4.5.1 Aggregation

An aggregation indicates an internal unordered part composition relationship between the whole structure, referred to as the "composite", and the subordinate components, referred to as the "parts". The concept of aggregation is used in various ways. Examples are:

Aggregation is a bi-directional relationship, the relationship from the composite to its parts is called Decomposition, and the relationship from the part to its composite is called Composition.

mvdXML Specification
<?xml version="1.0"?>
<ConceptTemplate xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" uuid="02eefcc6-b26c-4f20-9c7c-c30ae74eb9a9" name="Aggregation" status="sample" applicableSchema="IFC4" applicableEntity="IfcObjectDefinition">
  <SubTemplates>
    <ConceptTemplate uuid="ca0f65e2-3913-4fdb-8a09-0c5c7a0d5421" name="Element Composition" status="sample" applicableSchema="IFC4" applicableEntity="IfcElement">
      <Rules>
        <AttributeRule RuleID="Decomposes" AttributeName="Decomposes">
          <EntityRules>
            <EntityRule EntityName="IfcRelAggregates">
              <AttributeRules>
                <AttributeRule RuleID="RelatingObject" AttributeName="RelatingObject">
                  <EntityRules>
                    <EntityRule EntityName="IfcElement">
                      <AttributeRules>
                        <AttributeRule RuleID="ElementName" AttributeName="Name">
                          <EntityRules>
                            <EntityRule EntityName="IfcLabel" />
                          </EntityRules>
                        </AttributeRule>
                      </AttributeRules>
                    </EntityRule>
                  </EntityRules>
                </AttributeRule>
              </AttributeRules>
            </EntityRule>
          </EntityRules>
        </AttributeRule>
      </Rules>
    </ConceptTemplate>
    <ConceptTemplate uuid="8a27c15a-c4ea-4ca9-8cce-7fbba1c9bce0" name="Element Decomposition" status="sample" applicableSchema="IFC4" applicableEntity="IfcElement">
      <Rules>
        <AttributeRule RuleID="IsDecomposedBy" AttributeName="IsDecomposedBy">
          <EntityRules>
            <EntityRule EntityName="IfcRelAggregates">
              <AttributeRules>
                <AttributeRule RuleID="RelatedObjects" AttributeName="RelatedObjects">
                  <EntityRules>
                    <EntityRule EntityName="IfcElement">
                      <AttributeRules>
                        <AttributeRule RuleID="PartName" AttributeName="Name">
                          <EntityRules>
                            <EntityRule EntityName="IfcLabel" />
                          </EntityRules>
                        </AttributeRule>
                      </AttributeRules>
                    </EntityRule>
                  </EntityRules>
                </AttributeRule>
              </AttributeRules>
            </EntityRule>
          </EntityRules>
        </AttributeRule>
      </Rules>
    </ConceptTemplate>
    <ConceptTemplate uuid="8c0fd2f7-71bb-4e6e-8fdb-0c02b352f14a" name="Spatial Composition" status="sample" applicableSchema="IFC4" applicableEntity="IfcSpatialElement">
      <Rules>
        <AttributeRule AttributeName="Decomposes">
          <EntityRules>
            <EntityRule EntityName="IfcRelAggregates">
              <AttributeRules>
                <AttributeRule RuleID="RelatingObject" AttributeName="RelatingObject">
                  <EntityRules>
                    <EntityRule EntityName="IfcProject">
                      <AttributeRules>
                        <AttributeRule RuleID="ProjectName" AttributeName="Name" />
                      </AttributeRules>
                    </EntityRule>
                    <EntityRule EntityName="IfcSpatialElement">
                      <AttributeRules>
                        <AttributeRule RuleID="SpatialElementName" AttributeName="Name" />
                      </AttributeRules>
                    </EntityRule>
                  </EntityRules>
                </AttributeRule>
              </AttributeRules>
            </EntityRule>
          </EntityRules>
        </AttributeRule>
      </Rules>
    </ConceptTemplate>
    <ConceptTemplate uuid="667f8443-ecce-4a8d-a63f-931fab0453e0" name="Spatial Decomposition" status="sample" applicableSchema="IFC4" applicableEntity="IfcObjectDefinition">
      <Rules>
        <AttributeRule AttributeName="IsDecomposedBy">
          <EntityRules>
            <EntityRule EntityName="IfcRelAggregates">
              <AttributeRules>
                <AttributeRule RuleID="Type" AttributeName="RelatedObjects">
                  <EntityRules>
                    <EntityRule EntityName="IfcSpatialElement">
                      <AttributeRules>
                        <AttributeRule AttributeName="Name">
                          <EntityRules>
                            <EntityRule EntityName="IfcLabel" />
                          </EntityRules>
                        </AttributeRule>
                      </AttributeRules>
                    </EntityRule>
                  </EntityRules>
                </AttributeRule>
              </AttributeRules>
            </EntityRule>
          </EntityRules>
        </AttributeRule>
      </Rules>
    </ConceptTemplate>
  </SubTemplates>
</ConceptTemplate>

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