Abstract: In a telephone switching system, a method of performing a multiple release jump to a target program release for controlling the system. The system uses duplicate processors and disk file controllers. A new disk file is initialized with new program text and a target release version of office dependent data. This target release version is derived by upgrading the office dependent data one release at a time until office dependent data for the target release is derived. The new program text and target release version of office dependent data is inserted into one member of a duplicate disk file controller system which may either be a new disk file controller or one of the two disk file controllers currently in use in the system.