[V8i VBA] Vector3dPolarAngle Method - Result inverse of expected, why?

Simple test case above, I have a vector and I am using Vector3dPolarAngle to access the existing rotation of the vector. My understanding is the angle returned is calculated counter-clockwise from the x-axis yet the value provided as viewed in locals window/debug.print is measured clockwise from the x-axis. Is this a bug or an accepted feature of this particular method?

Dim UnitNormal                            As Vector3d
UnitNormal = Vector3dNormalize(Vector3dSubtractPoint3dPoint3d(SourceCoordinate, ProjectedPoint))
Dim AngleRadians As Double
AngleRadians = Vector3dPolarAngle(UnitNormal)