[PS2] What Version of Step Mania is the In The Groove 2 Beta Based On?

Recently I've been playing around with customizing songs and various settings of the PS2 version of the original In The Groove, but have been growing increasingly frustrated with the rigid limitations imposed (custom song limitations and gameplay modifiers).

After shopping around inside what I can see of the ITG 2 Beta, I believe there could be a great deal more you could crack into (restoring USB profile save support, custom song loading off USB, unlocking additional game modifiers) if I could only determine which version of SM it is based off of.

Can anyone shed any light on this?