More detailed programming available from this document. Starts: Page22, Advanced operating techniques. Most of this has not changed, even with the Legacy upgrades. The Complete guide to Command Control was part of the original Cab1/Command base sets.
The above mention control, limits coupler use and lighting sequence. Idea is: A combination of engines/locomotives assigned a TR (train) number operates as a unit, front coupler/rear coupler funtional, all other couplers do not function once the consist is established.
There is programming for:
(1.) Lead engine facing forward
(2.) Middle engines facing either way
(3.) Tail engine facing forward or backward.