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.

DEF interconnect is specified in the NETS and SPECIALNETS sections. Typically, the SPECIALNETS are pre-routed geometry (physical) and the NETS are routed geometry (physical) or unrouted information (logical). Check "Ignore physical interconnect in NETS section" to skip any routed arcs (physical) found in the NETS section. Check "Ignore logical interconnect in SPECIALNETS section" to skip any unrouted arcs (logical) found in the SPECIALNETS section.

Physical NETS are read as arcs on different layers that connect the circuitry. This can take a lot of time to place. If it takes too long, and if the connectivity information is not needed, check "Use pure-layer nodes instead of arcs" to use pure-layer nodes instead of arcs.

When unknown cells are referenced by the DEF file, an error is issued. If "Make dummy cells for unknown cells" is checked, the system resolves the problem by generating the appropriate cell.