>We are using location.href but we were hoping we would not need to use session variables or have to pass another variable. That way the info is self contained and not reliant on what the other pages do. It sounds like this will not be possible.

You can also use a form and set the forms action property dynamically in your button click event:

document.formname.action = "pag2.asp"
document.formname.submit

Once you post the form to pag2.asp, the http_referer will be available.