A
750 version
x   y  
0   54	// comment: roll and sideslip pointer offset center of rotation
0  -40	// comment: extra clipping area for the HUD beyond the size of 'HUD_horizon-3.png'

here is an explanation on the numbers above:

the 'HUD_horizon-3.png' defines the area that is visible in the HUD... data outside of that area is clipped.
of course, you can customize that image however you like.
but, since that image is always CENTERED, you may want extra clipping area on the left, right, top or bottom,
if your HUD has a wider field of view in that area.

So, look at the two digits (0, -10) above:

the first digit is the extra left or right clipping (negative to give more area on the left, positive to give more area on right)
the second digit is the up or down clipping (negative to give more area on the bottom, positive to give more area on top)