The International Classification of Disease (ICD) has progressed from its mid-nineteenth century origins as a short list of causes of death, to become the dominant classification of human diseases, syndromes, and conditions around the world. Despite this profound increase in content and impact over more than a century between the initial versions of the International Statistical List and the release of ICD-10 in 1990, there as virtually no evolution of the structure or architecture of the classification. It remained essentially a table of terms with associated code values and very little more. Some have characterized the ICD as a 16th century spreadsheet, harkening to the structure of the ICD’s ancient predecessor, the London Bills of Mortality established during the reign of Henry VIII of England.