Open Watcom FORTRAN 77 Language Reference

Preface
Open Watcom FORTRAN 77 is an implementation of the American National Standard programming
language FORTRAN, ANSI X3.9-1978, commonly referred to as FORTRAN 77. The language level
supported by Open Watcom FORTRAN 77 compilers includes the full language definition as well as
significant extensions to the language. Open Watcom FORTRAN 77 compilers are based upon some well
known FORTRAN language compilers, namely the University of Waterloo’s WATFOR and WATFIV-S
compilers (implementations for the International Business Machines 370 series) and the WATFOR-11
compiler (an implementation for the Digital Equipment PDP11).
This manual describes the language level supported by Open Watcom FORTRAN 77 including extensions
to the standard language. Shaded areas in the book denote a Open Watcom FORTRAN 77 language
extension. Occasionally, where an entire section or chapter deals with a language extension, the text may
not be shaded. Users should note that extensions which are supported by this compiler may not be
supported by other compilers. We leave the choice to use a particular extension to the discretion of the
programmer.
An accompanying manual, the User’s Guide, contains system specific topics such as how to run the
software on your system, file system support, compiler options, etc.
Acknowledgements
This book was produced with the Open Watcom GML electronic publishing system, a software tool
developed by WATCOM. In this system, writers use an ASCII text editor to create source files containing
text annotated with tags. These tags label the structural elements of the document, such as chapters,
sections, paragraphs, and lists. The Open Watcom GML software, which runs on a variety of operating
systems, interprets the tags to format the text into a form such as you see here. Writers can produce output
for a variety of printers, including laser printers, using separately specified layout directives for such things
as font selection, column width and height, number of columns, etc. The result is type-set quality copy
containing integrated text and graphics.
Much of the information contained in this document was taken from the ANSI publication "American
National Standard Programming Language FORTRAN, ANSI X3.9-1978". We recommend that anyone
who is interested in the definitive description of FORTRAN 77 obtain a copy of this document. Their
address is: American National Standards Institute, Inc., 1430 Broadway, New York, New York, U.S.A.
10018.
July, 1997.
iii