This is a discursive paper. That is, it shows some formulas (but only as examples so that the reader may be convinced that there is, perhaps, some substance to our claims), no theorems, no proofs. Instead it postulates. The postulates are, however, firmly rooted, we think, in Vol.3 (`Domains, Requirements and Software Design') of the three volume book `Software Engineering' (Springer March 2006) [6, 7, 8]. First we present a summary of essentials of domain engineering, its motivation, and its modf abstractions of domains through the modelling of the intrinsics, support technologies, management and organisation, rules and regulations, scripts, and human behaviour of whichever domain is being described. Then we present the essence of two (of three) aspects of requirements: the domain requirements and the interface requirements prescriptions as they relate to domain descriptions and we survey the basic operations that "turn" a domain description into a domain requireme...