Today I use the simple UML diagram for delineating the working sequence of transformation. Map 3D is able to transform an existing map from one coordinate system to another by querying the objects from the attached source drawing into the current drawing. The original drawing is unchanged, but the objects in the current drawing use the new coordinate system. Once the objects are in the new drawing, you can detach the source drawing and save the new drawing. The objects are unchanged in the source drawing, but they use the new coordinate system in the new drawing.

Geodetic Datum Transformation and Map Projection Parameters (Lands Department) - pdf
Datum Transfomation (Marine Department) - url