querystring and frameset issue

Can somebody tell me how to pass a value between two php pages within a frameset. I have a simple two column framset: navbar on the left, content on the right. I have two pages that are displayed in the content area. Both are PHP pages. I would like to pass an ID value from the first page(a list page) to the second (a detail page). I tried renaming the frameset page and associated links with a php extention but that didn't work. The link from the list page does contain the ID var in the querystring but it is not recieved in the display page where I try to echo the querystring var. Any ideas? Does the frameset page need to have a php extention? Thanks. Irvin <><