functions

Specifies the layer functions and assigns mask numbers to the layers. The functions table is defined in the layerRules section of the technology file.

validLayers

Specifies the layers that you want to extract the connectivity through.

If the excludeLPPs constraint is used to specify the layer-purpose pairs to exclude from consideration, then a layer-purpose pair is excluded even if it is listed in validLayers.

validPurposes

Specify the valid layer purpose pairs.

viaDefs

Defines both standard and custom vias in the ViaDefs section of the technology file.

equivalentLayers

The equivalentLayers rule is used by the connectivity extractor mainly for legacy purpose. It allows two layers to be declared as strictly identical in terms of connectivity. For example, two layers that correspond to two different voltages of a metal can be declared as equivalent using the definition:

equivalentLayers( ((M1a drawing) (M1b drawing) M1c) )

This indicates that (M1a drawing), (M1b drawing), and all the purposes of M1c are in fact the same metal.

The equivalentLayers rule does not support derived layers. If a derived layer is included in the rule definition, a warning message is issued.

validVias

Cadence recommends not to define a validVias constraint in virtuosoDefaultExtractorConstraintGroup as it restricts the via definitions, which are parsed by the extractor to build the connectivity stack. However, in some technologies, such as those containing legacy via definitions, defining the validVias constraint can be useful.