function FuncName(NormalizedFloat accuracy)

In languages with operator overloading you can make NormalizedFloat a proper class with asserts in debug version and change it to an alias of float in release version.

Similarly I wonder why gemoetry libraries don't define separate Point class and Vector class, they almost always use Vector class for vectors and points.

I understand math checks out, and sometimes you want to add or multiply points, for example:

    Pmid = (P0 + P1) / 2
    

But you could cast in such instances:

    Pmid = (P0 + (Vector)P1)/ 2

And the distinction would surely catch some errors.

    Point - Point = Vector
    Point + Point = ERROR
    Vector +/- Vector = Vector
    Point +/- Vector = Point
    Point * scalar = ERROR
    Vector * scalar = Vector
    Point */x Point = ERROR
    Vector * Vector = scalar
    Vector x Vector = Vector

UnitInterval seems to contains an interval, not a single float. I don't think it's a very good name.

UnitIntervalNumber would be better, but it's too long. Something like UnitNumber or UnitFloat could maybe work.

After reading this reply twice, I realised you are right and UnitInterval type indicates an interval object instead of a single scalar number.

I have actually used intervals, and should have realised this sooner. But I just had my first cup of coffee...

Yes, UnitInterval is a really bad name for a single number. Astonishingly, it has 30 upvotes on SO.