As custom software was developed to solve specific problems, a pattern began to emerge for the functions required by many CAD applications. The typical CAD application deals with the specification and assembly of predefined objects to create discipline-specific functional infrastructure. For example, electric utilities combine wire, transformers and switches to create a power distribution system.
Petroleum refineries utilize pumps, tanks, pipes and valves to handle various chemical processes.
In each case, there is a logical design for the system along with a standard technique for creating construction drawings. The first is called SnapMap, a system for managing digital maps and facility records of utility companies. These products are detailed in the following sections. Broad applications of these technologies are currently under development for a variety of purposes. SnapMap provides an interactive graphics environment that automates the drafting of utility maps, manages the data attributes of equipment shown on the maps, and maintains network topology to simulate utility system behavior under actual or planned operating conditions.