What is the purpose of the Sound Group option?

In the ‘details’ of a soundwave in the ‘Sound’ section it refers to a ‘Sound Group’ . What is this and how does it differ from a Sound Class ??

SoundGroup is the very first steps towards an audio memory management scheme. The plan is that when assigning a sound to a sound group you will be able to specify how much memory the decompressed sounds in that group are allowed to occupy and using an MRU scheme sounds will be unloaded as needed.

At the moment it can be used to govern the thresholds at which to uncompress a sound in to memory versus using the real time decompression as it is played.

OK - interesting, Thanks!