OK, this will not enhance your regex-fu, and it may not be the most efficient (in terms of runtime resource allocation) solution, but it's a dead easy one to use, and very efficient in terms of programmer-hours spent on the problem. Following up on jasonk's suggestion, you don't even need it to be the case that the script doing the parsing is calendarview.pl. Simply feed the query string to a CGI.pm object and let it do the parsing for you:

#!/usr/bin/perl
                                                                      
+          
use CGI;
use strict;
use warnings;

# note you want everything after the ?
my $querystring='loginid=102138&month=04&year=2003&student_id=&user_ty
+pe=TUTOR&CalendarName=102138Academic&framename=top.index_main&session
+_number=618280744437303';
                                                                      
+          
my $q = CGI->new($querystring);
                                                                      
+          
foreach my $p ( $q->param() ) {
        print "Parameter $p : " . $q->param($p) . "\n";
}
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If not P, what? Q maybe?
"Sidney Morgenbesser"