EN/CityGML-Tutorial/chapter-2:-Building/LOD2.md

-In LOD2, the shape of roof can be modeled in addition to LOD1. Additionally, starting from LOD2 semantic properties such as BoundarySurfaces (e.g. WallSurface, GroundSurface, RoofSurface, ClosureSurface) can be modeled using CityGML property of "boundedBy". Moreover, building elements such as columns, vestibules,bay windows, balconies, dormer windows and turrets can be optionally incorporated into the building's LOD2 geometries as BuildingInstallation objects.  A simplified UML diagram of CityGML 2.0 LOD2 building object is shown below:
+In LOD2, the shape of roof can be modeled in addition to LOD1. Additionally, starting from LOD2 semantic properties such as BoundarySurfaces (e.g. WallSurface, GroundSurface, RoofSurface, ClosureSurface) can be modeled using CityGML property of "boundedBy". Moreover, building elements such as columns, vestibules, bay windows, balconies, dormer windows and turrets can be optionally incorporated into the building's LOD2 geometries as BuildingInstallation objects. A simplified UML diagram of CityGML 2.0 LOD2 building object is shown below:
 
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@@ -6,7 +6,7 @@ In LOD2, the shape of roof can be modeled in addition to LOD1. Additionally, sta
 
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-For the geometries of a LOD2 building, the CityGML 2.0 standard allows the use of MultiSurface elements. However, a MultiSurface geometry does not guarantee the necessary topological connection of its surfaces. Based on use case, it is recommended to model BoundarySurfaces as MultiSurface (e.g. for visualization purpose) and a building with solid geometry (e.g. for building energy demand simulation). The [CityGML standard](https://portal.opengeospatial.org/files/?artifact_id=47842) conformance 10.3.9.4, page 78, requires that a solid geometry must be inserted using references to the polygons of their respective boundary surfaces. These references have to be made using xlink concept of GML 3.1.1. More information on correctly inserting solid geometries to CityGML building object can be found [here](https://gitlab.com/volkercoors/CiD4Sim/-/wikis/usefulTools/FME-Workbenches-(EN)).
+For the geometries of a LOD2 building, the CityGML 2.0 standard allows the use of MultiSurface elements. However, a MultiSurface geometry does not guarantee the necessary topological connection of its surfaces. Based on use case, it is recommended to model BoundarySurfaces as MultiSurface (e.g. for visualization purpose) and a building with solid geometry (e.g. for building energy demand simulation). The [CityGML standard](https://portal.opengeospatial.org/files/?artifact_id=47842) conformance 10.3.9.4, page 78, requires that a solid geometry starting from LOD2 must be inserted using references to the polygons of their respective boundary surfaces. These references have to be made using xlink concept of GML 3.1.1. More information on correctly inserting solid geometries to CityGML building object can be found [here](https://gitlab.com/volkercoors/CiD4Sim/-/wikis/usefulTools/FME-Workbenches-(EN)).
 
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