[verve_rat]

I don't really care that much (Labour LOL) but this might be a good place to start:

Originally Posted by European Broadcasting Union

http://tech.ebu.ch/docs/r/r128.pdf

The EBU, considering;
...
e) that an international standard for measuring audio programme loudness has been defined in ITU-R BS.1770 [3], introducing the measures LU (Loudness Unit) and LUFS (Loudness Unit, referenced to Full Scale)1;