The Software Engineering Facility (SEF) is a system for software engineering which is specifically designed to support the development of well-engineered software. However, it is not an operating system. Unlike operating systems such as OS/370, EXEC 8, and others, the SEF is not meant to support the execution of applications programs, just as the ordinary operating systems are not intended to specifically support the development of well-engineered applications programs. The SEF, in fact, will run under and use the facilities of such operating systems. It, then, is easily transferable and can be used with vaxious hardware/operating system configurations where it will provide a host-independent software development system. In such a role it will provide to the software developer standard facilities across a variety of host systems.