IFC 4.3.x development IfcMappedItem Semantic definitions at the entity

The IfcMappedItem is the inserted instance of a source definition (to be compared with a block / shared cell / macro definition). The instance is inserted by applying a Cartesian transformation operator as the MappingTarget.

NOTE  A mapped item is a subtype of representation item. It enables a representation to be used as a representation item in one or more other representations. The mapped item allows for the definition of a representation using other representations.

EXAMPLE  An IfcMappedItem can reuse other mapped items (ako nested blocks), doing so the IfcRepresentationMap is based on an IfcShapeRepresentation including one or more IfcMappedItem's.

NOTE  Definition according to ISO/CD 10303-43:1992
A mapped item is a type of representation item that specifies the mapping of a representation as an element of the items of a second representation.

NOTE  Entity adapted from mapped_item defined in ISO 10303-43.

HISTORY  New entity in IFC2x.

Informal Propositions:

  1. A mapped item shall not be self-defining by participating in the definition of the representation being mapped.
  2. The dimensionality of the mapping source and the mapping target has to be the same, if the mapping source is a geometric representation item. Attributes

# Attribute Type Description
LayerAssignmentSET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItemsAssignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.

> IFC2x3 CHANGE  The inverse attribute LayerAssignments has been added.

> IFC4 CHANGE  The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.
StyledByItem SET [0:1] OF IfcStyledItem FOR Item Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.

> IFC2x3 CHANGE  The inverse attribute StyledByItem has been added.
1 MappingSource IfcRepresentationMap A representation map that is the source of the mapped item. It can be seen as a block (or cell or marco) definition.
2 MappingTarget IfcCartesianTransformationOperator A representation item that is the target onto which the mapping source is mapped. It is constraint to be a Cartesian transformation operator. Entity inheritance

dot_inheritance IfcMappedItem IfcMappedItem IfcRepresentationItem IfcRepresentationItem IfcMappedItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem Formal representations

ENTITY IfcMappedItem
 SUBTYPE OF (IfcRepresentationItem);
	MappingSource : IfcRepresentationMap;
	MappingTarget : IfcCartesianTransformationOperator;