The International Maritime Organization (IMO) describes direct reduced iron under the following categories: DRI (A) Hot-moulded briquettes; DRI (B) Pellets, lumps and cold-moulded briquettes; DRI (C) By-product fines.
DRI A:Direct Reduced Iron (A) Briquettes, Hot-Moulded This form of iron ore is also marketed and referred to as HBI (Hot Briquetted Iron). Material produced by removing oxygen from iron ore by reaction with hydrogen and carbon monoxide at a high temperature. A premium quality, high density material that contains the highest levels of Fe content.
DRI B:Direct Reduced Iron (B) Pellets, Lumps and Cold-Moulded Briquettes Material produced by the  removal of oxygen at temperatures below the fusion point of iron. Cold-moulded briquettes are defined as those which have been moulded at a temperature of under 650*C or which have a density of less than 5.0 g/cm3.
DRI C:By-product Fines Material generated as a by-product of the manufacturing and handling process of DRI(A) and/or DRI (B). Average particle size is less than 6.35mm.