Kilowatt Software L.L.C.
Classic Rexx Tutorial
Language Level 4.00 (TRL-2)


This is an introductory tutorial to the Rexx programming language.

Rexx provides exceptional capabilities for processing character text strings. All program values are strings. Some string values can be processed in arithmetic operations. String values can contain arbitrary byte values including binary zeroes.

The powerful parse instruction provides many ways for extracting string segments to variables.

Rexx programs are usually processed immediately by an interpreter, rather than a compile/link/execute sequence.

Rexx is very helpful for developing small programs that perform various text file transformations.

Here are helpful indexes of Rexx language instructions, function, and a syntax summary.

The following links are organized to introduce concepts for new Rexx programmers. Proceed down the columns and then to the right. Advanced programmers can reference a specific link, as necessary.

Hint: you can use the Tab key to sequence through the links.


This tutorial describes classic features of the Rexx language. The intent of the tutorial is to enable you to become a proficient Rexx program developer, without any initial expense.

The tutorial is not a document of a specific Rexx implementation. Many implementation-specific considerations are highlighted within the tutorial.

Rexx is a programming language that was developed over a ten year period, with extensive personal effort by IBM's Michael Cowlishaw. Click here to review the background history of the Rexx language.

The tutorial is a condensation of details that are documented in Michael Cowlishaw's famous book:

The Rexx language, as documented in TRL-2, has numerous syntactic and semantic intricacies and nuances which are beyond the scope of this tutorial. You should obtain the above book if you plan to be an expert Rexx program developer.

The TRL-2 book can be obtained at one of the following internet sites:

TRL-2 was the basis of the American National Standards Institute's effort to standardize the definition of the REXX language. This standardization effort was identified as the ANSI X3J18 project. The American National Standard (ANSI Standard) for Rexx is called "Programming Language - REXX", and its number is X3.274-1996. Click here to learn about the ANSI REXX standardization project.

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Last updated on: 18 Oct 2015