PREFACE The information in this book was prepared so that it can serve a dual purpose. The first purpose is to provide a study aid for the Control Systems Engineering Professional Engineering Exam that is presided over by the NCEES. The second purpose is to provide a technical reference for future use by the instrumentation / automation professional. Where the author cites any references to commercially available products@ it is for reference only and is by no means an endorsement by the author of any commercially available product. Sample problems presented in this book are not meant to influence the reader on specific problems that may be on the exam@ but rather to reinforce the technical material that has been presented to the reader.