[PAYH] Move of CGI to PAYH - IFRAMEs

[#1]

I have some Home pages HTML which calls a PAYH PHP page using an Iframes query-string, e.g.
<iframe src="http://mydomainname/phpcode.php?parameter=blah">
This worked fine on CGI but now fails to pass the parameter when moved to PAYH  -  'blah' comes over as blank (actually a single space).
Anyone any ideas pls?
PS: Since query-strings are supposed to be treated in the same way as GET/POST parameters, I thought the problem might be related to the magic_quotes_gpc setting which (for some unaccountable reason) is ON in PAYH and upsets GET/POST calls containing  quotes, backslashes or nulls. But parameter 'blah' is a simple alpha character string...

[#2]

Could it be to do with Register Globals?  Do you explicitly get the query string in your script? ie

$parameter = $_GET["parameter"] ;

Phil

[#3]

Many thanks Phil - spot on!
It was some older PHP code which did not explicitly $_GET['parameter'] but had made the pre-PHP4.1 assumption that $parameter would be automatically set (i.e. the default register_globals setting was 'enabled').
Presumably PN had overridden the default register_globals setting ('disabled') in CGI's PHP 4.3
I am now off to check every other $_GET in all my PHP pages to ensure that there are specific assignments.