Meaning – The term OpenEdition, refers to the elements of OS/390 that incorporate the UNIX interfaces standardized in POSIX.

UNIX System Services allows UNIX applications from other platforms to run on IBM System z mainframes running z/OS. In many cases, only a recompile is necessary, although additional effort may be advisable for z/OS integration (such as SMP/E installation support). While z/OS UNIX supports ASCII and Unicode, and there’s no technical requirement to modify ASCII and Unicode UNIX applications, many z/OS users often prefer EBCDIC support in their applications including those running in z/OS UNIX.

The file systems for z/OS UNIX (the older HFS and the now preferred zFS), which support UNIX-style long filenames, appear as special VSAM datasets to the rest of z/OS. Numerous core z/OS subsystems and applications rely on UNIX System Services, including the z/OS Management Facility, XML parsing, and generation services, OpenSSH, the IBM HTTP Server for z/OS, the z/OS SDK for Java, and some z/OS PKI services as examples.

Example of usage“z/OS UNIX’s predecessor was an operating system component called OpenEdition MVS, first implemented in MVS/ESA 4.3 and enhanced in MVS/ESA 5.1. OpenEdition MVS only supported the POSIX standards.”