An object-oriented programming interface (API) from Apple, which enabled the NeXTSTEP environment to run on Sun's Solaris, Windows NT and NeXT's OPENSTEP (all caps in the name) operating system. Originally developed by NeXT Computer, the OPENSTEP OS became Rhapsody and then Mac OS X, and the OpenStep API became the Yellow Box (Cocoa) programming interface. See
NeXT,
NeXTSTEP,
Rhapsody and
Cocoa.