Ordinate dimensions correspond to X-Datum or Y-Datum point coordinates. This type of dimensioning is useful, not only for elevations, but also for perforated plates or other areas with a reference point. Before applying ordinate dimensions, it is often necessary to specify a new coordinate system just for indicating a new origin.
CCS command (also
UCS, on the CCS toolbar, or Tools | New CCS main menu) creates custom coordinate systems. By default, the command prompts for the new origin, a second point that indicates X direction and a third point that indicates the positive XY plane. If Enter is pressed when prompted ...