question about tracking

my question is about tracking the previous page.

there is a form(ex=subscribe.asp) which is an asp page where users can sign up for newsletters. this asp file calls a php file in the form action which i have written and this php file processes information user entered and inserts to the database. this works fine. in the website there are numerous pages from which a user can click on an image and be redirected to subscribe.asp and fill in the form.

I need to know which page the user was before subscribe.asp ex = aboutus.asp, contactus.asp etc.

please provide the code by which i will be able to track the source of the previous page.

NOTE = The form page can only be an asp file as i am using a cms which does not support php files due to this the form page will only be an asp file

thanks.

re: question about tracking

The following returns the previous URL
[PHP]$url = $_SERVER['HTTP_REFERER'];[/PHP]