For data sets, you can specify a default management class in an SCDS. DFSMShsm applies the default management class to all system-managed data sets that do not already have a management class. Unlike the data sets that you have already assigned a management class, the catalog entries of these data sets do not contain a management class name. For objects, the default management class is defined in the catalog entry for the object collection to which the objects belong. The default management class is assigned by the management class ACS routine when the first object is stored in the collection.