About boundary characters

[barbara beeton]

There's one genuine zero-width character that I can think of:
the "\not" character in the cmsy font.  Check it out in the
comprehensive symbols list (p.232 in the version I'm looking at):
   "... like \not, puts a slash over the subsequent mathematical
    symbol."
 						-- bb

On Wed, 18 Sep 2019, Tomas Rokicki wrote:

> A minor correction:  characters *can* have zero width.  A characterwith a
> zero *index* to the width table does not exist, but one of the
> other entries in the width table can certainly be zero.
> 
> (I don't know if any such characters exist, off-hand.)
> 
> -tom
> 
> [...]