Restructured EXtended eXecutor language. A command procedure cum programming language which was initially available on z/VM only, replacing EXEC and EXEC2, but later became an SAA standard. Although SAA is a distant memory, REXX availability in z/OS TSO has seen it replace CLIST as the tool of choice, especially given the fact that TSO, and therefore REXX, can be run in batch. REXX is an effective programming language in its own right with powerful string processing facilities and is used to drive certain program products, notably GDDM. REXX is also available in VSE/ESA, AIX OS/2, Linux and Windows. Although normally interpretive, a REXX compiler and library is available for z/OS and z/VM. REXX for CICS is available for z/OS and VSE/ESA; it consists of REXX Development System and REXX Development System. Object REXX is available for Windows, OS/2, AIX, and Linux for Intel and zSeries 900. See also REXX Language Support.