Source Form Assumed

The source form assumed by f90 depends on options, directives, and suffixes.

Table C-1 F90 Source Form Command-line options

Option	Action
-fixed	Interpret all source files as Fortran fixed form
-free	Interpret all source files as Fortran free form

If the -free or -fixed option is used, that overrides the file name suffix.

Table C-2 F90 File name suffixes

Suffix	Source Form
.f90	Fortran free-form source files
.f	Fortran fixed-form source files or ANSI standard FORTRAN 77 source files
.for	Same as .f.
.ftn	Same as .f.
other	None--file name is passed to the linker

If either a FREE or FIXED directive is used, that overrides the option and file name suffix.

Mixing Forms

Some mixing of source forms is allowed.

• In the same f90 command, some source files can be fixed form, some free.

• In the same file, free form can be mixed with fixed form by using directives.

• In the same program unit, tab form can be mixed with free or fixed form.

Case

Sun Fortran 90 is case insensitive. That means that a variable AbcDeF is treated as if it were spelled abcdef, or abcdeF, etc. "Compatibility with FORTRAN 77"