The main subjects here are

NMRA DCC = Digital Command Control according to the standards and RPs of the National Model Railroad Association. Especially about decoders.

and the FREMO Absolute Block

What, the guy plays with the model railroad? Yes, and very seriously with time table and way bills on long stretches of track (>100m) with many stations and yards and real dispatchers You don't understand that at all? Then You should have look at it on a meeting of the FREMO. But be warned: It is absolutely addicting.