Thanks. I was half asleep. I have written a private function called is_set and forgot that it wasn't standard PHP
if register_globals is off:
if(isset($_GET['default2'])){
//do something like
echo 'default2 was in the GET string';
}
$_SERVER really is extraneous to the case, IMO. The question was "how do I deal with such and such type of URL get format". A GET problem best answered with GET tools.
For what it's worth, one can write secure code with register globals on, and insecure code with register globals off. One needs to be smart; register globals off is in no way a guarantee of security, and not necessarily even a help.
If you are truly concerned about security, assuming register globals off adds a magical layer of securitry would be a real mistake.