$re = '/(?:ID\s+)(\d{8})/';
$str = '... 12 ID 12345678 INDEPENDENT BOARD...
... 12 ID 87654321 (a.12(3)(b),45)...';
preg_match_all($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