$re = '/[EAQR]:\{((\d{3}\|?)+)\}(\^([-0-9.]+))?/m';
$str = 'E:{300}^2&E:{800}^4&A:{201}^-1&A:{200}^0.5&Q:{400|500|700}^2&R:{201|202}';
preg_match_all($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