comprise anthracite (as to approximately 60 to 80 per cent of the total weight), petroleum coke (as to approximately 10 to 30 per cent of the total weight) and a molasses and phosphoric acid binder (as to the remaining weight);

were manufactured from those constituents by a process involving roll-pressing and heat treatment at about 300°C;

are pillow-shaped briquettes marked with a single indented line running longitudinally along each face, offset from its counterpart by 10 millimetres or unmarked;

have an average weight of 80 grammes per briquette; and

have a sulphur content not exceeding 2 per cent of the total weight.