The ED50 to ED87 North Sea Transformation consists of a 4th order reversible polynomial that is used to convert coordinates between the ED50 and ED87 datums.
This formula was published in a 1991 note created by the Norwegian Mapping Authority (Statens Kartverk) entitled "Om Transformasjon mellom Geodetiske Datum i Norge".
The "ED50 To ED87 NorthSea" transformation method is hard-coded and does not require any Parameters.