In addition to the generic FME feature attributes that FME Workbench adds to all features (see About Feature Attributes), special FME feature attributes direct the FDO writer as it adds features to its output files, and are used by the FDO reader to store the characteristics of the features it reads. The most important of these is the fdo_type attribute, which controls the overall interpretation of the feature. The correct values for fdo_type are fdo_point, fdo_multipoint, fdo_curve, fdo_line, fdo_arc, fdo_multicurve, fdo_multiline, fdo_curvepolygon, fdo_polygon, fdo_ellipse, fdo_multicurvepolygon, fdo_multipolygon and fdo_null. The parameters specified for each of these are described in the following subsections: