V5R

V5R, short for Version 5 Release, is a historical naming convention used by IBM to designate a generation of its midrange operating system family, originally known as OS/400 and later as IBM i. In this scheme, Version 5 identifies the major version of the operating system, while Release specifies a maintenance level within that version. The V5R family comprises several releases, commonly referred to as V5R1 through V5R4, which correspond to the OS/400 era’s fifth version and its successive maintenance packs. These releases were part of the transition from the OS/400 lineage to the IBM i platform on POWER hardware, and they encompassed incremental improvements in system performance, security, database capabilities (DB2 for i), and developer tools, along with expanded support for web and modern programming interfaces.

In practical terms, software written for IBM i on OS/400 could often continue to operate across V5R releases, subject to compatibility constraints typical of IBM i. The V5R naming eventually gave way to newer versioning as IBM introduced the IBM i 6.x series and beyond, with subsequent releases continuing the Version, Release, and Modification (VRM) convention adapted to newer branding. Today, V5R is primarily of historical interest, referenced mainly in archival documentation, migration guides, and by systems still running older IBM i installations. See also IBM i, OS/400, and DB2 for i.