IfcUnitAssignment

BACnet MVD

#### IfcUnitAssignment

Natural language names

| Einheit - Zuweisung
| Unit Assignment
| Assignation d'unité

##### Semantic definitions at the entity

Entity definition

IfcUnitAssignment indicates a set of units which may be assigned. Within an IfcUnitAssigment each unit definition shall be unique; that is, there shall be no redundant unit definitions for the same unit type such as length unit or area unit. For currencies, there shall be only a single IfcMonetaryUnit within an IfcUnitAssignment.

> NOTE A IfcProject has a unit assignment which establishes a set of units which will be used globally within the project, if not otherwise defined. Other objects may have local unit assignments if there is a requirement for them to make use of units which do not fall within the project unit assignment.

> HISTORY New entity in IFC1.5.1.

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
1 | Units | IfcUnit | S[1:?] | Units to be included within a unit assignment. |  | X

Formal Propositions

Rule | Description
--- | ---
WR01 | Checks that the set of globally assigned units has each unit type (either of type IfcNamedUnit,IfcDerivedUnit, or IfcMonetaryUnit) defined only once.

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
IfcUnitAssignment
1 | Units | IfcUnit | S[1:?] | Units to be included within a unit assignment. |  | X

##### Definitions applying to BACnet View

Instance diagram

#####

Concept usage

Unit Assignment

The Unit Assignment concept applies to this entity.

mvdXML Specification
`<?xml version="1.0"?>
<ConceptRoot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" uuid="be435871-23f0-4367-a576-9cbf8a4832fd" name="IfcUnitAssignment" status="sample" applicableRootEntity="IfcUnitAssignment">
<Concepts>
<Concept uuid="17e5c482-6747-4a6b-9951-0fbdb2301f8c" name="Unit Assignment" status="sample" override="false">
<Template ref="e5637fde-2b39-4330-b99f-84b94978ace6" />
</Concept>
</Concepts>
</ConceptRoot>
`
Concept inheritance

# | Concept | Template | Model View
--- | --- | --- | ---
IfcUnitAssignment
| Unit Assignment | Unit Assignment | BACnet View

##### Examples

- Basic unit declaration

##### Formal representations

XML Specification
`<xs:element name="IfcUnitAssignment" type="ifc:IfcUnitAssignment" substitutionGroup="ifc:Entity" nillable="true"/>
<xs:complexType name="IfcUnitAssignment">
<xs:complexContent>
<xs:extension base="ifc:Entity">
<xs:sequence>
<xs:element name="Units">
<xs:complexType>
<xs:group ref="ifc:IfcUnit" maxOccurs="unbounded"/>
<xs:attribute ref="ifc:itemType" fixed="ifc:IfcUnit"/>
<xs:attribute ref="ifc:cType" fixed="set"/>
<xs:attribute ref="ifc:arraySize" use="optional"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcUnitAssignment;
Units : SET [1:?] OF IfcUnit;
WHERE
WR01 : IfcCorrectUnitAssignment(Units);
END_ENTITY;

EXPRESS-G diagram

`

References: IfcContext

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