**From Rexx to AS/400**. Rexx is a portable language across platforms. For a proof look at links in

**Hall of fame**. In

**Introduction**I would like to show that Rexx is an interesting high-level programming language, too. This is an original introduction. I concentrate only on features of the language Rexx which are not included, in whole, in the others programming languages: arithmetic operations, work with words, the interpret instruction, the SOURCELINE function, multiple exits, associative and sparse arrays. I explain a further wonder in third part of the article

**From Rexx to AS/400**: i. e.

**External data queue**. We can't imagine numbers with a gigantic number of digits; we can't use these numbers. Hence I included in

**Arithmetic operations**the complete explanation of the arithmetic operations in the Rexx language. It is a good idea consider in the course of a solution of a numeric task that "Rexx computes in the same way as we do". Instructions do-(iterate, leave)-end, numeric, interpret, parse, built-in functions, compound variables, recursion,