#define ADFLAGS_TRUNC (1<<12) /* truncate, open called with O_TRUNC */
#define ADVOL_NODEV (1 << 0)
+#define ADVOL_RO (1 << 1)
#define ADVOL_UNIXPRIV (1 << 2) /* adouble unix priv */
#define ADVOL_INVDOTS (1 << 3) /* dot files (.DS_Store) are invisible) */
#define ADVOL_FOLLO_SYML (1 << 4)