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.