$re = '/value="(\d+),(\d+),(\d+),(\d+)"/m';
$str = '<classifier id="box-geometry" value="476,736,703,997" />
<classifier id="box-geometry" value="476,736,703, 997" />
<classifier id="box-geometry" value="476, 736, 703, 997" />';
preg_match_all($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