note 87802 added to language.variables.variable

error_reporting(E_ALL); $iNum = 123; //a variable with the value of 123 $$iNum = '456'; // $123 is your variable name, this would normally be invalid. echo '$$iNum value is ',$$iNum; The output is: $$iNum value is 456 Variables must be named using only letters (a-z, A-Z), numbers and the underscore character; their names must start with either a letter or an underscore, and are one of only two identifier types in PHP that are case-sensitive. As per PHP "$123" is an invalid variable, then how the value of "$$iNum" is printed on the browser without any error? is this a bug in PHP? Note: Tested on "PHP Version 5.2.4-2ubuntu5.4, Apache 2.0 Handler " ---- Server IP: 203.199.69.133 Probable Submitter: 59.162.2.138 ---- Manual Page -- http://www.php.net/manual/en/language.variables.variable.php Edit -- https://master.php.net/note/edit/87802 Del: integrated -- https://master.php.net/note/delete/87802/integrated Del: useless -- https://master.php.net/note/delete/87802/useless Del: bad code -- https://master.php.net/note/delete/87802/bad+code Del: spam -- https://master.php.net/note/delete/87802/spam Del: non-english -- https://master.php.net/note/delete/87802/non-english Del: in docs -- https://master.php.net/note/delete/87802/in+docs Del: other reasons-- https://master.php.net/note/delete/87802 Reject -- https://master.php.net/note/reject/87802 Search -- https://master.php.net/manage/user-notes.php