note 54573 added to function.is-null

Can you tell me what's the different between null or NULL. Thank You. ---- Manual Page -- http://www.php.net/manual/en/function.is-null.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+54573 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+54573&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+54573&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+54573&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+54573&report=yes&reason=useless Delete: non-english -- http://master.php.net/manage/user-notes.php?action=delete+54573&report=yes&reason=non-english Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+54573&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+54573&report=yes Search -- http://master.php.net/manage/user-notes.php