References The following normative documents are referenced in this document. OGC 17-069, OGC Web Feature Service 3.0: Part 1 - Core, Version 3.0.0-draft.1 OGC 12-019, OGC City Geography Markup Language (CityGML) Encoding Standard 2.0 OGC 15-001r4, OGC 3D Portrayal Service 1.0 OpenAPI Specification 3.0.1