Presented in this volume is the set of internationally agreed scientific and technical characteristics by which every spatial metadata standard in the world can be assessed and understood. Created by the members of the International Cartographic Association (ICA) Spatial Data Standards Commission after 6 years of study, these characteristics and obligation parameters recognize almost every possible capability that a spatial metadata standard might have. The set consists of 12 broad primary level characteristics, and approximately 60 secondary and 200 tertiary characteristics.