$re = '/^\[\[\%([A-z0-9\-]+)\?\s+\&namespace\=\`(.*)\`\s+\&topic\=\`(.*)\`\]\]/Uis';
$str = '[[%mt4se-amuk-tradeterminal-4-p-59? &namespace=`main_uk` &topic=`TradeTerminal`]]';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php