10. A data processing system as set forth in claim 1, wherein said means for selecting a natural language is responsive to a command by a user to invoke an application program using a desired interaction language for setting the current interaction language to the desired interaction language if a message file containing messages in the desired interaction language is available and for setting the current interaction language to a default interaction language if the desired interaction language is not available.
10. A data processing system as set forth in claim 1, wherein said means for selecting a natural language is responsive to a command by a user to invoke an application program using a desired interaction language for setting the current interaction language to the desired interaction language if a message file containing messages in the desired interaction language is available and for setting the current interaction language to a default interaction language if the desired interaction language is not available. 11. A data processing system as set forth in claim 10, wherein the processor is controlled by an operating system which operates in response to instructions in the application program, and further including: means for loading the message file for the selected natural language for the invoked application program into the memory; and in the operating system, means for establishing a link in the link table responsive to the means for loading a message file.