Once created, you can query a construction line (xline) to determine the points used to create the object.
The BasePoint property can be used to obtain the first point of the xline. While the second point used to create the xline is not stored with the object, you can use the DirectionVector property to obtain the directional vector for the xline.
Dim BPoint As Variant Dim Vector As Variant BPoint = xlineObj.BasePoint Vector = xlineObj.DirectionVector