Where can I find the "aircraft home" also called "standard flight simulator center point" in the SDK manual ?

I just know it is NOT the the reference_datum_position (see http://msdn.microsoft.com/en-us/library/cc526949.aspx#mozTocId243173)

the reference_datum_position is given in the aircaft.cfg. The aircraft home or standard center point can't be found in the aircaft.cfg

Would be fine to know where to find it

It's complex. :(

This is from the FSX SDK:

reference_datum_position
Offset (in feet) of the aircraft's reference datum from the standard Flight Simulator center point, which is on the centerline chord aft of the leading edge. 
By setting the Reference Datum Position, actual aircraft loading data can be used directly according to the aircraft's manufacturer.
If not specified, the default is 0,0,0.
Aircreation582SL( reference_datum_position= 0.000, 0.000, 0.000 )
Boeing 747-400( reference_datum_position = 83.5, 0, 0 )
Beech Baron 58( reference_datum_position = 6.96, 0, 0 )

Acceleration FA-18: reference_datum_position     =   29.00,  0, 0    // (feet) distance from FlightSim Reference position, which is: (1/4 chord, centerline, waterline)

So in the Acceleration FA-18, the standard Flight Simulator center point is 29 feet forward of, but neither left/right nor above/below the datum_reference_point.

That should really boggle your mind! It takes a bit to figure it out in your head, but that's just how it is.

[edit]I find it harder to explain it to you, than I do to figure it out in my head! :([/edit]

Thanks very much Mark, this is clear enough, so far !

To progress a little bit further I just need to find 1) what is the HUD center point position (x,y,z) relative to the standard flight simulator center point and 2) the HUD radius. Those values are all given in feet.

the eypoint format is y,x,z (feet)
the collimation format is x,y',z,radius (feet)

in both formats x and z are the same, the y value is not (noted y'). Is it always like this, whatever the aircraft ?

Let's see 2 examples :

CS F/A-18 eyepoint -17.00,0.000,3.358 collimation 0.0,14.01,3.3580,0.307
F/A-18 + mod eyepoint -17.00,0.000,3.380 collimation 0.0,14.40,3.3800,0.310
for both these a/c the standard FS center point is 29 feet forward of the datum_reference_point

Last question : the CS Weapon VC hud3d width, height, hor. size, vert. size are all given in pixels. How can I convert feet in pixels depending on the monitor resolution ? mine is 1920*1080

PS just found how to convert feet in pixels with the ppi = pixel per inch formula

http://en.wikipedia.org/wiki/Pixel_density