Prior to 1997, Australian mortality data were assigned a single Underlying cause of death (UCoD). This took the form of a code indicating what had caused an injury to occur. From 1997 onward, up to 13, and later up to 20, Multiple causes of death (MCoDs) could be allocated to any death record. These MCoDs represent nearly all of the information about cause of death that appeared on the death certificate. Of particular interest for injury surveillance was the fact that these Multiple causes of death could identify not only the external cause of an injury, but could also provide information about the nature of the injury.