From the HPE menu bar, select DES | Add DES... or from the toolbar, click
on the Add DES button . This will open the dialog box
shown below.
Use the first radio button to select whether the DES will be added to the High level, Interface or Low level. Use the drop down box to select whether the DES will be part of a Subsystem or Interface. Use the second radio button to select whether the DES will be of type Plant or Supervisor. In the text box, type the name of your new DES, or click Browse, to open an existing DES.