I am unable to create a NET TIG constraint on the same net for more than one TSid.
TIMESPEC "TS_1" = FROM "FFS" TO "FFS" 20 ns;
TIMESPEC "TS_2" = FROM "FFS" TO "PADS" "TS_1" / 1.1;
NET clk TIG TS_1;
Constraints Editor does not allow me to create NET clk TIG TS_2; instead, it replaces the above constraint.
To work around this problem, manually manipulate the UCF to create the desired constraint.
This will be fixed in the next major software release (after 5.1i).