You must specify a coordinate system for each attached source drawing to take advantage of coordinate transformation capabilities.
To assign a coordinate system to a source drawing
If you do not know the code, click Select Coordinate System. In the Select Global Coordinate System dialog box, select a category. Select from a list of available coordinate systems. You can also search for coordinate systems by code or description using the Search box. Click Properties to view the properties of the selected coordinate system.
To remove an assigned coordinate system, in the Code box in the Assign Global Coordinate System dialog box, type a period.