Fortran mode provides special motion commands for Fortran statements and subprograms, and indentation commands that understand Fortran conventions of nesting, line numbers and continuation statements. Fortran mode has support for Auto Fill mode that breaks long lines into proper Fortran continuation lines.
Special commands for comments are provided because Fortran comments are unlike those of other languages. Built-in abbrevs optionally save typing when you insert Fortran keywords.
Use M-x fortran-mode to switch to this major mode. This command
runs the hook fortran-mode-hook (see Hooks).
Fortran mode is meant for editing Fortran77 “fixed format” (and also
“tab format”) source code. For editing the modern Fortran90 or
Fortran95 “free format” source code, use F90 mode (f90-mode).
Emacs normally uses Fortran mode for files with extension ‘.f’,
‘.F’ or ‘.for’, and F90 mode for the extension ‘.f90’ and
‘.f95’. GNU Fortran supports both kinds of format.