The Design Rule Check is part of the PDK. Both the Magic and OpenLane tools make use of it.

It contains rules that check things like:

• The gate of the MOSFET are the correct dimensions,
• Wires on the metal layers are not too narrow and not too close,
• Check that MOSFET gates are protected if they have long connecting wires - this is called an antenna rule.

There are a few thousand rules in the Skywater130 PDK DRC. As the process/node gets smaller, the number of rules increases.

You can find out more about the DRC checks performed by OpenLANE in Mohamed Shalan’s OpenLane FOSSI dialup presentation