Related to checking if it is not solvable #222

I have some factors and variables that are not solvable with :parametric, but solvable with :default.
I want to use a common fg and distinguish between them using solvable.
Since > is used I can not have a factor that only works on one, eg:
:f1p -> only used with parametric
:f1d -> only used with default

We can consider moving solvable to solverdata, but then its only applicable to variables.
Again, why is it important to have > used?
What was the intended use case of Int apposed to bool, am I using it wrong?