Determine if the created geometry is referred to other objects or is free
By default, the geometry model is independent but it can be created as referenced to other objects. This means that a new object can be created by its underlying entities already defined. These underlying entities may be modified and as well the new dependent object.
For example, a triangle is referenced to existing three points: point A, point B and point C, already defined beforehand with their point coordinates. If coordinates of any point are modified the resulting referenced triangle surface will be updated (triangle may be converted into a ruled surface if any of the new points is not in the same plane). If the triangle was created as a non referenced object it must be created by introducing new points and its location cannot be modified afterwards.
When a point is created as referenced then its coordinates are not referred to the origin of active coordinate but to a reference point previously created.
