The number of parameters is followed by an optional list of of modifiers, starting with a letter to indicate the parameter rank and optionally swapping the case from the previous letter in case the type at this position is also higher kinded.
Examples:
[_]- 1
[_, _]- 2
[_[_], _]- 2a1
[_, _[_]]- 2b2
[_[_[_]], _]- 2a1A1
[_, _[_[_]]]- 2b1A1
[_[_, [_]], _]- 2a2B1