Extended attributes are data beyond the standard location and description fields. The internal storage has been implemented to conform to MapWorks Extended Data, so you can use those tools to edit and manage, etc.
MapWorks currently reads Carlson VTT files (matching CRD files) for extended data and writes additional columns on CSV output.
MapWorks currently exports extended attributes with the ShapeFile Write tool and we recently added extended attributes to the Point Report tool. Note that since the extra columns can vary with each file, the point report tool does not store the selected columns like we do for point, elevation, etc.