Query Objects in Layers
When you import or link a file to a Revit project, you can query the file for information about its objects.
Hide Layers in CAD Files
When you hide layers in an imported file or a linked file, the layers are still available to the Revit project, but they do not display in views.
Delete Layers in CAD Files
When you delete layers in an imported file or a linked file, the layers are no longer available to the Revit project. However, they still exist in the original CAD file.
Control Graphic Overrides for Linked Files
When you change the graphic display of layers in a linked file, you can specify whether Revit preserves or discards the graphic overrides.