Logically exclusive clocks are clocks that are defined on different source points but
share part of their clock tree due to a multiplexer or other combinational logic. The
Timing Constraints wizard identifies such clocks and recommends a clock groups
constraint directly on them when they do not have timing paths between each other except
for the logic connected to their shared clock tree. The following figure shows an
example of two clocks, clkA and clkB, which are
defined on different input ports and start overlapping on the output of a BUFGMUX.
Figure 1. Example of Logically Exclusive Clocks with No Interaction
