$re = '/\|[ ]?(a|b|d|f|j|k|m)([ ]*\=[ ]*)((?![\r\n]+\|)[0-9a-zA-Z, \[\]:\|\r\n\t])+/';
$str = '{{TemplateX
| a =
Foo bar
Blah blah
Fizbin foo
Ipsum lorem
|b =1
|c = 0fillertext
|d = 1alphabet
| e =
| f = 10: One
Hobbit
| g = aaaa, bbbb,
cccc,
dddd
|h = 15000
|i = -15000
| j = Level 4 [[domain:filk|Songs]]
| k =7 fizbin, 8 [[domain:trekkies|Shatners]]
|l =
|m =
}}';
preg_match_all($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