Specifies that the current pin is not a clock, and should not be included as a clock source during timing analysis. This assignment may be useful because the Quartus^® II software automatically identifies any pin feeding the clock input of a register, that does not have a Clock Settings timing assignment, as an undefined clock. This assignment allows you to specify that the Quartus II software should not treat the specified pin as a clock source during timing analysis. You can assign the Not a Clock assignment to any input or bidirectional pin.