Does anyone know what the 3 "codes" are for, in the (sorry blurry) photo? The letter codes to the left are:

A
T/U
T

I wonder what they mean, and what the hand written codes mean in the spaces to the right, next to these letters? Thanks a lot for any comments! 😀

Picture "screen grabbed" from Swaaye's Wikipedia entry for the Ensoniq Soundscape S-2000 sound card: