By default, MakeIndex outputs `, ' after each term in the index. To change this, you can add the following to your MakeIndex style (`.ist') file:
delim_0 "\\afterindexterm " delim_1 "\\afterindexterm " delim_2 "\\afterindexterm "
Eplain makes \afterindexterm equivalent to
\quad.
You can also change the keywords Eplain recognizes (see section Modifying index entries):
\idxbeginrangeword
\idxendrangeword
\idxseeword
\idxseealsoword
You can also change the magic characters Eplain puts into the
`.idx' file, in case you've changed them in the .ist file:
\idxsubentryseparator
\idxencapoperator
\idxbeginrangemark
\idxendrangemark
There is no macro for the actual (`@' by default)
character, because it's impossible to make it expand properly.
Finally, you can change the (imaginary) page number that "see also"
entries sort as by redefining \idxmaxpagenum. This is 99999 by
default, which is one digit too many for old versions of MakeIndex.