Melbourne air traffic control received co-ordination details on Air New Zealand Flight NZ114 from Perth air traffic control. This indicated the route shown on the flight progress strips held in Melbourne was different to tracking details co-ordinated from Perth. It was discovered that the Computer Aided Strip Printing System (CASPS), which automatically prints flight progress strips from the flight plan had made an error. This was partly due to a complicated route description in the plan message and a software error in the CASPS system. The strips should have been checked by the flight data officer against the flight plan. The error was not detected by the flight data officer.