This document is a companion document to SAE AS4893 “Generic Open Architecture (GOA) Framework Standard” and provides an overview and rationale for SAE AS4893. The GOA Framework establishes an architectural framework to assist in the application of open systems interface standards to the design of specific hardware/software systems. The GOA Framework standard is intended for use by both system designers and system implementers in the development of open systems architectures. It is intended that domain specific guidelines be developed to provide clarification for application of the GOA Framework. The Generic Open Architecture (GOA) Framework was initially developed by the SAE to provide a framework which could be used to classify interfaces needed in airborne avionics systems. At the time of the development of the GOA Framework, development of such a classification was considered crucial to the application of open systems standards to military avionics.