Use of the DUNION attribute on DESIGN elements, for example, FRMW or STRU is described. Refer to Controlling Edge Representation in DRAW for further information. The DUNION values are used during an UPDATE DESIGN process to determine whether common edges between FRMWs are drawn or omitted. However it is possible to ignore all DUNION values by setting the View's IGNDUN attribute (Ignore Dunion) to TRUE. (The default value is FALSE). After changing the IGNDUN attribute an UPDATE DESIGN is required.