from
The Free On-line Dictionary of Computing (8 July 2008)
OpenStep
<operating system> An {object-oriented} {application
programming interface} (API) derived from {NEXTSTEP} and
proposed as an {open standard} by {NeXT} in 1994.
OpenStep is the specification of the object kits of NEXTSTEP.
OPENSTEP/Mach was an implementation of this specification.
The original, OPENSTEP version 4.0, and really was NEXTSTEP 4.
{Rhapsody} was the codename for {Apple}'s {Mac OS X} Server,
which is really NEXTSTEP 5 (it calls itself "kernel 5.3" at
boot time).
OpenStep was designed to be implemented independently of the
computer's operating system, hardware, and user interface.
The {API} for {Rhapsody} will be a superset of {OpenStep}'s.
When the OpenStep {API} is implemented for a specific platform
and made into a product, it is written in uppercase,
e.g. OPENSTEP Developer 4.2 for Mach, or OPENSTEP Enterprise
for {Windows NT} and {Windows 95}. Versions of OPENSTEP exist
for Windows 95/NT, Solaris, HP/UX, and Mach.
(1999-11-25)