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The GNU Fortran Language
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   GNU Fortran supports a variety of extensions to, and dialects of,
the Fortran language.  Its primary base is the ANSI FORTRAN 77
standard, currently available on the network at
`http://www.fortran.com/fortran/F77_std/rjcnf0001.html' or as
monolithic text at
`http://www.fortran.com/fortran/F77_std/f77_std.html'.  It offers some
extensions that are popular among users of UNIX `f77' and `f2c'
compilers, some that are popular among users of other compilers (such
as Digital products), some that are popular among users of the newer
Fortran 90 standard, and some that are introduced by GNU Fortran.

   (If you need a text on Fortran, a few freely available electronic
references have pointers from `http://www.fortran.com/fortran/Books/'.
There is a `cooperative net project', `User Notes on Fortran
Programming' at `ftp://vms.huji.ac.il/fortran/' and mirrors elsewhere;
some of this material might not apply specifically to `g77'.)

   Part of what defines a particular implementation of a Fortran
system, such as `g77', is the particular characteristics of how it
supports types, constants, and so on.  Much of this is left up to the
implementation by the various Fortran standards and accepted practice
in the industry.

   The GNU Fortran *language* is described below.  Much of the material
is organized along the same lines as the ANSI FORTRAN 77 standard
itself.

   Note: Other Dialects, for information on features `g77' supports
that are not part of the GNU Fortran language.

   *Note*: This portion of the documentation definitely needs a lot of
work!

Relationship to the ANSI FORTRAN 77 standard:

Direction of Language Development

Where GNU Fortran is headed.

Standard Support

Degree of support for the standard.

Extensions to the ANSI FORTRAN 77 standard:

Conformance

Notation Used

Terms and Concepts

Characters Lines Sequence

Data Types and Constants

Expressions

Specification Statements

Control Statements

Functions and Subroutines

Scope and Classes of Names

I/O

Fortran 90 Features