如何覆盖元标记？

www.something.com/?page=single_page

$conlibrary=\"play/pages/\"   ;                   
IF(!isset($_GET[\'page\'])){ 
    $page = \'deafault\'; 
} ELSE { 
    $page = $_GET[\'page\']; 
    $findme = \'&\';
    $pos = strpos($page, $findme); 
    IF ($pos ===true) { 
        $data = explode(\"&\", $data); 
        $dest =$conlibrary.\"/\".$data[0].\".php\"; 
        IF (file_exists($dest)) {
            $page = $_GET[\'page\']; 
        } ELSE {
            $page = \'404\'; 
        } 
    } ELSE { 
        $dest =$conlibrary.\"/\".$page.\".php\"; 
        IF (file_exists($dest)) {
            $page = $_GET[\'page\'];
        } ELSE {
            $page = \'404\'; 
        } 
    } 
} 

include($conlibrary . $page .\".php\");