IfcEdgeLoop

BACnet MVD

#### IfcEdgeLoop

Natural language names

| Kante als Schleife
| Edge Loop

##### Semantic definitions at the entity

Entity definition

> NOTE Definition according to ISO/CD 10303-42:1992
> An edge_loop is a loop with nonzero extent. It is a path in which the start and end vertices are the same. Its domain, if present, is a closed curve. An edge_loop may overlap itself.

> NOTE Entity adapted from edge_loop defined in ISO 10303-42.

> HISTORY New entity in IFC2x2.

Informal Propositions:

1. The genus of the IfcEdgeLoop shall be 1 or greater.
2. The Euler formula shall be satisfied:
   (number of vertices) + genus - (number of edges) = 1;
3. No edge may be referenced more than once by the same IfcEdgeLoop with the same sense. For this purpose, an edge which is not an oriented edge is considered to be referenced with the sense TRUE.

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
1 | EdgeList | IfcOrientedEdge | L[1:?] | A list of oriented edge entities which are concatenated together to form this path. | X | X
| Ne :=SIZEOF(EdgeList) | IfcInteger |  | The number of elements in the edge list. | X | X

Formal Propositions

Rule | Description
--- | ---
IsClosed | The start vertex of the first edge shall be the same as the end vertex of the last edge. This ensures that the path is closed to form a loop.
IsContinuous | The end vertex of each edge shall be the same as the start vertex of its successor.

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
IfcRepresentationItem

LayerAssignment

IfcPresentationLayerAssignment
@AssignedItems

S[0:1]

Assignment 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.

X

StyledByItem

IfcStyledItem
@Item

S[0:1]

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.

X

X

IfcTopologicalRepresentationItem
IfcLoop
IfcEdgeLoop
1 | EdgeList | IfcOrientedEdge | L[1:?] | A list of oriented edge entities which are concatenated together to form this path. | X | X
| Ne :=SIZEOF(EdgeList) | IfcInteger |  | The number of elements in the edge list. | X | X

##### Formal representations

XML Specification
`<xs:element name="IfcEdgeLoop" type="ifc:IfcEdgeLoop" substitutionGroup="ifc:IfcLoop" nillable="true"/>
<xs:complexType name="IfcEdgeLoop">
<xs:complexContent>
<xs:extension base="ifc:IfcLoop">
<xs:sequence>
<xs:element name="EdgeList">
<xs:complexType>
<xs:sequence>
<xs:element ref="ifc:IfcOrientedEdge" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute ref="ifc:itemType" fixed="ifc:IfcOrientedEdge"/>
<xs:attribute ref="ifc:cType" fixed="list"/>
<xs:attribute ref="ifc:arraySize" use="optional"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcEdgeLoop
SUBTYPE OF (IfcLoop);
EdgeList : LIST [1:?] OF IfcOrientedEdge;
DERIVE
Ne : IfcInteger := SIZEOF(EdgeList);
WHERE
IsClosed : (EdgeList[1].EdgeStart) :=: (EdgeList[Ne].EdgeEnd);
IsContinuous : IfcLoopHeadToTail(SELF);
END_ENTITY;

EXPRESS-G diagram

`

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