ID:13388 Verilog HDL error at <location>: range index cannot contain X or Z

CAUSE: In a Verilog Design File (.v) at the specified location, you used a Don't Care (X) or High Impedance (Z) value in defining a range. However, a range represents a number of bits, so an X or Z value is not legal for a range specification.

ACTION: Edit the design so all values in range specifications evaluate to a constant integer.