$re = '/^(?i)[T]20[0-9]{2}[0-1][0-9][0-3][0-9].\d{4}$/m';
$str = 't20160307.0001
T20160201.0003
y20160202.0001
T20163022.11157
t2016o302.0001
T21160302.0001';
preg_match_all($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