isset bug?

Ok, here's the deal. I like to use $_GET and $_POST variables without values to notify my scripts that some action must be taken. For example, given the following URL: http://blahdomain/blah.php?productid=1&edit or given the following form element: <input type=hidden name="edit"> My blah.php script will check if edit set using the following line: if (isset($_REQUEST["edit"])) { .. } and then it will take the appropriate actions (lets just say its updating a record in the database). Locally I am running PHPv4.3.2, and everything works fine. I have been working on a large web-based application for the last month, and yesterday I put it up live. Our host unfortunately runs PHPv4.2.1 and I have no access to the conf files (those bastards) and globals are set to on. Low and behold, the isset function returns false when a $_POST or $_GET variable is passed but contains no value, which would be exactly the same thing as checking the variable itself: if ($_REQUEST["edit"]) { } What I want and needed to do was check for the existance of the variable, not whether it has a value. So is this a bug, a feature or just some random happening? Thank guys PHP ROCKS