/SOURCE_FORM=option D=Depends on file type

 /SOURCE_FORM

 Specifies whether all VSI Fortran source files on the F90
 command line are in fixed or free source form.

 FIXED
   Specifies that the input source files will be in fixed source
   form, regardless of the file type.  Source files with a file type
   of FOR or F (or any file type other than F90) are assumed to
   contain fixed source form.

 FREE
   Specifies that the input source files will be in free source
   form, regardless of the file type.  Source files with a file type
   of F90 are assumed to contain free source form.