RPG IV, a Modern Language

In 2001, with the release of OS/400 V5R1, RPG IV offered even greater freedom for calculations than offered by the Extended Factor-2 Calculation Specification: a free-format text-capable source entry, as an alternative to the original column-dependent source format. The "/FREE" calculation does not require the operation code to be placed in a particular column; the operation code is optional for the EVAL and CALLP operations; and syntax generally more closely resembles that of mainstream, general-purpose programming languages.

Today, RPG IV is a considerably more robust language. Editing can still be done via the simple editor or it can be edited via PC using IBM's Websphere Development Studio (a customized implementation of Eclipse). IBM is continually extending its capabilities and adding more built-in functions (BIFs). It has the ability to link to Java objects (See IBM's RPG Reference Manual [1] ), and i5/OS APIs; it can be used to write CGI programs with the help of IBM's Cgidev2[2]web toolkit, RPG xTools [3] CGILIB and other commercial Web enabled packages. Even with the changes it retains a great deal of backward compatibility, so an RPG program written 37 years ago could run today with little or no modification.

The OS/400 was later renamed i5/OS in correspondence with the new IBM System i branding initiative. The i5/OS V5R4 [4] (Version 5 Release 4) was released in January 2006 and is currently the latest version (as of August, 2007).