CAS: Car Access System
WARNING: This page does not describe the selected car, but rather 45 other vehicles, including the 2016 BMW M5, 2016 BMW 550i xDrive, 2016 BMW 550i, 2016 BMW 535i xDrive, and 2016 BMW 535i. However, it is still accessible from the selected car via links, so may be relevant.
The Car Access System (CAS) controls access into the vehicle (central locking system) and access to vehicle functions (e.g. key identification, electronic immobiliser, engine start release).
The CAS control unit is the master control unit. It is therefore the CAS control unit that issues the release.