MDOC_SMOFF
if (may_append && ! (mdoc->flags & (MDOC_KEEP | MDOC_SMOFF)) &&
mdoc->flags ^= MDOC_SMOFF;
mdoc->flags &= ~MDOC_SMOFF;
mdoc->flags |= MDOC_SMOFF;
mdoc->flags ^= MDOC_SMOFF;
mdoc->flags &= ~MDOC_SMOFF;
mdoc->flags |= MDOC_SMOFF;