The following NGDBuild error occurs:
"ERROR:NGD:635 - Specification "OFFSET=IN <time>ps before <signal_name>" on signal "<problem_signal> (for_INT)" is not valid, because this signal is not connected directly to a pad."
The error above is associated with the following constraint:
NET "<problem_signal>*" OFFSET= IN <time>ns before <signal_name>;
NOTE: The "*" indicates that you want to include each bit in the bus on this constraint.
To avoid this error, place parentheses around the "*", as in the following example:
NET "<problem_signal>(*)" OFFSET= IN <time>ns before <signal_name>;
Both of these signal names must be associated with pads.
For more details on timing constraints, please see the Timing Constraints User Guide:http://www.xilinx.com/support/documentation/sw_manuals/xilinx12_1/ug612.pdf