This unit includes the essentials of relevant standards for spatial data modelling. A number of ISO and OGC standards are available for deriving the conceptual model as well as for rules for application schemas, spatial schema provides data types for geometry models in various forms, Point, line, area, body based, temporal schema allows to consider temporal dimensions, Quality principles can be used to describe the quality of geodata, encoding standards (mainly GML) allow the standard based transfer of data and data models, CityGML allows a standard based 3D modelling, etc.