In Ashby's terms, each subsystem has adapted to the environment formed by all other subsystems. Benchmarks provide a method of comparing the performance of various subsystems across different chip/system architectures. Several subsystems and components were also redesigned to reduce maintenance demands. Systems theory considers the nervous system's organisation into interacting subsystems. CM emphasizes the functional relation between parts, subsystems, and systems for effectively controlling system change. The cost varies because of the interfaces that subsystems are exporting. The PNS is divided into three separate subsystems, the somatic, autonomic, and enteric nervous systems. The entropy of inhomogeneous systems is the sum of the entropies of the various subsystems. UPW systems consist of three subsystems&colon; pretreatment, primary, and polishing. Another motivation for considering density matrices comes from consideration of systems and their subsystems. SDL functions are categorized under several different subsystems. This can be useful for decoupling subsystems of large application into separate processes. These signal-processing tasks require intricate interplay between a variety of functional subsystems. Capabilities include airframe, landing gear, APU and other subsystems. There are several kernel internal APIs utilized between the different subsystems.