It is important to preserve the Verilog header file sequence if your Verilog header files are interdependent.
To specify the Verilog header file order:
From the Options menu, choose Header File Organization. The Verilog Header Files dialog box appears.
Use the up and down arrows to specify the order, or drag the files into order.
Select Simulation or Synthesis if you want the file included when simulation or synthesis is run.
Click OK.