This updated, classic work on the RPG language covers all the new functions and features that have been added since 2003, including new op codes and built-in functions, new chapters on free-format RPG IV and Web programming interfaces, information on implementing XML within RPG IV, and expanded information on procedures. This reference guide takes both novice and experienced RPG IV programmers through the language, from its foundation to its most advanced techniques. More than 100 charts and tables, as well as 350 real-life code samples of functions and operations are included, showing readers how the rules apply in an easy-to-follow format.