note 106581 added to tutorial.useful

Note that for historical reasons, most browsers (including IE) identify themselves as Mozilla, so this keyword will not do for identifying an actual Mozilla browser. ---- Server IP: 69.147.83.197 Probable Submitter: 173.70.72.132 ---- Manual Page -- http://www.php.net/manual/en/tutorial.useful.php Edit -- https://master.php.net/note/edit/106581 Del: integrated -- https://master.php.net/note/delete/106581/integrated Del: useless -- https://master.php.net/note/delete/106581/useless Del: bad code -- https://master.php.net/note/delete/106581/bad+code Del: spam -- https://master.php.net/note/delete/106581/spam Del: non-english -- https://master.php.net/note/delete/106581/non-english Del: in docs -- https://master.php.net/note/delete/106581/in+docs Del: other reasons-- https://master.php.net/note/delete/106581 Reject -- https://master.php.net/note/reject/106581 Search -- https://master.php.net/manage/user-notes.php