Changes to 83/461/EEC: Commission Decision of 4 July 1983 laying down, for the purposes of a structure survey for 1983 as part of the programme of surveys on the structure of agricultural holdings, the definitions relating to the list of characteristics and the list of agricultural products
EU Decision 1983/461
Made by 85/643/EEC: Commission Decision of 23 December 1985 supplementing and modifying Decision 83/461/EEC laying down, for the purposes of a structure survey for 1983 as part of the programme of surveys on the structure of agricultural holdings, the definitions relating to the list of characteristics and the list of agricultural products
From legislation.gov.uk's record of changes, the official one: see it there.