This valuable technical reference guide also serves as an excellent text for familiarizing oneself with IBM’s IMS/VS data communications (DC) programming environment. The book focuses on the use of Message Format Service (MFS), a software development tool that facilitates IMS/VS DC programming. The book is divided into three sections. The first section includes IMS/VS concepts and terminology, components of MFS, transaction flow in database and data communications environments, and IBM’s IMS DL/1 calls for terminal input/output. The second section focuses on MFS facilities and programming techniques; the author presents COBOL examples using MFS. The third section deals with advanced IMS/VS DC functions such as conversational processing, batch messaging, and checkpoint/restart facilities. This book requires an understanding of programming in an IBM large-scale systems environment but, given that knowledge, it is an extremely well-done volume with excellent and plentiful examples. It is well organized and clear, and it should be useful to the large-scale IBM IMS database or DC COBOL programmer in the early stages of his or her career.