1. A method for processing a computer generated model of a real-world utility network composed, in part, using an extended network part schema, the method comprising: retrieving the extended part schema, wherein the schema identifies a collection of network parts included in the model and wherein each network part is identified by a global identifier; parsing the schema to identify a first set of global identifiers associated with hard-coded part types and attributes defined in a CAD application; associating the network part types and attributes identified by the first set of global identifiers with an enumeration value hard-coded into the CAD application; parsing the schema to identify a second set of global identifiers associated with extended part types and attributes not defined in the CAD application; and dynamically assigning each of the network part types and attributes identified by the second set of global identifiers an enumeration value selected from a range of values outside of the values hard-coded into the CAD application.