DV_DSF_12
(dv->payload[0] & DV_DSF_12) == 0)
dv->payload[0] |= DV_DSF_12;
(dv->payload[0] & DV_DSF_12) == 0)
dv->payload[0] |= DV_DSF_12;
system = ((dv->payload[0] & DV_DSF_12) != 0);