QUERY: Indexing macros for TROFF ??

[Nancy Werlin]

I am looking for a set of macros that will create
an index in a TROFF document, preferably
by flagging to-be-indexed words and sticking them in a
buffer for future retrieval and sorting.
It doesn't have to be particularly sophisticated.

If anyone knows of such an animal, I'd very much appreciate 
learning about it.  Standard information: who sells/has
it, how it works, how much, whatever you know.
Thanks.

Nancy Werlin
EnMasse Computer Corp.