MTF_EXISTS
sc->sc_flags = MTF_EXISTS;
if ((sc->sc_flags & MTF_EXISTS) == 0)
sc->sc_flags &= MTF_EXISTS | MTF_OPEN | MTF_REW;
sc->sc_flags &= MTF_OPEN | MTF_EXISTS;
sc->sc_flags = MTF_EXISTS;
if (sc == NULL || (sc->sc_flags & MTF_EXISTS) == 0)
sc->sc_flags &= MTF_EXISTS | MTF_OPEN | MTF_REW;
sc->sc_flags &= MTF_OPEN | MTF_EXISTS;