To create Fortran source programs, you can use any of the available text editors, such as vi or emacs. Source programs must have a suffix of .f unless the fsuffix attribute in the configuration file specifies a different suffix or the -qsuffix compiler option is used. You can also use a suffix of .F if the program contains cpp directives that must be processed before compilation begins.
For the Fortran source program to be a valid program, it must conform to the language definition that is specified in the XL Fortran for AIX Language Reference.