MBR
v = MBR; /* modified byte */
s = MBR;
DKWEDGE_DISCOVERY_METHOD_DECL(MBR, 10, dkwedge_discover_mbr);
dw |= (MBR((sp)[1], 32 - (x))); \
*(dp) = (*(dp) & ~mask) | (MBR(sw, x) & mask); \
*(dp) = (*(dp) & rasops_rmask[x]) | (MBR(sw, x)); \