When you run a query, AutoCAD Map 3D toolset finds all the objects in the attached drawings that match the query criteria, and copies those objects to the current drawing.
Example: You have separate drawings for each quadrant of a town. You create a main drawing and attach the other drawings, and then view all water mains in the town or all emergency routes.
Tiling is one way to manage multiple DWG files.
You can save the queried objects back to their attached drawings by adding them to the save set before you edit them. When you save the current drawing, AutoCAD Map 3D toolset prompts you to save the objects in the save set back to their attached drawings. If you do not add modified objects to the save set, you can save the modifications to the current drawing or to a new drawing, but the changes are not saved back to the attached drawings.