HELP SYSFILEMODE                            Mark Rubinstein  January 1986

    sysfilemode(<filename>) -> integer;
    integer -> sysfilemode(<filename>);

This procedure, and its updater, accesses or changes the mode flags
(protection) of a file.  Unix file modes are best understood in octal
(base 8) form and are best illustrated by using the unix command 'ls -l'.
If a file is readable and writeable by the owner and only readable by
other users then 'ls' will print this as '-rw-rw-r--'.  Its octal form is
8:664 which is the default setting for *POP_FILE_MODE.

For example:

    8 -> pop_pr_radix;              ;;; print numbers to base 8
    sysfilemode('init.p') =>
    ** 100664                       ;;; the 'top' numbers are to do with if
                                    ;;; the file is a directory.
    8:444 -> sysfilemode('init.p'); ;;; make the file 'read only'
    sysfilemode('init.p') =>
    ** 100444                       ;;; mode changed.  Top bits
                                    ;;; undisturbed.

NOTE: This facility is only available on UNIX machines.
