A diagramming tool is provided that allows a diagram to be defined as a specialization of a “parent” diagram. The “child” diagram is defined based on the “parent” diagram such that the child diagram references the parent and contains only nodes and edges which represent differences between the instant diagram and its parent diagram. A diagram inherits all of the nodes and edges, and their properties, of its parent and adds, deletes, or redefines the nodes and/or edges that represent the differences or specializations.