Namespace Xbim.Ifc4.ExternalReferenceResource Classes IfcClassification IfcClassificationReference IfcDocumentInformation IfcDocumentInformationRelationship IfcDocumentReference IfcExternalInformation IfcExternalReference IfcExternalReferenceRelationship IfcLibraryInformation IfcLibraryReference IfcResourceLevelRelationship Structs IfcLanguageId IfcURIReference Interfaces IfcClassificationReferenceSelect IfcClassificationSelect IfcDocumentSelect IfcLibrarySelect IfcResourceObjectSelect Enums IfcDocumentReference.IfcDocumentReferenceClause IfcExternalReference.IfcExternalReferenceClause