Adam, that's not quite accurate about the '?'. If a question mark follows a quantifier (*?, +?, {min, max}? or ??) in a regex, it makes it "non-greedy". Consider the following code.

# 3 spaces, a tab, 3 more spaces, another tab and 3 more spaces (repre
+sent by chr() for clarity)
$test = chr(32)x3 . chr(9) . chr(32)x3 . chr(9) . chr(32)x3;

($first = $1, $second = $2) if $test =~ /(\s*)\t(\s*)/;
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In this case, the first (\s*) will be greedy and attempt to match as many characters as possible. $first will contain 3 spaces, a tab, and 3 more spaces. $second will contain 3 spaces. However, by adding the question mark, we make it non-greedy.

($first = $1, $second = $2) if $test =~ /(\s*?)\t(\s*)/;
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This means that (\s*?) attempt the smallest match possible that satisfies that above regex. In this case, $first contains 3 spaces and $second contains 3 spaces, a tab, and 3 more spaces. The '?' does not mean "aka zero".

Incidentally, most regexes ending in (.*?)$/ (like the one in the original post) have a superfluous ? because there is no way to make that statement non-greedy, since it's forced to match to the end.