GET/POST whitespace stripping behavior

Hi, I have a general question in regard to the PHP variable normalizing. Obviously, leading whitespace in a variable is stripped, but why is trailing whitespace converted to underscores? Example: /?foo=bar&+fooo=blah&foooooo+=ljalskdf results in: array(3) { ["foo"]=> string(3) "bar" ["fooo"]=> string(4) "blah" ["foooooo_"]=> string(8) "ljalskdf" } I can understand why one would want to convert middle spaces (like in "foo+bar") to underscores, but shouldn't trailing spaces be stripped instead? Am I missing something? Regards, --ck