A model for this must provide:

template <class ForwardIterator>
Orientation fo ( ForwardIterator first , ForwardIterator last )
determines the orientation of the points of the tuple A = tuple [first,last) where A consists of d + 1 points in d-space. This is the sign of the determinant
1 1 1 1
A[0] A[1] A[d]
where A[i] denotes the Cartesian coordinate vector of the i-th point in A.
Precondition: size [first,last) == d+1 and A[i].dimension() == d 0 i d.
Requirement: The value type of ForwardIterator is Kernel::Point_d.