IFC 4.3.x development

6.3.3.4 IfcDiscreteAccessoryType

Change log

IFC4

additionsattributes PredefinedType
additionswhere_rulesCorrectPredefinedType

6.3.3.4.1 Semantic definitions at the entity

The element component type IfcDiscreteAccessoryType defines commonly shared information for occurrences of discrete accessorys. The set of shared information may include:

  • common properties with shared property sets
  • common representations
  • common materials
  • common composition of elements

It is used to define a discrete accessory type specification indicating the specific product information that is common to all occurrences of that product type. The IfcDiscreteAccessoryType may be declared within IfcProject or IfcProjectLibrary using IfcRelDeclares and may be exchanged with or without occurrences of the type. Occurrences of IfcDiscreteAccessoryType are represented by instances of IfcDiscreteAccessory.

HISTORY  New entity in IFC4.

Type Use Definition

The exact type information of the IfcDiscreteAccessoryType is given in the PredefinedType attribute, possibly in combination with the ElementType attribute inherited from IfcElementType. Standard ElementType designations are provided for guideline below. The list is not exhaustive and the list of definitions may be extended based on local agreements.

Corbels as separate components:

  • 'Hidden steel corbel': Corbel system made from steel components embedded into the master element.
  • 'Visible steel corbel': Corbel system made from steel components protruding from the master element.
  • 'Visible concrete corbel': Corbel system made as a separate precast concrete component added to the master element.

Connecting accessories, for example for sandwich wall panels:

  • 'Diagonal truss connector': A fixing device in truss form with diagonal cross bars holding two precast conrete panels together in a sandwich wall panel.
  • 'Ladder truss connector': A fixing device in truss form with straight cross bars in ladder form holding two precast conrete panels together in a sandwich wall panel.
  • 'Panel suspender': A straight fixing device holding two precast conrete panels together in a sandwich wall panel.

Electrical accessories for precast concrete elements:

  • 'Protective plug': Protective plug used in element for protecting electrical accessories during manufacturing, transportation and assembly.

Fixing parts:

  • 'Standard fixing plate': Standard fixing plate.
  • 'Edge fixing plate': Fixing plate attached to the edge of an element.
  • 'Corner fixing plate': Fixing plate attached to the corner of an element.
  • 'Slab fixing plate': Fixing plate for slabs.
  • 'Channel fixing': Fixing channels, often realized as cast-in channels.
  • 'Balcony hinge': Accessory supporting and fixing balconies.
  • 'Frame shoe': Fixing shoe for frames.
  • 'Thermo frame': Thermo frame.
  • 'Column shoe': Fixing shoe for columns.
  • 'Wall shoe': Fixing shoe for walls.
  • 'Fixing socket': Fixing socket.

Joint accessories:

  • 'Neoprene bearing plate': Rubber plate used as a bearing in, for example, joints between column corbels and beams.
  • 'Working joint reinforcement': Reinforcement accessory used in working joints.
  • 'Expansion joint reinforcement': Reinforcement accessory used in expansion joints.
  • 'Ribbed steel bar extension': Extension accessory made of a ribbed (reinforcement) bar used in joints.
  • 'Steel pin bolt': Pin bolt used to join together, for example, columns and beams.
  • 'Concrete dowel': Dowel pin used in joints.
  • 'Concrete groove': A groove made in a joint.
  • 'Steel plate': A steel plate used as an accessory in a joint.
  • 'Wire loop': A joint connector accessory made from a wire loop.
  • 'Steel loop': A joint connector accessory made from a steel bar loop.
  • 'Sealing strip': A strip sealing the joint.
  • 'Sealing compound': Sealing compound protecting and sealing the joint.

Lifting accessories:

  • 'Wire lifting hook': A lifting aid in the form of a wire loop.
  • 'Steel lifting hook': A lifting aid in the form of a steel bar loop.
  • 'Lifting socket': A lifting aid in the form of a socket.
  • 'Steel lifting anchor': A lifting aid in the form of a steel lifting anchor.
  • 'Lifting hole': A lifting aid in the form of a hole.

Accessories mainly used in the building services domain:

  • 'Antivibration' : An isolating device to prevent other elements to be effected by vibrations.
  • 'Drop rod' : A length of material providing a hanging support to a bracket. Note that a drop rod is considered to include nuts and washers required for securing.
  • 'Duct foot' : A base support used to receive a vertical pipe .
  • 'Framing' : A frame placed around a penetration to prevent scraping against the building surface or structure.
  • 'Grommet' : An element placed within a penetration that seals the penetration for a particular reason.
  • 'Rack' : A set of shelving for the purposes of storage that may be freestanding or bolted to a structure.
  • 'Safety part' : A part, typically installed in vertical shafts at each level, to ensure safety from falling when entering the shaft.
  • 'Sleeve' : A thin barrier placed between a penetration and a penetrating element.
  • 'Support section' : A section of material that is used as an intermediate support upon which multiple brackets can be mounted.

6.3.3.4.1 Attributes

# Attribute Type Description
IfcRoot
1 GlobalId IfcGloballyUniqueId Assignment of a globally unique identifier within the entire software world.
2 OwnerHistory OPTIONAL IfcOwnerHistory Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object,

> NOTE  only the last modification in stored - either as addition, deletion or modification.

> IFC4 CHANGE  The attribute has been changed to be OPTIONAL.
3 Name OPTIONAL IfcLabel Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.
4 Description OPTIONAL IfcText Optional description, provided for exchanging informative comments.
IfcObjectDefinition
HasAssignments SET [0:?] OF IfcRelAssigns FOR RelatedObjects Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.
Nests SET [0:1] OF IfcRelNests FOR RelatedObjects References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical strutures only).

> IFC4 CHANGE  The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition.
IsNestedBy SET [0:?] OF IfcRelNests FOR RelatingObject References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types).

> IFC4 CHANGE  The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition.
HasContext SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object.

> IFC4 CHANGE  The inverse attribute datatype has been added.
IsDecomposedBy SET [0:?] OF IfcRelAggregates FOR RelatingObject References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definitions can be aggregated by several other objects (occurrences or parts).

> IFC4 CHANGE  The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
Decomposes SET [0:1] OF IfcRelAggregates FOR RelatedObjects References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definitions can only be part of a single decomposition (to allow hierarchical strutures only).

> IFC4 CHANGE  The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
HasAssociations SET [0:?] OF IfcRelAssociates FOR RelatedObjects Reference to the relationship objects, that associates external references or other resource definitions to the object.. Examples are the association to library, documentation or classification.
IfcTypeObject
5 ApplicableOccurrenceOPTIONAL IfcIdentifier The attribute optionally defines the data type of the occurrence object, to which the assigned type object can relate. If not present, no instruction is given to which occurrence object the type object is applicable. The following conventions are used:

* The IFC entity name of the applicable occurrence using the IFC naming convention, CamelCase with IFC prefix

* It can be optionally followed by the predefined type after the separator "/" (forward slash), using uppercase

* If one type object is applicable to many occurrence objects, then those occurrence object names should be separate by comma "," forming a comma separated string.

> EXAMPLE Refering to a furniture as applicable occurrence entity would be expressed as 'IfcFurnishingElement', refering to a brace as applicable entity would be expressed as 'IfcMember/BRACE', refering to a wall and wall standard case would be expressed as 'IfcWall, IfcWallStandardCase'.
6 HasPropertySets OPTIONAL SET [1:?] OF IfcPropertySetDefinition Set ~~list~~ of unique property sets, that are associated with the object type and are common to all object occurrences referring to this object type.

> IFC2x3 CHANGE  The attribute aggregate type has been changed from LIST to SET.
Types SET [0:1] OF IfcRelDefinesByType FOR RelatingType Reference to the relationship IfcRelDefinedByType and thus to those occurrence objects, which are defined by this type.
IfcTypeProduct
7 RepresentationMaps OPTIONAL LIST [1:?] OF UNIQUE IfcRepresentationMap List of unique representation maps. Each representation map describes a block definition of the shape of the product style. By providing more than one representation map, a multi-view block definition can be given.
8 Tag OPTIONAL IfcLabel The tag (or label) identifier at the particular type of a product, e.g. the article number (like the EAN). It is the identifier at the specific level.
ReferencedBy SET [0:?] OF IfcRelAssignsToProduct FOR RelatingProductReference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product type.

> IFC4 CHANGE  New inverse relationship.
IfcElementType
9 ElementType OPTIONAL IfcLabel The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute 'PredefinedType' is set to USERDEFINED.
IfcElementComponentType
IfcDiscreteAccessoryType
10 PredefinedType IfcDiscreteAccessoryTypeEnum Subtype of discrete accessory

6.3.3.4.2 Entity inheritance

dot_inheritance IfcDiscreteAccessoryType IfcDiscreteAccessoryType IfcElementComponentType IfcElementComponentType IfcDiscreteAccessoryType->IfcElementComponentType IfcElementComponentType_children 8 more... IfcElementComponentType_children->IfcElementComponentType IfcElementType IfcElementType IfcElementComponentType->IfcElementType IfcElementType_children 7 more... IfcElementType_children->IfcElementType IfcTypeProduct IfcTypeProduct IfcElementType->IfcTypeProduct IfcTypeProduct_children 3 more... IfcTypeProduct_children->IfcTypeProduct IfcTypeObject IfcTypeObject IfcTypeProduct->IfcTypeObject IfcTypeProcess IfcTypeProcess IfcTypeProcess->IfcTypeObject IfcObjectDefinition IfcObjectDefinition IfcTypeObject->IfcObjectDefinition IfcTypeResource IfcTypeResource IfcTypeResource->IfcTypeObject IfcContext IfcContext IfcContext->IfcObjectDefinition IfcRoot IfcRoot IfcObjectDefinition->IfcRoot IfcObject IfcObject IfcObject->IfcObjectDefinition IfcPropertyDefinition IfcPropertyDefinition IfcPropertyDefinition->IfcRoot IfcRelationship IfcRelationship IfcRelationship->IfcRoot

6.3.3.4.3 Definitions applying to General Usage

6.3.3.4.3.1 Classification Association

Any object occurrence or object type can have a reference to a specific classification reference, i.e. to a particular facet within a classification system.

6.3.3.4.3.2 Identity

IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.

6.3.3.4.3.3 Product Type Shape

The RepresentationMaps define the type product shape and multiple geometric representations can be assigned. If a product occurrence is assigned to the type by using the IfcRelDefinesByType relationship, then these occurrences have to reference the representation maps. The reference is created by one or multiple IfcShapeRepresentation's having an IfcMappedItem as Items, that places the IfcRepresentationMap of the type product into the spatial contexts, i.e. by using an Cartesian transformation operator to transform the IfcRepresentationMap into the object coordinate system of the product occurrence.

Figure 136 illustrates an example of referencing a representation map by the shape representation of a product occurrence. Here the Cartesian transformation operator only uses translation, but no rotation, mirroring, or scaling.

representation map

Figure 136 — Product type geometry with single placement

Figure 137 illustrates an example of referencing a representation multiple times map by the shape representation of a product occurrence. Here the Cartesian transformation operator only uses translation, but no rotation, mirroring, or scaling. The different translation values determine the pattern of the multiple placement.

representation map

Figure 137 — Product type geometry with multiple placement

6.3.3.4.3.4 Revision Control

Ownership, history, and merge state is captured using IfcOwnerHistory.

6.3.3.4.4 Formal representations

ENTITY IfcDiscreteAccessoryType
 SUBTYPE OF (IfcElementComponentType);
	PredefinedType : IfcDiscreteAccessoryTypeEnum;
 WHERE
	CorrectPredefinedType : (PredefinedType <> IfcDiscreteAccessoryTypeEnum.USERDEFINED) OR
((PredefinedType = IfcDiscreteAccessoryTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcElementType.ElementType));
END_ENTITY;