$re = '/^Event:\s+Task_(\d+)Error:(NO_ERROR|ERROR_(?:MINOR|\d+))(?:\w+:(\w+))?/m';
$str = 'Event: Task_01Error:NO_ERROR
Event: Task_01Error:ERROR_MINOR
Event: Task_02Error:NO_ERROR
Event: Task_03Error:ERROR_01Details:BadData
Event: Task_03Error:ERROR_MINOR';
preg_match_all($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