Returns a comma-separated list of names of all the members of the enum type. The method
        returns an error if invoked on a type that is not an enumeration.
      
        Return type: CHARACTER
      
        Access: PUBLIC
      
        Applies to:
        Progress.Lang.Class class
     
    
    Notes
- The list of names returned is in order of ascending numerical values, regardless of whether the
          values were explicitly set. For flag enum types, the members with positive numeric values
          are listed in ascending order first, and then the members with negative numeric values are
          listed next, also in ascending order.
 
        - If two or more members are defined with the same numeric value, there is no guarantee
          for the order in which they are returned.