Abstract: The present invention provides a computer system for providing data compatibility between different versions of a computer program. The computer system comprises a memory which stores a later version of a computer program and a prior version of the computer program. A user of the computer system invokes the prior version of the computer program, creates a file, and requests that the file be saved on a permanent storage device. The computer system of the present invention automatically saves the file in both a version dependent external format and a version independent data format. When the user of the computer system invokes the later version of the computer program and requests to process the data stored in the file, the computer system determines whether the data stored in the version dependent external format can be processed by the later version of the computer program.