PCB Layout CAD : DRC/MRC Settings
The Reference settings enable you to specify target layers for verifying the number of references of components/footprints with MRC: Reference.
Enables to specify target layers for verifying the number of references of components/footprints. Those layers can be selected from the pull-down menu. A MRC error will occur when the number of references for each component/footprint that has been placed on the target layers is "0" or "2 or more". The check boxes next to the entry fields allow you to toggle the verification on and off.