Key Entities DataEntity : which consists of aggregations of more Data entities DataProductionTool: which characterizes the instruments and/or processes available for producing data Observation Station: which characterizes the location(s) (and observers) of data production Activity: which characterizes the projects and campaigns etc., associated with data production These four key entities are related by the Deployment, which binds a production tool deployed at an observation station on behalf of an activity to produce data.