In a parametric system, geometric elements can be defined with respect to each other. In some instances, the geometric context of an element in parametric space can change. This is done by changing the associative relationships of the element.

For example, a point may be defined with a coordinate system as it’s parent, using X, Y, and Z coordinates to define it’s location in space. You can switch the support of that point from the coordinate system to a line, using a t-parameter to specify its location. Switching the support of the point changes its reference from a cartesian coordinate system to a line in parametric space.