NCHG
np->n_flag &= ~(NWRITEERR | NACC | NUPD | NCHG | NLOCKED | NWANTED);
if (np->n_flag & NCHG) {
if (np->n_flag & NCHG) {
np->n_flag |= NCHG;
np->n_flag |= NCHG;
if (flag & NCHG)