What's this “Album artist” tag iTunes uses? Any way to set it using java?

Question

iTunes uses an ID3 tag called "Album Artist", and for one album to be actually grouped as an album in iTunes, both the Album Name and Album Artist must be the same.

As far as I'm concerned, Album Artist isn't an official ID3 tag, and from the ID3 libraries I've seen so far, none supported "Album Artist".

Does anyone know more about this strange tag, and how to set it in java (or with any command line utility).