Several mechanisms were formerly used for managing versions of custom object classes used in ObjectARX applications:
For most situations, these mechanisms have been superseded by the class versioning system. If the custom class might have its data format changed within the same AutoCAD maintenance release version, then both the class versioning system and some other mechanism, such as version numbering, would need to be used. The version numbering would tell the custom class which version its data was written in and the class version system values would tell the base classes what version their data was written in. The earlier mechanisms are described below (following the description of class versioning).