The Data Modeler is linked to version management, that is, versions are stored for each modeling object. An object can have a number of different versions. These are distinguished by an object status entry and a version number.
A detailed description of version management can be found in the documentation for the ABAP/4 Dictionary.
Please note that definitions cannot have more than one version and that previous versions cannot, therefore, be retrieved.
Before reloading a stored version, check whether the modeling object being retrieved fits the context of the existing relationships, specializations, and table/view assignments.