[tex-eplain] Indexing causes erors.

[Karl Berry]

      \sidx{polar bear}
      \sidx{bear}[polar]
      \sidx{Ursus maritimus}
      Polar bears live only in the northern Arctic.

    without having to worry about adding `%' after each \sidx{...}.

Precisely.  Ignoring trailing spaces was completely intentional and I
still think it is the right thing to do.  Anyway, right or wrong, the
default behavior should not be changed now IM(NS)HO.

If it is really desirable to preserve such spaces,
it seems it would be easy enough to add a command, say,
\sidxnoignorespaces
which would have the effect of nullifying the final \ignorespaces so
that trailing spaces are not ignored.  (Make the final \ignorespaces
into a macro which \sidxignorespaces resets to \relax, etc.)

karl