Example 2-14. Enum Names Example
enum PinStateType { PIN_OFF, PIN_ON, };
It's often useful to be able to say an enum is not in any of its valid states. Make a label for an uninitialized or error state. Make it the first label if possible.
Example 2-15. Invalid Enum States Example
enum { STATE_NONE, STATE_OPEN, STATE_RUNNING, STATE_DYING};