An approach to software design representation which is consistent with the concept of engineering blueprints is presented. The main criteria for software engineering blueprints are defined and a network scheme of graphical representation is considered through an overview of Petri net techniques. The concept of an abstract process (AP) is introduced as the basic element of system representation. An abstract process network schema of software design representation is developed and supported by an algebraic system of notation. Methods of AP-net construction are presented and illustrated by examples. The advantages of using the proposed approach in different phases of software engineering are pointed out and the main directions for further research have been identified.