Nikon D6 Reference Manual page 865

a12: Auto-Area AF Starting Point
Selecting [Enable] lets you use the multi selector to choose the
starting focus point when AF-C and [Auto-area AF] are selected
respectively for AF mode and AF-area mode. The camera will
revert to normal auto-area AF once you have focused on the
subject in the selected focus point.
a13: Focus-Point Persistence
Choose whether the focus point selected by the camera
continues in use after you change AF-area modes using a
control to which [AF-area mode] or [AF-area mode + AF-ON]
has been assigned via Custom Setting f3 [Custom controls].
This only applies if you change AF-area modes while focusing
with the shutter-release button pressed halfway.
•
Focus-point persistence applies if while the control is pressed,
you switch from an AF-area mode such as [Auto-area AF] in
which the focus point is chosen automatically to a mode in
which the focus point is selected manually.
G button U A Custom Settings menu
G button U A Custom Settings menu
A Custom Settings: Fine-Tuning Camera Settings 813