NAME
        TD_PROTSTATUS -- return whether the current disk is write-protected.

   FUNCTION
        This command is used to determine whether the current disk is
        write-protected.

   IO REQUEST INPUT
        io_Device       preset by the call to opendevice()
        io_Unit         preset by the call to opendevice()
        io_Command      TD_PROTSTATUS
        io_Flags        0 or IOF_QUICK

   IO REQUEST RESULT
        io_Error - 0 for success, or an error code as defined in
                   <devices/trackdisk.h>
        io_Actual - if io_Error is 0, this tells you whether the disk in the
                    drive is write-protected. 0 means the disk is NOT write-
                    protected, while any other value indicates it is.