea of having a good set of upright and
slanted (both upppercase/lowercase) of fraktur and script styles for
mathematical purposes (the AMS-Fonts package does not provide it). For
example, when speaking about categories C, D, one would use say slanted
script, but when indicating the functor category Fun(C,D), the name "Fun"
would be typeset in upright script.

  Hans Aberg