This paper describes a method which provides unified descriptive facilities for specification, logic analysis, decomposition and comparison of operational CAD system components, planned for, or having, the possibility to be modified to suit a particular application. A formalization of the CAD process is discussed in order to present it in the form of a closed directed graph which, in practice, can be easily translated into conventional operational forms such as algorithms, syntactic structures,simulation nets and first order predicate languages. The general design process model appears as a kind of procedural engineering knowledge. The model deals with the two abstract concepts of object specification and design procedure. These components are formulated using the set-theory postulated concept of transitive mapping closure of procedures. It provides for systematization and structural, functional, and behavioural analysis of operational components which, when put together, will operate in a required manner.