Hi Mike,
I'm not sure why but newer versions of the SDK documentation seem to have lost some of this information. I keep copies of the older refdb.chm file for this reason.
From the 8.81 SDK:
C = Customer
A = Account
S = Vendor
P = P.L.A
T = Tax
D = TDS
So the C, A and S values match the enumeration that Alejandro has posted above. The others, I think, are for certain localisations (we don't use them on our sites).
Kind Regards,
Owen