ABSTRACT
The term constraints refers to all non-performance requirements, that is, requirements which cannot be determined from functions. Whereas performance requirements establish how well a system or subsystem should perform, constraints define the limits on that performance. As we have noted, definitions differ among systems engineers. For example, MIL-STD-961D (1995) uses the term constraints for a limited set of design constraints. The present definition, though, is preferred for clarity and simplicity.
