| DEF (Design Exchange Format) is a recent interchange format for CAD systems. It is often combined with LEF (Library Exchange Format) files. For more information on reading and writing DEF or LEF, see Section 3-9-2 and Section 3-9-3, respectively. DEF options are controlled with the DEF Preferences (in menu File / Preferences..., "I/O" section, "DEF" tab). This dialog controls whether DEF reads physical and/or logical information. If a type of interconnect is not checked, the DEF input reader ignores those arcs.