Networked systems inherently must be considered as highly complex systems. In order to guarantee high quality and highly efficient results while designing and applying networked systems the degree of complexity to be handled by the system designer must be decreased to an acceptable level. The methodology to achieve this goal is to hide details in software/hardware support drivers.The subsequently presented paper gives an overview on CAL = CAN Application Layer. CAL has been defined in Europe by industrial manufacturers of CAN networked controller systems. As the CAL features and characteristics are of generic type the gained results may be of interest for being considered in automotive applications. Furthermore CAL can be regarded as a generic higher layer for autobus protocols whether it is CAN, VAN, J1850, … Therefore the ideas presented in this paper may be a point of discussion for the design of a generic automotive communication layer.