Issue link: https://resources.pcb.cadence.com/i/1532922
However, that will only cause the members of that Net Class to be distanced 60 mils away from other nets outside of the class of differential pairs. While that's desirable, we want the differential pairs to only need to be 20 mils apart or more amongst themselves. Otherwise, if differential pairs had to be 60 mils away from other diff pairs, it would be near impossible to route differential pairs on a dense PCB. They would be forced to stay 60 mils away from each other, which is not necessary in many cases. Class-to-Class Spacing for Differential Pairs to Differential Pairs Spacing So, for this reason, Class-to-Class spacing is introduced, so that any CLS1_DIFF class object can be 20 mils from any other CLS1_DIFF class object (one differential pair to another). To implement said class-to-class spacing, click the Net Class-Class > All Layers worksheet. Right-click the Cadence_Demo design, choose Create – Class-Class. 60 www.cadence.com OrCAD X Constraint Management Guide