When Onload isn't an option

[Gorilla Cheif]

This company I work for wants to create a web ad, and when the user clicks on it it takes you to their web page...nothing new, huh?
Well, the problem is the web page has an inset iframe and it needs to come up with a specific page in that iframe, but only when it's referred by this specific ad or page.

An onload javascript isn't really an option for an offsite ad.

How else could you solve this?

[RysChwith]

Make sure that the ad uses a particular query string in the URL (something like ?source=ad or whatever works). Add the onload in the target page to look for that query string and redirect the iframe to the appropriate page if it's there.

Rys