Fortran mode is meant for editing “fixed form” (and also “tab
format”) source code (normally Fortran 77). For editing more modern
“free form” source code (Fortran 90, 95, 2003), use F90 mode
f90-mode). Emacs normally uses Fortran mode for files with
extension ‘.f’, ‘.F’ or ‘.for’, and F90 mode for the
extensions ‘.f90’ and ‘.f95’. Customize
auto-mode-alist to add more extensions. GNU Fortran supports
both free and fixed form. This manual mainly documents Fortran mode,
but the corresponding F90 mode features are mentioned when revelant.
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. Fortran mode also supports Hideshow minor mode (see Hideshow), and Imenu (see Imenu).
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