For manual CMMs:

When creating a point in the center of a measured (by probe, 4-points) open slot, what determines the position of the point on the parallel axis of that slot? 

By definition that point could be anywhere on that slot's parallel axis, but it looks as if CMM-Manager is assuming the slot has some length and placing the point at the center of that length.

For finding the center of the open slot pattern relative to the alignment datum (center of the part) this would present an issue as the pattern would be subject to the assumed length of each open slot.

Thanks in advance.