Que se passe-t-il si la sortie de la fonction MySQL TIMEDIFF() dépasse la valeur de plage du champ TIME ?

mysql> Select TIMEDIFF('2017-09-01 03:05:45','2017-10-22 03:05:45')AS 'Out of Range TIME Difference';
+------------------------------+
| Out of Range TIME Difference |
+------------------------------+
| -838:59:59                   |
+------------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> Select TIMEDIFF('2017-10-22 04:05:45','2017-09-01 03:05:45')AS 'Out of Range TIME Difference';
+------------------------------+
| Out of Range TIME Difference |
+------------------------------+
| 838:59:59                    |
+------------------------------+
1 row in set, 1 warning (0.01 sec)