This means mainly not accepting overlong representations and not
allowing invalid bitmasks.
darcs-hash:20071231114623-a4fee-0006712f7f3e5db565b50d38eeb32674e063c49e
This is a bit of a hack, because the static lookup data this encoding requires brings template haskell to it's knees. So I've got a program that generates a haskell module file from the XML mapping.
darcs-hash:20070823034759-a4fee-883359c8951d4376fc2d783cd7be352d6c5b2111