The official transformation parameters from EPSG:31254 to WGS84 are:
towgs84=577.326,90.129,463.919,5.137,1.474,5.297,2.4232 (EPSG:1618)
(defined here and used by ArcGIS MGI_To_WGS_1984_3 transformation method as well as in the EPSG:31254 definition used by QGis 2.18.1)
GeoServer 2.11.0 on the other hand uses the following transformation parameters in its EPSG:31254 definition:
TOWGS84[601.705, 84.263, 485.227, 4.7354, -1.3145, -5.393, -2.3887].
If I provide GeoServer with an alternate version of EPSG:31254 by using the epsg_overrides.properties file - using the EPSG:1618 transformation parameters - the layer is displayed in the wrong position (way off).
Question:
Why does GeoServer use these transformation parameters and not the official ones, and where does it get them from?
Why don't the official parameters work with GeoServer?