How to Model data using UML for this situation?

The Situtation is that there is a data named Progress which has 2 valid values (suppose 'A' and B). this means Progress = 'A' or Progress = B. A is just a string, but B is not string. B itself has some valid values (suppose strings: 'V1', 'V2', 'V3'). progress can be A which is a string or can be B which is 'V1', 'V2' or 'V3'. How to model this data?image

If B is just a simple string (just like A) so we can define Progress as a string but i think one solution is defining progress as a class which has two children: Class A & Class B. Class B has 2 fields: Id & state so we have 3 IDs which correspond to 3 states: 'V1', 'V2' and 'V3' and Class A with a const field called state with fixed value 'A'. so with this solution progress can be objects A or B which has a state.

Please help me if such design is not good or if there is any design pattern for such situation.