$re = '/(?:<a\s+(?:[^>]*)?href="|(?!^)\G)\K.*?([A-Z]?\d{5}).*?(?=")/i';
$str = '<a href="/uploads/2014/04/Draft-99990-Details.doc">Draft 99995 Details</a>
<a href="/uploads/2014/04/01090-vs-G01010-series.pdf">01095 vs G01015 Series</a>';
preg_match_all($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