filter converter name is `conv_enum`. The real field python data is `string`, but we can't use `strings = (FilterEqual, FilterNotEqual, FilterLike, FilterNotLike)` cause we need only `FilterEqual, FilterNotEqual`. So I don't see a problem to call it `emun = (FilterEqual, FilterNotEqual)` (or maebe `choices` or `select_filters`). I don't think this is fundamentally issue