#define TDB_SEQNUM 128 /* maintain a sequence number */
#define TDB_VOLATILE 256 /* Activate the per-hashchain freelist, default 5 */
#define TDB_ALLOW_NESTING 512 /* Allow transactions to nest */
+#define TDB_DISALLOW_NESTING 1024 /* Disallow transactions to nest */
/* error codes */
enum TDB_ERROR {TDB_SUCCESS=0, TDB_ERR_CORRUPT, TDB_ERR_IO, TDB_ERR_LOCK,