Norwegian Mapping Authority publication 1990:1 "The transformation between ED50 and WGS84 for exploration purposes in the North Sea".
Oil and gas exploration and production.
1990 agreement between Denmark, Germany, Great Britain, Netherlands and Norway. Supersedes 1981 6-nations agreement between ED50 and WGS72 or WGS72BE. Only actively used offshore Norway but see ED50 to WGS 84 (24) (code 1613) for simpler transformation.