RD_MSGNODIS
(stp->sd_read_opt & (RD_MSGDIS|RD_MSGNODIS))) {
stp->sd_read_opt &= ~(RD_MSGDIS | RD_MSGNODIS);
((stp->sd_read_opt & ~RD_MSGNODIS) |
RD_MSGNODIS);
stp->sd_read_opt &= ~(RD_MSGDIS | RD_MSGNODIS);
stp->sd_read_opt = (stp->sd_read_opt & ~RD_MSGNODIS) |
RD_MSGNODIS;
((stp->sd_read_opt & RD_MSGNODIS) ? RMSGN : RNORM));