Modern air vehicles consist of many subsystems, traditionally managed as a federation of independent subsystems. Advances in control technologies, digital electronics and electro-mechanical hardware, provide potential opportunities to integrate subsystems for future aircraft. This document does not define any particular integration strategy. Its purpose is to provide information about traditional federated subsystems from the functional, control, resource, and hardware perspective. To be able to integrate subsystems, one must have a basic understanding of the subsystems, and this document provides an introduction or starting point for initiating the integration process.