$re = '/[A-Z]{6}[0-9LMNPQRSTUV]{2}[ABCDEHLMPRST]{1}([1-9]|[12][0-9]|3[01]|4[1-9]|[56][0-9]|7[01]|LMNPQRSTUV){2}[A-Z]{1}[0-9LMNPQRSTUV]{3}[A-Z]{1}/m';
$str = 'MSLNDR00M19H501I
CNTMNL62C69H501O';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($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