$re = '/(\b\d{5})((##DEU-Akten|[PZ] ?DEU)|(##Schutzerstreckungen|W ?WOS)|(##Widerspruch|[BRK] ?([A-Z]{2}|[MZ][123]|R1|T[12])([-_]?([A-Z]{2}|[MZ][123]|R1|T[12]))?(-?\d+)?(\.?\d+)?)|(##mitLand|([PZGDWSEL]|[NVYTXCUAK]) ?((((HK-?CN)|(([A-Z]{2}|[MZ][123]|R1|T[12])(-?EP|-?EM|-?AP|-?OA)?))(-?WO|-?W\d+?)?|S))(-?\d+)?)|((##ohneLand|[NVYTXCUAK])(-?\d+)?))/m';
$str = '62877K';
preg_match_all($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