Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 311)

AF3
(1) Electronic full-time MF
(2) Lens electronic MF
(3) AF-assist beam firing
(4) One-Shot AF release prior.
AF4
(1) Subject tracking settings
(2) Lens drive when AF impossible
(3) Selectable AF point
(4) Select AF area selec. mode
(5) AF area selection method
(6) Orientation linked AF point
(7) Initial Servo AF pt, /
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