New AS/400 programmers will find this text a systematic approach to data description specifications concepts and the foundation needed to take on complex tasks. Experienced programmers will find it a handy reference to DOS functions they are already using and also an efficient guide to very advanced applications. Extensive real-life examples of sophisticated DDS programming for CL and for RPG are included, which means that solutions for many applications can be taken straight out of the book. This is updated to include V4RI and V4R2 changes or additions to DOS.