When running timing analysis, the user gets the following: FATAL_ERROR:Timing:bastwprcntl.c:1922:1.27 - There
is no PERIOD constraint for the OFFSET constraint
TIMEGRP "OPADS" OFFSET = OUT 25 nS BEFORE
COMP "CLK" ; . Process will terminate.
Also See (Xilinx Solution 5489)
This should not be a fatal error, but to get around this, please
add a PERIOD constraint to the design.
This issue will be addressed in a future release.