[PROJ] System34 height difference

[Søren Holm]

Hi

We are using proj for transformation of some Danish coordinatesystems.

Among them are S34 and DKTM.

Usually the height is not affected much during transformations. This is 
however different for S34.


$ cct -t0  +proj=pipeline +step +init=DK:DKTM1                                                                               
10 55 0 0
  263991.7405   1097565.8295        0.0000        0.0000 0


$ cct -t0  +proj=pipeline +step +init=DK:S34J                                                                                
10 55 0 0
  234033.0592     63129.6022      -36.8103        0.0000 0


Why is there ~36m subtracted for S34? 
Why is there around 0.1mm height difference for most UTM and NTM zones?
Is it the intention that the heights should be affected during these 
transformations?

-- 
Søren Holm