Canon EOS 5D Mark III Instruction Manual (en)

 Customizing AF FunctionsN
During manual AF point selection, the selection can either stop at the 
outer edge or it can move to the opposite AF point. This function works 
in AF area selection modes other than 61-point automatic selection AF 
and Zone AF. (It works in 61-point automatic selection AF only with AI 
Servo AF.)
: Stops at AF area edges
Convenient if you often use an AF point 
along the edge.
: Continuous
Instead of stopping at the outer edge, the 
selected AF point continues to the 
opposite side.
You can set whether or not to display the AF point(s) in the following 
cases: 1. When selecting the AF point(s), 2. When the camera is ready 
to shoot (before AF operation), 3. During AF operation, and 4. When 
focus is achieved.
: Selected (constant)
The selected AF point(s) is always 
: All (constant)
All 61 AF points are always displayed.
: Selected (pre-AF, focused)
The selected AF point(s) is displayed for 1, 2, and 4.
: Selected (focused)
The selected AF point(s) is displayed for 1 and 4.
OFFDisable display
For 2, 3, and 4, the selected AF point(s) will not be displayed.
Manual AF point selection pattern
AF point display during focus