This standard defines a language for describing both the software architecture and the execution platform architectures of performance-critical, embedded, real-time systems; the language is known as the SAE Architecture Analysis & Design Language (AADL). An AADL model describes a system as a hierarchy of components with their interfaces and their interconnections. Properties are associated to these constructions. AADL components fall into two major categories: those that represent the physical hardware and those representing the application software. The former is typified by processors, buses, memory, and devices, the latter by application software functions, data, threads, and processes. The model describes how these components interact and are integrated to form complete systems. It describes both functional interfaces and aspects critical for performance of individual components and assemblies of components. The changes to the runtime architecture are modeled as operational modes and mode transitions.