From Fmepedia

Converting between the DHDN datum and the WGS84 or ETRS89 datums

By default, the 1995 translation parameters are used to convert between the DHDN and WSG84/ETRS89 datums.

To use the 2001 translation parameters to convert between the DHDN and WGS84/ETRS89 datums, add the following entry to your MyCoordSysDefs.fme file:

DATUM_DEF DHDN                            \
   DESC_NM "Deutsches Hauptdreiecksnetz"  \
   ELLIPSOID BESSEL                       \
   USE 7PARAMETER                         \
   DELTA_X 598.1                          \
   DELTA_Y  73.7                          \
   DELTA_Z 418.2                          \
   ROT_X    -0.202                        \
   ROT_Y    -0.045                        \
   ROT_Z     2.455                        \
   BWSCALE   6.70

To use the BeTA 2007 grid shift file to transform between the DHDN and WGS84/ETRS89 datums, add the following entry to your MyCoordSysDefs.fme file:

DATUM_DEF DHDN                            \
   DESC_NM "Deutsches Hauptdreiecksnetz"  \
   ELLIPSOID BESSEL                       \
   USE DHDN                               \
   DELTA_X 582                            \
   DELTA_Y 105                            \
   DELTA_Z 414                            \
   ROT_X    -1.04                         \
   ROT_Y    -0.35                         \
   ROT_Z     3.08                         \
   BWSCALE   8.3

... and then comment out a line in DhdnToEtrs89.gdc, changing:

Fallback=DHDN

... to:

#Fallback=DHDN

These definitions affect all of the coordinate systems that use the DHDN datum:

- DHDN.Berlin/Cassini
- DHDN.Gauss3d-2
- DHDN.Gauss3d-3
- DHDN.Gauss3d-4
- DHDN.Gauss3d-5
- DHDN.LL