A version-compatible data processing system including an application program for user interaction with stored data, the application program including means for generating, storing, and retrieving data files that each have an array of the data objects, the means for retrieving including means for determining recognition of the object type of each object, and means for retrieving each unrecognized object without processing. The application program also includes means for processing each recognized object, and means for indicating unrecognized objects, the means for storing also having means for storing unrecognized objects without modification, whereby data files generated and stored by a later version of the application program are processable and restorable as partially processed files by an earlier version of the application program in which not all object types generated by the later version of the program are recognized, the unrecognized objects being subsequently processable upon retrieval of the partially processed files by the later version of the application program.