DIFV_F_REF
if (v->dtdv_flags & ~(DIFV_F_REF | DIFV_F_MOD)) {
v->dtdv_flags & ~(DIFV_F_REF | DIFV_F_MOD));
if (v->dtdv_flags & DIFV_F_REF)
dvp->dtdv_flags |= DIFV_F_REF;
if (v->dtdv_flags & ~(DIFV_F_REF | DIFV_F_MOD)) {
v->dtdv_flags & ~(DIFV_F_REF | DIFV_F_MOD));
if (v->dtdv_flags & DIFV_F_REF)