hi ,
For Multiple clocks ,we have to know the edge of the clock that triggers flipflops.
Suppose if two clocks are A and B .
Then setup check is performed in the following manner:
The setup relationship is the closest distance between the launching clock edge (A) to the receiving clock edge (B) ,if closest distance is zero for some edges ,then take a non-zero closest distance.
The hold relationship is the closest distance between the launching edge (A) to the previous receiving edge (B)