System variable for current Z machine position

I ended up using not Andy method (I did not tested), but Alans:

#5213 + #5223 + #5422

Gives me the correct Z machine position. Nice and easy.

I know it's a very old topic but it partly gives me the answer of my problem.

I think a more generic formula to obtain absolute Z position in whatever coordinate system is :
Perhaps it can help someone else (if I made no mistake).

If version 2.9 is used,  #<_abs_z>  return machine coordinates, G53

Good news ... but still in 2.8 for now.