Canon EOS-1D X Manual (en)

White balance can be adjusted by setting a numerical value for color 
Select [Color temperature] from the [White balance 
adjustment] list box.
Set the color temperature.
Adjusting White Balance with Color Temperature
Displays the value of 
the setting
Drag the slider left or right
The adjustment range is 2000 to 10000K (in 10K increments).
This is a function that makes fine adjustments to the white balance. 
Using this function, you can achieve the same effects as third-party 
color temperature conversion filters and color correction filters. The 
adjustable range is 
10 steps. This function is aimed particularly at high-
end users who are familiar with the roles and effects of color 
temperature conversion filters and color correction filters.
Tune the white balance by dragging the point in the 
adjustment screen in the [Fine-tune] panel.
B stands for blue, A for amber, M for magenta and G for green. 
The color is adjusted towards the color to which the point moves.
You can also fine-tune your adjustment by using the sliders or 
entering the adjustment values.
Tuning White Balance
Enter the values to set
Drag the sliders left 
or right 
To register the adjustment outcomes as a personal white balance 
, select a setting other than [
( )] from the [White balance 
adjustment] list box before tuning the white balance. If you 
selected [
( )] from the list box and tuned the white balance, you 
cannot then register the outcomes as a personal white balance.
You cannot change or adjust the white balance in multi-exposure 
RAW images generated on the camera.
The adjustable range is 0 to 
10. (in 0.1-stop increments when 
entering a value).