The Wikipedia article on Rexx seems to be pretty informative: https://en.wikipedia.org/wiki/Rexx https://en.wikipedia.org/wiki/Rexx > Rexx (Restructured Extend

The Wikipedia article on Rexx seems to be pretty informative: https://en.wikipedia.org/wiki/Rexx https://en.wikipedia.org/wiki/Rexx > Rexx (Restructured Extended Executor) is a programming language that can be interpreted or compiled. It was developed at IBM by Mike Cowlishaw.[2][3] It is a structured, high-level programming language designed for ease of learning and reading. Proprietary and open source Rexx interpreters exist for a wide range of computing platforms; compilers exist for IBM mainframe computers.[4] > > Rexx is a full language that can be used as a scripting, macro language, and application development language. It is often used for processing data and text and generating reports; these similarities with Perl mean that Rexx works well in Common Gateway Interface (CGI) programming and it is indeed used for this purpose. Rexx is the primary scripting language in some operating systems, e.g. OS/2, MVS, VM, AmigaOS, and is also used as an internal macro language in some other software, such as SPF/PC, KEDIT, THE and the ZOC terminal emulator. Additionally, the Rexx language can be used for scripting and macros in any program that uses Windows Scripting Host ActiveX scripting engines languages (e.g. VBScript and JScript) if one of the Rexx engines is installed. The page goes on to discuss ARexx (the Amiga port) and Compound variables, which can be used as arrays (both of these things have been mentioned here by other commenters).