Attribute for <ISINDEX ...>
ACTION = "URL"

Usage Recommendation
don't use it

ACTION is a particularly bad idea. Even if you choose to use <ISINDEX ...> (which you shouldn't, use <FORM ...> instead), ACTION is a really bad idea. ACTION indicates that the query should be submitted to another URL instead of the current URL, which defeats the whole concept of <ISINDEX ...>.

this code	produces this
<ISINDEX ACTION="../cgi-bin/congress.pl">	this page