Depending on GETPOST index numbers is an exercise of
futility.  The LISTSERV(R) method of doing what you
want is to use the File Archives feature.  See section
8 of the List Owner's Manual for starters.  That way
users can issue

GET SCOUTS-NL xxxxxxx

commands (actually it can be in the more general form
GET fn ft fl)

--  co-owner:   INFOSYS, TQM-L, CPARK-L, ERAPPA-L, JANITORS, LDBASE-L, et -L
URL:mailto:[log in to unmask]                  "Are you a bandwidth bandit?"