a) on the one hand, any worker, who, during night time, works at least three hours of his daily working time as a normal course; and b) on the other hand, any worker who is likely during night time to work a certain proportion of his annual working time, as defined at the choice of the Member State concerned: i) by national legislation, following consultation with the two sides of industry; or ii) by collective agreements or agreements concluded between the two sides of industry at national or regional level