frames question

[Eric]

I want to pass a url parameter to a frame page.
In my index.html i have a line like this:
frame src="mp_page.html/?Section=4"
mp_page.html has this in it:
<!--#exec cgi="/cgi-bin/fill_in.cgi" -->

The problem is that fill_in.cgi just sees an empty
QUERY_STRING env variable when it runs

The frame creation page index.html is actually created
by an index.cgi so the parameter passed to mp_page is dynamic

How can i pass this URL param to the page mp_page.html so that
fill_in.cgi can get it in its query_string env var?
Thanks
Eric