The edges of a graph can be partitioned statically into edge classes by providing an integer for each edge. Edges with the same integer form a class. These edge class numbers appear in the Select Edge Classes dialog box. Instead of the numbers the GDL specification can provide names for edge classes, e.g. if a syntax tree with type information is visualized the edge classes could be ``type edges'' and ``syntax tree edges''.
After selecting Expose/Hide Edges... in the Folding menu the Select Edge Classes dialog box appears (see Figure 9). The box shows all the edge classes present.
Edges of enabled edge classes and their target nodes are drawn in the graph window. Edges of disabled edge classes and all nodes accessable via these edges are not drawn and are not considered in the layout calculation of the graph.