Physically exclusive clocks are clocks defined at the same source point and propagated along the same clock tree. The following figure shows an example with two primary clocks defined on the same input port.
Figure 1. Example of a Design with Physically Exclusive Clocks
Although overlap allows timing multiple application modes in one design and constraint database, avoid timing these clocks and their children generated clocks together. The Timing Constraints wizard identifies them and recommends a clock groups constraint to prevent unnecessary clock domain crossing analysis, as shown in the following figure.
Figure 2. Example of a Design with Clock Groups Constraint
