Can anyone explain Cusom Settings C2-10&11

I've set a custom white balance for flash set up but not sure how to set these two functions
Thanks in advance. David

10. WB Adjustable
Range
Sets whether to automatically fine-tune
the white balance when specifying the
light source on the white balance
setting.
p.206
11. WB When Using
Flash
Sets the white balance setting when
using flash. p.206

WB adjustable range means that if you set a WB, say Daylight, the camewra will still make fine adjustments over a small range. I switch this off. If I set daylight, I mean daylight....

WB when using flash means when the flash is acivated any other WB set is overridden in favour of whatever is selected with this function.