Formal specifications are exactly the same. Some are entirely performance based. Others will preclude all but a single implementation method. And most are so

Formal specifications are exactly the same. Some are entirely performance based. Others will preclude all but a single implementation method. And most are somewhere in-between. Because specifications are written for a concrete context. The context solely determines what makes sense to write. The abstractions are only abstractions. The specifications are a legal or quasi-legal obligation.