Gets or sets the name of the column that contains the primary key for each map feature on the DWG layer.
If this property is modified successfully, it automatically sets the layer's rebuild flag to True. See Rebuild for details.
Note that for write operations, this property does not work during a busy state. For additional information, refer to "Handling Busy State and Map Refresh" chapter in the Autodesk MapGuide Developer's Guide.
-1 (busy): For write operations only.