Multiplicity letter codes for large amount of states

Well, let's say we have a large amount of states computed (e.g. over 50), all with the same multiplicity.


So, our ground state can be $X^2\Sigma^+\_g$ and we can continue with $B^2, C^2$ etc. as described in [Molecular orbitals symmetry - states notation](https://chemistry.stackexchange.com/questions/104472/molecular-orbitals-symmetry-states-notation) and [Letter codes in molecular term symbols](https://chemistry.stackexchange.com/questions/59211/letter-codes-in-molecular-term-symbols).


But what is the convention of the number of states is larger, than the number of letters? Does any convention like $B^2\_2$ exist?


