Multiple-unit train control in the context of "Distributed power"

A multiple-unit train (or multiple unit (MU)) is a self-propelled train composed of one or more carriages joined, and where one or more of the carriages have the means of propulsion built in. By contrast, a locomotive-hauled train has all of the carriages unpowered.

An implication of this is that all the powered carriages needs to be controllable by a single engineer or driver, which is a case of the broader concept of multiple-unit train control. In other words, all "multiple units" employ some variation of multiple-unit train control. In the broader context "unit" means any powered rail vehicle, including locomotives (that does not carry cargo) and powered cargo-carrying carriages. In the context of this article, "unit" refers specifically to the latter only (whether the cargo is passengers or some other cargo).

Push–pull is a configuration for locomotive-hauled trains, allowing them to be driven from either end of the train, whether having a locomotive at each end or not.

A push–pull train has a locomotive at one end of the train, connected via some form of remote control, such as multiple-unit train control, to a vehicle equipped with a control cab at the other end of the train. This second vehicle may be another locomotive, or an unpowered control car. This formation meant that the locomotive would not have to run-around at the end of a journey before returning.