Apple named its upcoming NeXT-based system Rhapsody, while it continued to improve the existing Mac OS, often with technology that was supposed to go into Copland. Rhapsody saw two developer releases, in September, 1997, and May, 1998. Jobs became the interim CEO of Apple on September 16, 1997. Mac OS X was first mentioned in Apple's OS strategy announcement at the 1998 WWDC. Jobs said that OS X would ship in the fall of 1999, and would inherit from both Mac OS and Rhapsody. Moreover, backward compatibility would be maintained to ease customers into the transition.
