sub routine{

$prepage = "/path/to/page";

print "Content-type: text/html\n\n";
#open file:
open (PAGE, "$prepage") || die "Couldn't get prepage ched";
@prep=<PAGE>;
close (PAGE);

$tag =~ m/<!--..? -->/;

if ($tag eq '<!--a -->')  {
&suba;
exit;}

if ($tag eq '<!--b -->')  {
&subb;
exit;}

}