What is a CAD feature class?
A CAD feature class is a read-only member of a CAD feature dataset comprising supported CAD geometry and attribution in one of the following feature class types: annotation, multipatch, point, polyline, and polygon.
The attribute table for each CAD feature class is a virtual table that exposes property values for geometry, layers, text, and user-defined attributes contained in the CAD file. The field values can be queried, used as filtering criteria for visualization tasks, and computed as feature data.
When you add a CAD feature class to ArcMap, ArcScene, or ArcGlobe, all standard map functions are enabled, including attribute tables and labeling functions. You can snap to geometry, substitute symbology, and use it with all geoprocessing tools that accept feature classes or layers as input.
CAD-defined feature classes
A CAD-defined feature class is a subset of one of the five generic feature class types. It is uniquely named and supports entity-linked attributes stored in a DWG file (AutoCAD version 2007 or higher).
Entity-linked attributes are viewable in the virtual attribute table alongside the CAD property fields. They are automatically imported to a geodatabase with the input features using any geoprocessing tool that accepts a feature class or layer as input.
Feature geometry is inherited from the default CAD feature class type and displayed in both feature classes. For example, a CAD-defined polyline feature class named Parcels displays only the polylines defined as members of the Parcels feature class, while the default Polyline CAD feature class maintains the full collection of polylines stored in the CAD file.
By default, exporting data to AutoCAD drawings generates CAD-defined feature classes.
For detailed information about how this data is structured, reference the ESRI document Mapping Specification for CAD available on the ArcGIS for AutoCAD Resource Center.