$re = '/^((NO)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{3}|(NO)[0-9A-Z]{13}|(BE)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}|(BE)[0-9A-Z]{14}|(DK|FO|FI|GL|NL)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{2}|(DK|FO|FI|GL|NL)[0-9A-Z]{16}|(MK|SI)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{3}|(MK|SI)[0-9A-Z]{17}|(BA|EE|KZ|LT|LU|AT)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}|(BA|EE|KZ|LT|LU|AT)[0-9A-Z]{18}|(HR|LI|LV|CH)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{1}|(HR|LI|LV|CH)[0-9A-Z]{19}|(BG|DE|IE|ME|RS|GB)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{2}|(BG|DE|IE|ME|RS|GB)[0-9A-Z]{20}|(GI|IL)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{3}|(GI|IL)[0-9A-Z]{21}|(AD|CZ|SA|RO|SK|ES|SE|TN)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}|(AD|CZ|SA|RO|SK|ES|SE|TN)[0-9A-Z]{22}|(PT)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{1}|(PT)[0-9A-Z]{23}|(IS|TR)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{2}|(IS|TR)[0-9A-Z]{24}|(FR|GR|IT|MC|SM)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{3}|(FR|GR|IT|MC|SM)[0-9A-Z]{25}|(AL|CY|HU|LB|PL)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}|(AL|CY|HU|LB|PL)[0-9A-Z]{26}|(MU)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{2}|(MU)[0-9A-Z]{28}|(MT)[0-9A-Z]{2}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{4}[ ][0-9A-Z]{3}|(MT)[0-9A-Z]{29})$/';
$str = '';
preg_match_all($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