Donald Arseneau asnd at triumf.ca
Thu May 28 20:58:38 CEST 2009

Dorothy Jammins <dorothy.jammins at yahoo.com> writes:

> Can this be used to combine subscripts in equations? I've tried but
> couldn't figure out how to ensure that the whole group would be in
> math mode and subscript.

The subscript designator (_) is not usually a macro, so
it isn't redefined.  If you make it an active character
with a macro definition, then sure, you would look ahead
for another _ character (but no need for \expandafter).

What are you trying to achieve?  I don't understand that
second sentence at all.  I would think you would need
to look beyond intervening superscripts.

By the way, ' (apostrophe) has a definition in math
that does ^{\prime} but it looks ahead for another '
and combines them to give ^{\prime\prime}.  Maybe
you just want to copy that definition.

--
Donald Arseneau                          asnd at triumf.ca