This from the Legacy 1.5 manual. Still clear as mudd
CAB 1 MODE
+or - Relative commands
Lionel Power Masters
Lionel TPC’s
Engine or Track settings
Electric RR or EOB speed control
TMCC MODE
32 absolute speed commands
Lionel Locomotives & Accessories
Electric RR or EOB speed control
REL 100 MODE
100 Relative speed commands
Electric RR or EOB speed control
Lionel OEM’s (with Electric RR cruise)
LEGACY MODE
200 absolute speeds
Lionel LEGACY engines
Lionel LEGACY accessories