Design object structures are of two types. Hierarchies of design objects such as those in a Functional Structure, Locational Structure and Pipe Part Structure or they may be design objects related to one another on the same level such as From and To Relations, a Process Object Relation and a Circuit Object Relation. In this way, design object structures are useful in indicating important design object-design object relationships. Functional, locational and pipe part structures are established by entering a Functional Parent, Locational Parent and Pipe System on a design object respectively. From and To relations, process object relations and circuit object relations are established by entering From and To, Process and Circuit Objects respectively.