sub generate_pmd_form {
   ...
   if(level($monk) < $n) { 
      $pmd_form->add_submit("This post is about Perl");
      $pmd_form->add_submit("This post is about the perlmonks website");
   }
   ...
}
...
sub process_pmd_submit {
   if($form_submit eq "This post is about Perl") {
      print err_message("wrong forum; you meant SOPW") 
      return generate_pmd_form();
   }
   ... normal submission acceptance ...
}