dn_membid
assert(dnp->dn_membid < dxp->dx_nmembers);
BT_SET(pcb->pcb_asxrefs[dxp->dx_id], dnp->dn_membid);
assert(dxp->dx_membdif[mnp->dn_membid] == NULL);
dxp->dx_membdif[mnp->dn_membid] = dt_as(yypcb);
ddo->ddo_pgp->dp_xrefs[dxp->dx_id], dnp->dn_membid);
dxp->dx_membdif[dnp->dn_membid]);
dnp->dn_membid = dxp->dx_nmembers++;