Towards the achievement of quality in specifications

The task of requirement capture is to articulate the end-users´ stated or implied needs in a form which is unambiguous and can serve as the basis of objective quality assurance. A formal statement of the features and characteristics of the future system is the specification. By drawing out the implications of this statement in some way, such as by prototyping or reasoning, the user is helped to test whether the specification captures, completely and consistently, both the stated and the implicit needs. In the case of complex systems, it is necessary to draw a more precise distinction between those external features of the system, functional or otherwise, which are direct representations of the user´s needs, and those internal properties which the supplier can select or control. Using systems concepts, the former are referred to as behavioural properties; the latter are the structural characteristics of the system. Quality assessment can only be accomplished through measurement and it should be intrinsic to a specification method rather than an adjunct. It should guard the quality of the specification at each level before further design refinement is attempted. Bearing these considerations in mind, the paper outlines a method of specification and design for complex systems which incorporates a measurement prototype