Foreword to the Fourth Edition  Foreword to the Third Edition  We are pleased to have the opportunity in this Fourth Edition to correct  typographical errors in the Third Edition as well as to bring the book in  line with the recent revision of the ISO Pascal standard performed by  Working Group 2 ofISO committee lEC JTC I/SC22 since the standard  was formally approved in 1983. This revision of the ISO standard also  resolved differences between it and the American (ANSI-X3/IEEE  P770) standard.  The major changes affect the definition of  UnsignedReal,  textfiles,  the procedure Read, and complying processors.  We should note that, as this edition goes to press, a new "Extended  Pascal" standard is near final approval. Extended Pascal is intended to  address many complaints about limitations in the "classic" Pascal  language that this book describes.  Andy Mickel and Jim Miner  Minneapolis, USA  February, 1991  For nearly a decade  Pascal User Manual and Report  has served as the  standard tutorial and reference book for practicing programmers who  wanted to learn and use Pascal. During the 1970's the popularity of  Pascal grew beyond anyone's expectations and has become one of the  most important computer programming languages used throughout the  world. At that time in the United States, commercial use of Pascal often  exceeded academic interest. Today most universities use Pascal to  teach programming. Pascal is the modem alternative to PL/l or Algol  60,  and  even Fortran is  changing to take advantage of Pascal's  innovations.  In  our work with Pascal User's Group and  Pascal News,  we  witnessed the spread of Pascal implementations to every modem com- v 