This page mentions various terms used by plumbers, and people who are interested in toilets, and will say what they mean.
A-S: Short for American Standard, or Armitage Shanks
Flushometer: Alternate term for flush valve
GPF/Gallons per flush: how much water the toilet uses when flushed once in gallons
LPF/Liters per flush: how much water the toilet uses when flushed once in liters
Flush ell: Short for flush elbow
K of K: Short for Kohler of Kohler
MaP: Maximum Performance testing
A-S: Short for American Standard, or Armitage Shanks
Flushometer: Alternate term for flush valve
GPF/Gallons per flush: how much water the toilet uses when flushed once in gallons
LPF/Liters per flush: how much water the toilet uses when flushed once in liters
Flush ell: Short for flush elbow
K of K: Short for Kohler of Kohler
MaP: Maximum Performance testing