CV - Configuration Variables
Every DCC decoder can be programmed to respond to a specific direction. Loco decoders also can be programmed to use 14, 28 or 128 speed steps, acceleration delay, braking delay, etc. Accesory decoders can change the time of output activation. The features are stored in special locations of internal decoder memory. These locations are called Configuration Variables or simply CV.
CV programming is done from Command Station in diferent modes of programming (direct, register, paged, PoM) not all decoders accept all programming modes so you have to check it in the decoder manual.
The main accepted CV for most loco and function decoders are: