Customizing enumerations

How do you handle enumerations with no default value - you only want to see "--" in the plan view?

You can achieve this by selecting none for Default Literal in Project Customization-->Configuration Data-->Work Items-->Enumerations, and it is possible to save the process template with "None" as the value for default literal - despite the fact that an error sign is displayed.

But is this the right way to do it?

Peter