.file tells as that we are about to start a new logical file. string is the new file name. In general, the filename is recognized whether or not it is surrounded by quotes "; but if you wish to specify an empty file name, you must give the quotes-"". This statement may go away in future: it is only recognized to be compatible with old as programs. In some configurations of as, .file has already been removed to avoid conflicts with other assemblers. Chapter 9 Machine Dependent Features.