This is a secondary option for controlling the degree to which the fitter flattens a design netlist. A logic gate can collapse forward into a subsequent gate only if the number of inputs in the resulting logic function does not exceed the input limit. If the design fails to fit the target device because flattening uses up too many of the function block inputs, decrease the input limit to prevent flattening of certain high fan-in functions. Choose a number from 2 to 36 for XC9500, and from 2 to 54 for XC9500XL and XC9500XV. The default is 36 for XC9500, and 54 for XC9500XL and XC9500XV.