Ok that was a very helpful. I've updated my sub and call like so

sub process(){

    my $processed = $_[0];
    
    return sub {
    
        if ( @_ ){
            
            print "Sub Process called\n";
            my ($colname,$colval) = @_;
            $colval =~ s/^&//; # strip leading & - this only occurs in
+ the 'ADDITIONAL field'
            print "Colname: $colname\n";
            print "Colvalue: $colval\n";

            
            # detect ADDITIONAL with multiple key value pairs.
            
            if ( index($colval,'&') >= 0 ){
                print "$colval contaisn & character - so it's the ADDI
+TIONAL field with multiple key value pairs";
                
                my @additional = split('&',$colval);
                foreach my $addval (@additional){
                    print "additional has pair: $addval\n";
                    
                    my @addpair = split('=',$addval);
                    print "$addpair[0] | $addpair[1]\n";
                    process->($addpair[0], $addpair[1]); # this doesn'
+t get called.
                }
                
            }
            
            # detect ors
            if ( index($colval,'|') >= 0 ){
                print "$colval contains pipe character for ORs";
            }

            # detect wildcards
            if ( index($colval,'*') >= 0 ){
                print "$colval contains whidcard character";
            }
            
            
        }
    
    }
    
}
[download]

Calling it now like

process->("TABLENAME",$TABLENAME) if defined($TABLENAME);
[download]

But, now that I'm calling split for each additional key/value pair in the additional column, I see the values get displayed by the print statement, but the sub doesn't get called.