diff --git a/CityGML/Schema/cityGMLBase.xsd b/CityGML/Schema/cityGMLBase.xsd
index 91d9c74..35926d0 100644
--- a/CityGML/Schema/cityGMLBase.xsd
+++ b/CityGML/Schema/cityGMLBase.xsd
@@ -118,7 +118,9 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
   </complexType>
   <element abstract="true" name="AbstractGenericAttribute" substitutionGroup="gml:AbstractObject" type="core:AbstractGenericAttributeType"/>
   <complexType abstract="true" name="AbstractGenericAttributeType">
-    <sequence/>
+    <sequence>
+      <element name="name" type="string"/>
+    </sequence>
   </complexType>
   <complexType name="AbstractGenericAttributePropertyType">
     <sequence>
@@ -126,7 +128,11 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
     </sequence>
   </complexType>
   <element abstract="true" name="AbstractGenericApplicationPropertyOfAbstractLogicalSpace" type="anyType"/>
-  <element abstract="true" name="AbstractLogicalSpace" substitutionGroup="core:AbstractSpace" type="core:AbstractLogicalSpaceType"/>
+  <element abstract="true" name="AbstractLogicalSpace" substitutionGroup="core:AbstractSpace" type="core:AbstractLogicalSpaceType">
+    <annotation>
+      <documentation>A logical space is a space that is not bounded by physical surfaces but is defined according to thematic considerations.</documentation>
+    </annotation>
+  </element>
   <complexType abstract="true" name="AbstractLogicalSpaceType">
     <complexContent>
       <extension base="core:AbstractSpaceType">
@@ -144,7 +150,11 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
     <attributeGroup ref="gml:OwnershipAttributeGroup"/>
   </complexType>
   <element abstract="true" name="AbstractGenericApplicationPropertyOfAbstractOccupiedSpace" type="anyType"/>
-  <element abstract="true" name="AbstractOccupiedSpace" substitutionGroup="core:AbstractPhysicalSpace" type="core:AbstractOccupiedSpaceType"/>
+  <element abstract="true" name="AbstractOccupiedSpace" substitutionGroup="core:AbstractPhysicalSpace" type="core:AbstractOccupiedSpaceType">
+    <annotation>
+      <documentation>An occupied space represents a physical volumetric object that is partially or entirely filled with matter.</documentation>
+    </annotation>
+  </element>
   <complexType abstract="true" name="AbstractOccupiedSpaceType">
     <complexContent>
       <extension base="core:AbstractPhysicalSpaceType">
@@ -177,7 +187,11 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
     <attributeGroup ref="gml:OwnershipAttributeGroup"/>
   </complexType>
   <element abstract="true" name="AbstractGenericApplicationPropertyOfAbstractPhysicalSpace" type="anyType"/>
-  <element abstract="true" name="AbstractPhysicalSpace" substitutionGroup="core:AbstractSpace" type="core:AbstractPhysicalSpaceType"/>
+  <element abstract="true" name="AbstractPhysicalSpace" substitutionGroup="core:AbstractSpace" type="core:AbstractPhysicalSpaceType">
+    <annotation>
+      <documentation>A physical space is a space that is fully or partially bounded by physical objects.</documentation>
+    </annotation>
+  </element>
   <complexType abstract="true" name="AbstractPhysicalSpaceType">
     <complexContent>
       <extension base="core:AbstractSpaceType">
@@ -229,7 +243,11 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
     <attributeGroup ref="gml:OwnershipAttributeGroup"/>
   </complexType>
   <element abstract="true" name="AbstractGenericApplicationPropertyOfAbstractSpace" type="anyType"/>
-  <element abstract="true" name="AbstractSpace" substitutionGroup="core:AbstractCityObject" type="core:AbstractSpaceType"/>
+  <element abstract="true" name="AbstractSpace" substitutionGroup="core:AbstractCityObject" type="core:AbstractSpaceType">
+    <annotation>
+      <documentation>A Space is an entity of volumetric extent in the real world.</documentation>
+    </annotation>
+  </element>
   <complexType abstract="true" name="AbstractSpaceType">
     <complexContent>
       <extension base="core:AbstractCityObjectType">
@@ -306,17 +324,30 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
     <attributeGroup ref="gml:OwnershipAttributeGroup"/>
   </complexType>
   <element abstract="true" name="AbstractGenericApplicationPropertyOfAbstractThematicSurface" type="anyType"/>
-  <element abstract="true" name="AbstractThematicSurface" substitutionGroup="core:AbstractCityObject" type="core:AbstractThematicSurfaceType"/>
+  <element abstract="true" name="AbstractThematicSurface" substitutionGroup="core:AbstractCityObject" type="core:AbstractThematicSurfaceType">
+    <annotation>
+      <documentation>A Space Boundary is an entity with areal extent in the real world.
+Space Boundaries are objects that bound a Space. They also realize the contact between adjacent spaces.</documentation>
+    </annotation>
+  </element>
   <complexType abstract="true" name="AbstractThematicSurfaceType">
     <complexContent>
       <extension base="core:AbstractCityObjectType">
         <sequence>
+          <element maxOccurs="unbounded" minOccurs="0" name="bounds" type="core:AbstractSpacePropertyType">
+            <annotation>
+              <appinfo>
+                <reversePropertyName xmlns="http://www.opengis.net/gml/3.2">core:boundary</reversePropertyName>
+              </appinfo>
+            </annotation>
+          </element>
           <element maxOccurs="unbounded" minOccurs="0" name="area" type="core:QualifiedAreaPropertyType"/>
           <element minOccurs="0" name="lod0MultiCurve" type="gml:MultiCurvePropertyType">
             <annotation>
               <documentation>Relation to a  LOD0 curve geometry of AbstractSpace.</documentation>
             </annotation>
           </element>
+          <element minOccurs="0" name="lod0MultiSurface" type="gml:MultiSurfacePropertyType"/>
           <element minOccurs="0" name="lod1MultiSurface" type="gml:MultiSurfacePropertyType">
             <annotation>
               <documentation>Relation to a  LOD1 surface geometry of AbstractSpaceBoundary.</documentation>
@@ -332,13 +363,6 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
               <documentation>Relation to a  LOD3 surface geometry of AbstractSpaceBoundary.</documentation>
             </annotation>
           </element>
-          <element maxOccurs="unbounded" minOccurs="0" name="bounds" type="core:AbstractSpacePropertyType">
-            <annotation>
-              <appinfo>
-                <reversePropertyName xmlns="http://www.opengis.net/gml/3.2">core:boundary</reversePropertyName>
-              </appinfo>
-            </annotation>
-          </element>
           <element minOccurs="0" name="pointCloud" type="core:AbstractPointCloudPropertyType"/>
           <element maxOccurs="unbounded" minOccurs="0" ref="core:AbstractGenericApplicationPropertyOfAbstractThematicSurface"/>
         </sequence>
@@ -353,7 +377,11 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
     <attributeGroup ref="gml:OwnershipAttributeGroup"/>
   </complexType>
   <element abstract="true" name="AbstractGenericApplicationPropertyOfAbstractUnoccupiedSpace" type="anyType"/>
-  <element abstract="true" name="AbstractUnoccupiedSpace" substitutionGroup="core:AbstractPhysicalSpace" type="core:AbstractUnoccupiedSpaceType"/>
+  <element abstract="true" name="AbstractUnoccupiedSpace" substitutionGroup="core:AbstractPhysicalSpace" type="core:AbstractUnoccupiedSpaceType">
+    <annotation>
+      <documentation>An unoccupied space represents physical volumetric entity that is entirely or mostly free of matter.</documentation>
+    </annotation>
+  </element>
   <complexType abstract="true" name="AbstractUnoccupiedSpaceType">
     <complexContent>
       <extension base="core:AbstractPhysicalSpaceType">
@@ -522,6 +550,7 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
     <complexContent>
       <extension base="gml:AbstractGMLType">
         <sequence>
+          <element maxOccurs="unbounded" minOccurs="0" name="genericAttribute" type="core:AbstractGenericAttributePropertyType"/>
           <element name="relationType" type="gml:CodeType"/>
           <element name="relatedTo" type="core:AbstractCityObjectPropertyType"/>
         </sequence>
@@ -536,7 +565,11 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
     <attributeGroup ref="gml:OwnershipAttributeGroup"/>
   </complexType>
   <element abstract="true" name="AbstractGenericApplicationPropertyOfClosureSurface" type="anyType"/>
-  <element name="ClosureSurface" substitutionGroup="core:AbstractThematicSurface" type="core:ClosureSurfaceType"/>
+  <element name="ClosureSurface" substitutionGroup="core:AbstractThematicSurface" type="core:ClosureSurfaceType">
+    <annotation>
+      <documentation>SIG3D: Exterior or interior boundary surface providing virtual boundaries, typically used to seal holes in volumetric objects.</documentation>
+    </annotation>
+  </element>
   <complexType name="ClosureSurfaceType">
     <complexContent>
       <extension base="core:AbstractThematicSurfaceType">
@@ -587,44 +620,51 @@ AbstractCityObject relative to the surrounding terrain.</documentation>
       <element ref="core:ExternalReference"/>
     </sequence>
   </complexType>
-  <element name="ImplicitGeometry" substitutionGroup="gml:AbstractObject" type="core:ImplicitGeometryType">
+  <element name="ImplicitGeometry" substitutionGroup="gml:AbstractGML" type="core:ImplicitGeometryType">
     <annotation>
       <documentation>SIG3D: A  geometric representation where the shape is stored only once as a prototypical geometry, for example a tree or other vegetation object, a traffic light or a traffic sign. This prototypic geometry object can be re-used or referenced many times, wherever the corresponding feature occurs in the 3D city model.</documentation>
     </annotation>
   </element>
   <complexType name="ImplicitGeometryType">
-    <sequence>
-      <element name="transformationMatrix" type="core:TransformationMatrix4x4Type">
-        <annotation>
-          <documentation>SIG3D: Mathematical transformation (translation, rotation and scaling) between the prototype geometry and the actual spatial position of the object.</documentation>
-        </annotation>
-      </element>
-      <element minOccurs="0" name="mimeType" type="gml:CodeType">
-        <annotation>
-          <documentation>SIG3D: Mime type of the referenced external geometric object (attribute libraryObject).</documentation>
-        </annotation>
-      </element>
-      <element minOccurs="0" name="libraryObject" type="anyURI">
-        <annotation>
-          <documentation>SIG3D: External link to a prototype geometry.</documentation>
-        </annotation>
-      </element>
-      <element name="referencePoint" type="gml:PointPropertyType">
-        <annotation>
-          <documentation>SIG3D: Base point of the object in the world coordinate system.</documentation>
-        </annotation>
-      </element>
-      <element minOccurs="0" name="relativeGMLGeometry" type="gml:GeometryPropertyType">
-        <annotation>
-          <documentation>SIG3D: Geometry of the prototype, specified in a local coordinate system.</documentation>
-        </annotation>
-      </element>
-    </sequence>
+    <complexContent>
+      <extension base="gml:AbstractGMLType">
+        <sequence>
+          <element name="transformationMatrix" type="core:TransformationMatrix4x4Type">
+            <annotation>
+              <documentation>SIG3D: Mathematical transformation (translation, rotation and scaling) between the prototype geometry and the actual spatial position of the object.</documentation>
+            </annotation>
+          </element>
+          <element minOccurs="0" name="mimeType" type="gml:CodeType">
+            <annotation>
+              <documentation>SIG3D: Mime type of the referenced external geometric object (attribute libraryObject).</documentation>
+            </annotation>
+          </element>
+          <element minOccurs="0" name="libraryObject" type="anyURI">
+            <annotation>
+              <documentation>SIG3D: External link to a prototype geometry.</documentation>
+            </annotation>
+          </element>
+          <element name="referencePoint" type="gml:PointPropertyType">
+            <annotation>
+              <documentation>SIG3D: Base point of the object in the world coordinate system.</documentation>
+            </annotation>
+          </element>
+          <element minOccurs="0" name="relativeGMLGeometry" type="gml:GeometryPropertyType">
+            <annotation>
+              <documentation>SIG3D: Geometry of the prototype, specified in a local coordinate system.</documentation>
+            </annotation>
+          </element>
+          <element maxOccurs="unbounded" minOccurs="0" name="appearance" type="core:AbstractAppearancePropertyType"/>
+        </sequence>
+      </extension>
+    </complexContent>
   </complexType>
   <complexType name="ImplicitGeometryPropertyType">
-    <sequence>
+    <sequence minOccurs="0">
       <element ref="core:ImplicitGeometry"/>
     </sequence>
+    <attributeGroup ref="gml:AssociationAttributeGroup"/>
+    <attributeGroup ref="gml:OwnershipAttributeGroup"/>
   </complexType>
   <simpleType name="IntegerBetween0and3Type">
     <restriction base="integer">
diff --git a/CityGML/Schema/generics.xsd b/CityGML/Schema/generics.xsd
index 4ed3e10..04430d4 100644
--- a/CityGML/Schema/generics.xsd
+++ b/CityGML/Schema/generics.xsd
@@ -5,29 +5,14 @@
   <import namespace="http://www.opengis.net/citygml/3.0" schemaLocation="./cityGMLBase.xsd"/>
   <import namespace="http://www.opengis.net/gml/3.2" schemaLocation="http://schemas.opengis.net/gml/3.2.1/gml.xsd"/>
   <!--XML Schema document created by ShapeChange - http://shapechange.net/-->
-  <element abstract="true" name="AbstractGenericAttribute" substitutionGroup="core:AbstractGenericAttribute" type="gen:AbstractGenericAttributeType"/>
-  <complexType abstract="true" name="AbstractGenericAttributeType">
-    <complexContent>
-      <extension base="core:AbstractGenericAttributeType">
-        <sequence>
-          <element name="name" type="string"/>
-        </sequence>
-      </extension>
-    </complexContent>
-  </complexType>
-  <complexType name="AbstractGenericAttributePropertyType">
-    <sequence>
-      <element ref="gen:AbstractGenericAttribute"/>
-    </sequence>
-  </complexType>
-  <element name="DateAttribute" substitutionGroup="gen:AbstractGenericAttribute" type="gen:DateAttributeType">
+  <element name="DateAttribute" substitutionGroup="core:AbstractGenericAttribute" type="gen:DateAttributeType">
     <annotation>
       <documentation>SIG3D: Generic Attribute of type "date".</documentation>
     </annotation>
   </element>
   <complexType name="DateAttributeType">
     <complexContent>
-      <extension base="gen:AbstractGenericAttributeType">
+      <extension base="core:AbstractGenericAttributeType">
         <sequence>
           <element name="value" type="date">
             <annotation>
@@ -43,14 +28,14 @@
       <element ref="gen:DateAttribute"/>
     </sequence>
   </complexType>
-  <element name="DoubleAttribute" substitutionGroup="gen:AbstractGenericAttribute" type="gen:DoubleAttributeType">
+  <element name="DoubleAttribute" substitutionGroup="core:AbstractGenericAttribute" type="gen:DoubleAttributeType">
     <annotation>
       <documentation>SIG3D: Generic Attribute of type "double".</documentation>
     </annotation>
   </element>
   <complexType name="DoubleAttributeType">
     <complexContent>
-      <extension base="gen:AbstractGenericAttributeType">
+      <extension base="core:AbstractGenericAttributeType">
         <sequence>
           <element name="value" type="double">
             <annotation>
@@ -66,21 +51,21 @@
       <element ref="gen:DoubleAttribute"/>
     </sequence>
   </complexType>
-  <element name="GenericAttributeSet" substitutionGroup="gen:AbstractGenericAttribute" type="gen:GenericAttributeSetType">
+  <element name="GenericAttributeSet" substitutionGroup="core:AbstractGenericAttribute" type="gen:GenericAttributeSetType">
     <annotation>
       <documentation>SIG3D: Set of Generic Attributes.</documentation>
     </annotation>
   </element>
   <complexType name="GenericAttributeSetType">
     <complexContent>
-      <extension base="gen:AbstractGenericAttributeType">
+      <extension base="core:AbstractGenericAttributeType">
         <sequence>
           <element minOccurs="0" name="codeSpace" type="anyURI">
             <annotation>
               <documentation>SIG3D: Codespace idcentifier of the Generic AttributeSet.</documentation>
             </annotation>
           </element>
-          <element maxOccurs="unbounded" name="genericAttribute" type="gen:AbstractGenericAttributePropertyType"/>
+          <element maxOccurs="unbounded" name="genericAttribute" type="core:AbstractGenericAttributePropertyType"/>
         </sequence>
       </extension>
     </complexContent>
@@ -90,23 +75,6 @@
       <element ref="gen:GenericAttributeSet"/>
     </sequence>
   </complexType>
-  <element name="GenericCityObjectRelation" substitutionGroup="core:CityObjectRelation" type="gen:GenericCityObjectRelationType"/>
-  <complexType name="GenericCityObjectRelationType">
-    <complexContent>
-      <extension base="core:CityObjectRelationType">
-        <sequence>
-          <element maxOccurs="unbounded" minOccurs="0" name="genericAttribute" type="gen:AbstractGenericAttributePropertyType"/>
-        </sequence>
-      </extension>
-    </complexContent>
-  </complexType>
-  <complexType name="GenericCityObjectRelationPropertyType">
-    <sequence minOccurs="0">
-      <element ref="gen:GenericCityObjectRelation"/>
-    </sequence>
-    <attributeGroup ref="gml:AssociationAttributeGroup"/>
-    <attributeGroup ref="gml:OwnershipAttributeGroup"/>
-  </complexType>
   <element abstract="true" name="AbstractGenericApplicationPropertyOfGenericLogicalSpace" type="anyType"/>
   <element name="GenericLogicalSpace" substitutionGroup="core:AbstractLogicalSpace" type="gen:GenericLogicalSpaceType"/>
   <complexType name="GenericLogicalSpaceType">
@@ -191,14 +159,14 @@
     <attributeGroup ref="gml:AssociationAttributeGroup"/>
     <attributeGroup ref="gml:OwnershipAttributeGroup"/>
   </complexType>
-  <element name="IntAttribute" substitutionGroup="gen:AbstractGenericAttribute" type="gen:IntAttributeType">
+  <element name="IntAttribute" substitutionGroup="core:AbstractGenericAttribute" type="gen:IntAttributeType">
     <annotation>
       <documentation>SIG3D: Generic Attribute of type "integer".</documentation>
     </annotation>
   </element>
   <complexType name="IntAttributeType">
     <complexContent>
-      <extension base="gen:AbstractGenericAttributeType">
+      <extension base="core:AbstractGenericAttributeType">
         <sequence>
           <element name="value" type="integer">
             <annotation>
@@ -214,14 +182,14 @@
       <element ref="gen:IntAttribute"/>
     </sequence>
   </complexType>
-  <element name="MeasureAttribute" substitutionGroup="gen:AbstractGenericAttribute" type="gen:MeasureAttributeType">
+  <element name="MeasureAttribute" substitutionGroup="core:AbstractGenericAttribute" type="gen:MeasureAttributeType">
     <annotation>
       <documentation>SIG3D: Generic Attribute of type "Measure" (double-attribute with explicit specification of a unit-of-measurement).</documentation>
     </annotation>
   </element>
   <complexType name="MeasureAttributeType">
     <complexContent>
-      <extension base="gen:AbstractGenericAttributeType">
+      <extension base="core:AbstractGenericAttributeType">
         <sequence>
           <element name="value" type="gml:MeasureType">
             <annotation>
@@ -237,14 +205,14 @@
       <element ref="gen:MeasureAttribute"/>
     </sequence>
   </complexType>
-  <element name="StringAttribute" substitutionGroup="gen:AbstractGenericAttribute" type="gen:StringAttributeType">
+  <element name="StringAttribute" substitutionGroup="core:AbstractGenericAttribute" type="gen:StringAttributeType">
     <annotation>
       <documentation>SIG3D: Generic Attribute of type "string".</documentation>
     </annotation>
   </element>
   <complexType name="StringAttributeType">
     <complexContent>
-      <extension base="gen:AbstractGenericAttributeType">
+      <extension base="core:AbstractGenericAttributeType">
         <sequence>
           <element name="value" type="string">
             <annotation>
@@ -260,14 +228,14 @@
       <element ref="gen:StringAttribute"/>
     </sequence>
   </complexType>
-  <element name="UriAttribute" substitutionGroup="gen:AbstractGenericAttribute" type="gen:UriAttributeType">
+  <element name="UriAttribute" substitutionGroup="core:AbstractGenericAttribute" type="gen:UriAttributeType">
     <annotation>
       <documentation>SIG3D: Generic Attribute of type "URI".</documentation>
     </annotation>
   </element>
   <complexType name="UriAttributeType">
     <complexContent>
-      <extension base="gen:AbstractGenericAttributeType">
+      <extension base="core:AbstractGenericAttributeType">
         <sequence>
           <element name="value" type="anyURI">
             <annotation>