If you have a MAIN php script which you don't want to be included by other scripts, you could use this function. For example:main.php:<?phpfunction blockit(){ $buf = get_included_files(); return $buf[0] != __FILE__;}blockit() and exit("You can not include a MAIN file as a part of your script.");print "OK";?>So other script couldn't include main.php to modify its internal global vars.