Historical symbol definition formatting

[Gavin Smith]

On Tue, Jul 26, 2022 at 09:00:30PM +0000, Werner LEMBERG wrote:
> 
> > There have been changes to @def formatting in the past.  There is a
> > ChangeLog entry
> > 
> > 2003-11-23  Karl Berry  <karl@gnu.org>
> 
> Almost twenty years ago...

Using variable-pitch fonts for function arguments goes back a long way.
I found it interesting to see the Lisp Machine Manual from 1981.

http://www.bitsavers.org/pdf/mit/cadr/chinual_4thEd_Jul81.pdf
(34 MB download)

This is from before Texinfo but can be seen to be from a predecessor.
Font conventions for definitions are described on page 3.
Main definition names are in a blacker fixed-width font, regular code
in a lighter font.  Function arguments are in (true) italics.
Keywords like "&optional" are upright, not blacker, and use the same
variable width font as general paragraph text.

I think it makes sense to use a heavier font for the definition names:
they are like headwords in a dictionary.  I expect had there been a
standard bold typewriter font with TeX then that would have been used
instead of bold or typewriter.