Thanks for your reply. I understand that the querystring is necessary in that case.
Actually, what I want is (almost) the same structure as the "mywebassist" from the webassist.com page.
For example, when I try to access to my userprofile.php page without logging in, I am redirected to the login page without that accesscheck paramater in the url, and once I'm successfully logged in, I am redirected to the previous page (userprofile.php).
So question is, how can I do that ?
Thanks in advance