Create an enumerated type def. (Place a control on the FP, select Edit->Customize and then select "Type Def").
Right click on the control and select "Edit Items" and type in the names of all the DO's adding a channel description (e.g. "P1C2_") as prefix or postfix.
The channel descripter allow you to easily select the first bit to start (offset) and everyone will also know the function of the bit rightaway.