Canon EOS-1D X Mark III Advanced User's Manual page 142

Caution
During white balance bracketing, the maximum burst for continuous shooting will
be lower.
Since three images are recorded for one shot, it takes longer to record the image to
the card.
Note
You can also set white balance correction and AEB together with white balance
bracketing. If you set AEB in combination with white balance bracketing, a total of
nine images will be recorded for a single shot.
The white balance icon blinks to indicate that white balance bracketing has been
set.
You can change the bracketing sequence (
white balance bracketing.
Bracket stands for bracketing.
) and number of shots (
142
) for the