Identify User Session Requests

In my iRule, I would like to identify user request for a page as unit of one request.

What I mean by that is, when a user browses to an URL (a Page Url), I want to process only this first GET request. Based on other stuff that page may have, the browser would make several requests belonging to the same above page request. I want to be able to identify that these are simply the sub request from an earlier main GET request.

Please advise.

Thanks Rajesh