$re = '/^%(deft|reff|refd) ([a-zA-Z_](?:\w|\.)*)(.*?)(?:(?:%\.)|(?:$^[^%]))/sm';
$str = '%deft sym.1 and this continues
% until we # get to %.
%.
%.
This is not to be parsed
%refd sym.2 .%';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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