A request is the act or instance of asking for something, such as a request for information, bid submission, or performance of work. Requests may take many forms depending on the need including fault reports for maintenance, requests for small works, and purchase requests (where these are to be made through a help desk or buying function).
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The IfcActor defines all actors or human agents involved in a project during its full life cycle. It facilitates the use of person and organization definitions in the resource part of the IFC object model. This includes name, address, telecommunication addresses, and roles.
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This entity indicates a role which is performed by an actor, either a person, an organization or a person related to an organization.

The alignment defines three interconnected concepts:... more

An IfcAlignmentCant is a lateral inclination profile defined along the horizontal alignment. All points defined in this profile have two coordinate values. The first value is the distance along the horizontal alignment and the second value is the height relative to the projection of the point along vertical alignment.

This class represents an individual segment (or sequence) that defines whole cant alignment. The cant alignment is defined by ordered segments that connect end-to-start. The points defined in a cant alignment segment are defined in a plane with x = distance along horizontal alignment and y = height relative to projected points in vertical alignment. The following cant segment types are defined in the IfcAlignmentCantSegmentTypeEnum enumeration:... more

An IfcAlignmentHorizontal is a linear reference projected onto the horizontal x/y plane. Points along a horizontal alignment have two coordinate values, x and y in the local Cartesian engineering system.

Individual segment along the IfcAlignmentHorizontal, being defined in the x/y coordinate space. Each single horizontal alignment segment has an optional associated segment definition. The placement of IfcAlignmentHorizontalSegment and the IfcCurveSegment StartPlacement correspond to each other.
The following information can be calculated (and is therefore not exchanged explicitly to avoid redundancy and inconsistencies):... more

An abstract entity defining common information about horizontal, vertical and cant alignment segments.

An IfcAlignmentSegment is a segment of an IfcAlignment where either the vertical or horizontal direction or cant (in the case of track design) obey a unique mathematical description as a function of the horizontal projection segment length of the alignment.

An IfcAlignmentVertical is a height profile along the horizontal alignment. Points along a vertical alignment have two coordinate values. The first value is the distance along the horizontal alignment, the second value is the height according to the project engineering coordinate system. Based on the context of the project, they are georeferenced and the height value is convertible into orthogonal height above/below the vertical datum.

Individual segment along the IfcAlignmentVertical is defined in the distance-along/z coordinate space. The vertical alignment is defined by segments that connects end-to-start. The vertical alignment curve geometry is defined in a plane with x = distance along horizontal, the y = height (or elevation). The transition at the segment connection is not enforced to be tangential, The IfcSegment Transition enumeration specifies the type of transition explicitly. The following vertical segment types are defined in the :... more

An annotation is an information element within the geometric (and spatial) context of a project, that adds a note or meaning to the objects which constitutes the project model. Annotations include additional points, curves, text, dimensioning, hatching and other forms of graphical notes. It also includes virtual or symbolic representations of additional model components, not representing products or spatial structures, such as event elements, survey points, contour lines or similar.
If available, the annotation should be related to the spatial context of the project, by containing the annotation within the appropriate level of the building structure (site, facility, facility part... more

An asset is a uniquely identifiable grouping of elements acting as a single entity that has a financial value or that can be operated on as a single unit.
An asset is generally the level of granularity at which maintenance operations are undertaken. An asset is a group that can contain one or more elements. Whilst the financial value of a component or element can be defined, financial value is also defined for accounting purposes at the level of the asset.
There are a number of actors that can be associated with an asset, each actor having a role. Actors... more

An IfcBeam is a horizontal, or nearly horizontal, structural member that is capable of withstanding load primarily by resisting bending. It represents such a member from an architectural point of view. It is not required to be load bearing. There are two main representations for beam occurrences:... more

Type of building element that is usually used to transmit loads from superstructure to substructure, and usually allowing movement (displacement or rotation) in one or more degrees of freedom. It is typically a mechanical component procured as a whole and installed on site, but in simple cases it may be built on site (composed of other building elements, element components, etc.).
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Representation of the concept of a linear geological and geotechnical model, usually an interpretation but sometimes created direct from ground penetrating measurement. The assembly may contain one of more strata and other elements such as capping and lining. The contained subtypes of IfcGeotechnicalStratum will have shape representations made from straight or bent tubes reflecting the bore diameter, or discs if a 'Yabuki' top surface model is being used.

A building represents a structure that provides shelter for its occupants or contents and stands in one place. The building also provides a basic element within the spatial structure hierarchy for the components of a building project (together with site, storey, and space). A building is (if specified) associated to a site. The site can include a collection of buildings that are organized as a building complex. A building can be decomposed in parts to define a building sections:... more

IfcBuildingElementPart represents major components as subordinate parts of a building element. Typical usage examples include precast concrete sandwich walls, where the layers can have different geometry representations. In this case the layered material representation does not sufficiently describe the element. Each layer is represented by an own instance of the IfcBuildingElementPart with its own geometry description.
The kind of building element part is further specified by a corresponding instance of IfcBuildingElementPartType, referred to by IfcRelDefinesByType.
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The IfcBuildingElementProxy is a proxy definition that provides the same functionality as subtypes of IfcBuildingElement, but without having a predefined meaning of the special type of building element, it represents. Proxies can also be used as spatial place holders or provisions, that are later replaced by special types of elements.
One use of the proxy object is a provision for voids, i.e. where a particular volume of space is requested by an engineering function that might later be accepted or rejected. If accepted it is transformed into a void within a building element, like a wall opening, or a slab... more

A building system is a group by which building elements are grouped according to a common function within the facility. The group IfcBuildingSystem defines the occurrence of a specialized system for use within the context of a building and finishing fabric. Important functionalities for the description of a building system are derived from supertypes:
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The built element comprises all elements that are primarily part of the construction of a built facility, i.e., its structural and space separating system. Built elements are all physically existent and tangible things.
This IfcBuiltElement is a generalization of all elements that are major functional parts of the structural or space separation system of a built facility. Typical examples of IfcBuiltElement's are (among others):... more

A built system is a group by which built elements are grouped according to a common function within the facility. The group IfcBuiltSystem defines the occurrence of a specialized system for use within the context of a facilities physical or finishing fabric. Important functionalities for the description of a built system are derived from supertypes:
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Chimneys are typically vertical, or as near as vertical, parts of the construction of a building and part of the building fabric.... more

An IfcCivilElement is a generalization of all elements within a civil engineering works that cannot be represented as BuildingElements, DistributionElements or GeographicElements. Depending on the context of the construction project, included building work, such as buildings or factories, are represented as a collection of IfcBuildingElement's, distribution systems, such as piping or drainage, are represented as a collection of IfcDistributionElement's, and other geographic elements, such as trees, light posts, traffic signs etc. are represented as IfcGeographicElement's.
Civil elements are typically horizontally organized using a spatial structure expressed by spatial zones, therefore IfcCivilElement is spatially contained by default within an IfcSpatialZone.
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A clothoid is a planar curve in the form of a spiral. This curve has the property that the curvature varies linearly with the arc length.... more

The IfcColourRgbList defines an ordered collection of RGB colour values. Each colour value is a fixed list of three colour components (red, green, blue). The attribute ColourList is a two-dimensional list, where:
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The colour specification entity contains a direct colour definition. Colour component values refer directly to a specific colour space.

An IfcColumn is a vertical structural member which often is aligned with a structural grid intersection. It represents a vertical, or nearly vertical, structural member that transmits, through compression, the weight of the structure above to other structural elements below. It represents such a member from an architectural point of view. It is not required to be load bearing.
There are two main representations for column occurrences:... more

IfcComplexProperty is used to define complex properties to be handled completely within a property set. The included set of properties may be a mixed or consistent collection of IfcProperty subtypes. This enables the definition of a set of properties to be included as a single 'property' entry in an IfcPropertySet. The definition of such an IfcComplexProperty can be reused in many different IfcPropertySet's.

The IfcComplexPropertyTemplate defines the template for all complex properties, either the IfcComplexProperty's or the IfcPhysicalComplexQuantity's. The individual complex property templates are interpreted according to their Name attribute and optional UsageName attribute.

An IfcCompositeCurve is a continuous curve composed of curve segments that are joined end-to-end. The parameterization of the composite curve is an accumulation of the parametric ranges of the referenced bounded curves.... more

IfcContext is the generalization of a project context in which objects, type objects, property sets, and properties are defined. The IfcProject as subtype of IfcContext provides the context for all information on a construction project, it may include one or several IfcProjectLibrary's as subtype of IfcContext to register the included libraries for the project. A library of products that is referenced is declared within the IfcProjectLibrary as the context of that library.
A context is declared by the IfcRelDeclares object that refers to the corresponding objects within the context. More specific relationships are introduced at the level of subtypes.

IfcControl is the abstract generalization of all concepts that control or constrain the utilization of products, processes, or resources in general. It can be seen as a regulation, cost schedule, request or order, or other requirements applied to a product, process or resource whose requirements and provisions must be fulfilled.... more

This class represents a type of spiral curve for which the curvature change is dependent on the cosine function.

An IfcCostItem describes a cost or financial value together with descriptive information that describes its context in a form that enables it to be used within a cost schedule. An IfcCostItem can be used to represent the cost of goods and services, the execution of works by a process, lifecycle cost and more.
Each instance of IfcCostItem may have a name and a description. Depending on the use for which the cost is intended, these values should be asserted on the basis of agreement. For instance, the Name attribute could be used to provide a common value that enables distinct... more

An IfcCostSchedule brings together instances of IfcCostItem either for the purpose of identifying purely cost information as in an estimate for constructions costs or for including cost information within another presentation form such as a work order.
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A built element whose length greatly exceeds its thickness and often also its width, usually of a single material laid on site on top of another horizontal or nearly horizontal built element. A course is distinctive from a earthworks element in that a course is a graded granular (which can be bound or unbound) material that is generally processed in some fashion, where as earthworks elements are soil earthen-based structure that can be formed by removal and transport of general ground material. Structurally a course does not have capacity to carry loads over open span, or to be removed or... more

A covering is an element which covers some part of another element and is fully dependent on that other element. The IfcCovering defines the occurrence of a covering type, that (if specified) is expressed by the IfcCoveringType.
Coverings can be assigned to:... more

A curtain wall is an exterior wall of a building which is an assembly of components, hung from the edge of the floor/roof structure rather than bearing on a floor. Curtain wall is represented as a building element assembly and implemented as a subtype of IfcBuildingElement that uses an IfcRelAggregates relationship.
The geometric representation of IfcCurtainWall is defined using the following multiple shape representations for its definition:... more

IfcCurve is a curve in two-dimensional or three-dimensional space. It includes definitions for bounded and unbounded curves.

The IfcCurveBoundedPlane is a parametric planar surface with curved boundaries. The bounded plane is defined to be the portion of the basis surface in the direction of N x T from any point on the boundary, where N is the surface normal and T the boundary curve tangent vector at this point. The defined region will be arcwise connected.
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IfcCurveBoundedSurface is a parametric surface with boundaries defined by p-curves, that is, a curve which lies on the basis of a surface and is defined in the parameter space of that surface. The p-curve is a special type of a composite curve segment and is used only to bound a surface.,The curve bounded surface is a parametric surface with curved boundaries defined by one or more boundary curves. One of the boundary curves may be the outer boundary; any number of inner boundaries is permissible. The region of the curve bounded surface in the basis surface is defined to be... more

This class represents a type of segment positioned along a curve cutting a segment from the parent curve. The positioning curve (StartPlacement.PlacementMeasuredAlong) does not necessarily correspond with the ParentCurve.

An IfcCurveStyle provides the style table for presentation information assigned to geometric curves. The style is defined by a color, a font and a width. The IfcCurveStyle defines curve patterns as model patterns, that is, the distance between visible and invisible segments of curve patterns that are given in model space dimensions (that have to be scaled using the target plot scale).

This class represents a curve style font that combines several curve style font pattern entities into a more complex pattern. The resulting pattern is repeated along the curve.

The IfcCurveStyleFontAndScaling allows for the reuse of the same curve style definition in several sizes. The definition of the CurveFontScale is the scaling of a base curve style pattern to be used as a new or derived curve style pattern.

A curve style font pattern is a pair of visible and invisible curve segment length measures in presentation area units.

Deep foundation is a type of foundation that transfers loads deeper than a shallow foundation below the soft soils not capable of bearing the above structure. Depending on the soil strength it might have to reach down to the rock layer.
Deep foundation is a new supertype incorporating the existing IfcPile and the new IfcCaissonFoundation.
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A discrete accessory is a representation of different kinds of accessories included in or added to elements.... more

A distribution circuit is a partition of a distribution system that is conditionally switched such as an electrical circuit.
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This IfcDistributionElement is a generalization of all elements that participate in a distribution system. Typical examples of IfcDistributionElement's are:... more

A distribution port is an inlet or outlet of a product through which a particular substance can flow.
Distribution ports are used for passage of solid, liquid, or gas substances, as well as electricity for power or communications. Flow segments (pipes, ducts, cables) can be used to connect ports across products. Distribution ports are defined by system type and flow direction such that for two ports to be connected, they must share the same system type and have opposite flow directions (one side being a SOURCE and the other being a SINK). Ports are similar to openings in that they... more

A distribution system is a network designed to receive, store, maintain, distribute, or control the flow of a distribution media. A common example is a heating hot water system that consists of a pump, a tank, and an interconnected piping system for distributing hot water to terminals.
The group IfcDistributionSystem defines the occurrence of a specialized system for use within the context of building services or utilities for built facilities. Important functionalities for the description of a distribution system are derived from existing IFC entities:... more

The door is a built element that is predominately used to provide controlled access for people, goods, animals and vehicles. It includes constructions with hinged, pivoted, sliding, and additionally revolving and folding operations. A door can:... more

The door lining is the frame which enables the door leaf to be fixed in position. The door lining is used to hang the door leaf. The parameters of the door lining define the geometrically relevant parameter of the lining.
The IfcDoorLiningProperties are included in the list of properties of IfcDoorType.HasPropertySets. More information about the door lining can be included in the same list of the IfcDoorTyype using another IfcPropertySet for dynamic extensions. The IfcDoorLiningProperties does not hold its own geometric representation. However it defines parameters which can be used to create the shape of the door type (which is... more

A door panel is normally a door leaf that opens to allow people or goods to pass. The parameters of the door panel define the geometrically relevant parameter of the panel. The IfcDoorPanelProperties are used to parametrically describe the shape and operation of door panels. The parametric definition can be added solely or additionally to the explicit shape representation of the door.
The parameters of the IfcDoorPanelProperties do not hold a geometric representation. Instead they define a standard door panel, including (if given) a proportional width to define non-uniform double swing (or sliding, or folding) doors. The outer boundary of... more

The resulting void from modification of existing terrain or road structure by excavation or by other means of removing material.... more

A type of built element created by earthwork activities to build sub-grade, to raise the level of the ground in general or reinforce or stabilize soil by some mechanical or chemical method.

An element is a generalization of all components that make up an AEC product. Elements are physically existent objects, although they might be void elements, such as holes. Elements can be either assembled on site or pre-manufactured and built in on site.... more

The IfcElementAssembly represents complex element assemblies aggregated from several elements, such as discrete elements, building elements, or other elements. The geometry of an IfcElementAssembly is generally formed from its components, in which case it does not need to have an explicit geometric representation. In some cases it can be useful to also expose an own explicit representation of the aggregate.
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An element component is a representation for minor items included in, added to or connecting to or between elements, which usually are not of interest from the overall building structure viewpoint. However, these small parts may have vital and load carrying functions within the construction. These items do not provide any actual space boundaries. Typical examples of _IfcElementComponent_s include different kinds of fasteners and various accessories.
It is often desirable to model a number of same-shaped element components by means of a single occurrence object, e.g. several bolts within a connection or a row of reinforcement elements. In this IFC... more

An IfcElementQuantity defines a set of derived measures of an element's physical property. Elements could be spatial structure elements (like buildings, storeys, or spaces) or building elements (like walls, slabs, finishes). The IfcElementQuantity gets assigned to the element by using the IfcRelDefinesByProperties relationship.
The IfcElementQuantity can have the following subtypes of IfcPhysicalQuantity within its SET of Quantities, which count for the basis measure types used:... more

IfcEvent is used to capture information about particular things that happen or that may happen. Particularly used in work plans (or process maps) they identify e.g. a point at which a message containing information may be issued or at which a rule or constraint is invoked.
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The IfcExtendedProperties is an abstract supertype of all extensible property collections that are applicable to certain characterized entities. Instantiable subtypes of IfcExtendedProperties assign the property collection to a particular characterized entity.

Representations of fixing parts which are used as fasteners to connect or join elements with other elements. Excluded are mechanical fasteners which are modeled by a separate entity (IfcMechanicalFastener).
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A feature element is a generalization of all existence-dependent elements which modify the shape and appearance of the associated master element. The IfcFeatureElement offers the ability to handle shape modifiers as semantic objects within the IFC object model.
In contrary to the aggregation, as used in IfcElementAssembly, that defines the aggregate as a container element, that has equally treated parts, the feature concept introduced by IfcFeatureElement defines the master element with subordinate parts as additions, or with voids or cut-outs as subtractions.
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A feature element addition is a specialization of the general feature element, that represents an existence dependent element which modifies the shape and appearance of the associated master element. The IfcFeatureElementAddition offers the ability to handle shape modifiers as semantic objects within the IFC object model that add to the shape of the master element.
The IfcFeatureElementAddition is associated to its master element by virtue of the objectified relationship IfcRelProjectsElement. This relationship implies a Boolean 'union' operation between the shape of the master element and the shape of the addition feature. The local placement for IfcFeatureElementAddition is defined in its... more

The IfcFeatureElementSubtraction is specialization of the general feature element, that represents an existence dependent elements which modifies the shape and appearance of the associated master element. The IfcFeatureElementSubtraction offers the ability to handle shape modifiers as semantic objects within the IFC object model that subtract from the shape of the master element.
The voiding relationship between a master element and a subtraction feature is geometrically resolved by a Boolean difference operation. The local placement for IfcFeatureElementSubtraction is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric... more

A footing is a part of the foundation of a structure that spreads and transmits the load to the soil. A footing is also characterized as shallow foundation, where the loads are transferred to the ground near the surface.
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A furnishing element is a generalization of all furniture related objects. Furnishing objects can be:... more

Furniture defines complete furnishings such as a table, desk, chair, or cabinet, which may or may not be permanently attached to a building structure. Occurrences of furniture that are built in (where the property Pset_FurnitureTypeCommon.IsBuiltIn is asserted to be TRUE) should have their connection relationship with a building element occurrence defined through the IfcRelConnectsElements relationship.
The Object Typing concept template applies to this entity as shown in the table below. ... more

An IfcGeographicElement is a generalization of all elements within a geographical landscape. It includes occurrences of typical geographical elements, often referred to as features, such as trees or terrain. Common type information behind several occurrences of IfcGeographicElement is provided by the IfcGeographicElementType.
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This definition is representation of the concept of a volumetric geological and geotechnical model, usually an interpretation but sometimes created direct from ground penetrating measurement. The contained subtypes of IfcGeotechnicalStratum have shape representations made from polyhedron or surfaces if a 'Yabuki' top surface model is used.

This definition is representation of the concept of a sectional planar geological and geotechnical model, usually an interpretation but sometimes created direct from ground penetrating measurement. The assembly can contain one of more strata and anthropic elements. The contained subtypes of IfcGeotechnicalStratum have shape representations made from polygons reflecting the visible section or polylines if a 'Yabuki' top surface model is used.

This definition is representation of the abstract concept of a geological and geotechnical model, usually an interpretation but sometimes created direct from ground penetrating measurement. Such assemblies include IfcGeotechnicalStratum entity types and can include other entity types such as IfcPile, IfcSlab or IfcSensor to represent the capping, lining or logging equipment. Geological construction hazards such as IfcBorehole or IfcGeoSlice can be associated to any IfcGeotechnicalAssembly or IfcGeotechnicalStratum.
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Abstract supertype for geotechnical entities.

This definition is a representation of the concept of an identified discrete almost homogeneous geological feature with either an irregular solid or 'Yabuki' top surface shape or a regular voxel cubic shape. A stratum is represented as a discrete entity, specialized (sub-typed) from IfcElement. A stratum can be broken down into smaller entities if properties vary across the stratum or alternatively properties can be described with bounded numeric ranges. A stratum can carry information about the physical form and its interpretation as a Geological Item (GML). The shape representations used should correspond to the sub-type of IfcGeotechnicalAssembly in which it... more

Gradient curve is a type of 3D curve representation that is based on its 2D projection (BaseCurve) and a height defined by its gradient segments which can be derived from a function that retrieves it from the segment start height, its placement and the ParentCurve instance and the type of the ParentCurve. The parametrization of the gradient curve is based on the underlying segments of its BaseCurve. The value of the parameter equals the parameter value of BaseCurve.

IfcGroup is an generalization of any arbitrary group. A group is a logical collection of objects. It does not have its own position, nor can it hold its own shape representation. Therefore a group is an aggregation under some non-geometrical / topological grouping aspects.
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A impact protection device is a component used to protect other built elements from kinetic damage. impact protection devices currently come in 3 different varieties:
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The IfcIndexedColourMap provides the assignment of colour information to individual faces. It is used for colouring faces of tessellated face sets.... more

An inventory is a list of items within an enterprise. Various types of inventory can be included. These are identified by the range of values within the inventory type enumeration which includes space, asset, and furniture. User defined inventories can also be defined for lists of particular types of element such as may be required in operating and maintenance instructions. Such inventories should be constrained to contain a list of elements of a restricted type.
There are a number of actors that can be associated with an inventory, each actor having a role. Actors within the scope of the project... more

This entity instance represents a border of stone, concrete or other rigid material formed at the edge of the carriageway or footway.

A generalization of all linear elements that are parts of an alignment.

A mechanical fasteners connecting building elements or parts mechanically. A single instance of this class can represent one or many of actual mechanical fasteners, for example an array of bolts or a row of nails.
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An IfcMember is a structural member designed to carry loads between or beyond points of support. It is not required to be load bearing. The orientation of the member (being horizontal, vertical or sloped) is not relevant to its definition (in contrary to IfcBeam and IfcColumn). An IfcMember represents a linear structural element from an architectural or structural modeling point of view and is used if it cannot be expressed more specifically as either an IfcBeam or an IfcColumn.
There are two main representations for member occurrences:... more

A mooring device is an active or passive built element who's primary function is to participate in the mooring of a vessel, this could be in the form of a bollard used as an attachment point for lines or active equipment such as quick release hooks.
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A navigation element is an active or passive built element who's primary function is to provide navigational instructions and warnings to vessels, this could be in the form of a floating buoy, a fixed beacon, etc. Navigation elements can aggregate other components and elements to form the entire structure.
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An IfcObject is the generalization of any semantically treated thing or process. Objects are things as they appear - i.e. occurrences.
Objects are independent pieces of information that might contain or reference other pieces of information. There are several relationships in which objects can be involved:... more

An IfcObjectDefinition is the generalization of any semantically treated thing or process, either being a type or an occurrences. Object definitions can be named, using the inherited Name attribute, which should be a user recognizable label for the object occurrence. Further explanations to the object can be given using the inherited Description attribute. A context is a specific kind of object definition as it provides the project or library context in which object types and object occurrences are defined.
Objects are independent pieces of information that might contain or reference other pieces of information. There are four essential kinds of... more

An occupant is a type of actor that defines the form of occupancy of a property. The principal purpose of IfcOccupant is to determine the nature of occupancy of a property for a particular actor. All characteristics relating to the actor (name and organization details) are inherited from the IfcActor entity.
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The opening element stands for opening, recess or chase, all reflecting voids. It represents a void within any element that has physical manifestation. Openings can be inserted into walls, slabs, beams, columns, or other elements. There are two different types of opening elements. The attribute PredefinedType should be used to capture the differences:... more

The standard opening, IfcOpeningStandardCase, defines an opening with certain constraints for the dimension parameters, position within the voided element, and with certain constraints for the geometric representation. The IfcOpeningStandardCase handles all cases of openings, that:
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Type of built element in a road or other paved area to provide an even surface sustaining loads from vehicles or pedestrians, usually comprising several courses.
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IfcPerformanceHistory is used to document the actual performance of an occurrence instance over time. It includes machine-measured data from building automation systems and human-specified data such as task and resource usage. The data may represent actual conditions, predictions, or simulations.
The realtime data tracked by performance history takes the form of property sets where all properties are based on time series. Unlike design-based data at occurrences and types, performance-driven data is time-sensitive and may change in realtime by some measurement device. Data may be captured at irregular intervals such as when values change beyond established thresholds, or at regular intervals... more

This entity is a description of a panel within a door or window (as fillers for opening) which allows for air flow. It is given by its properties (IfcPermeableCoveringProperties). A permeable covering is a casement, such as a component, fixed or opening, consisting essentially of a frame and the infilling. The infilling is normally a grill, a louver or a screen. The way of operation is defined in the operation type.
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A permit is a permission to perform work in places and on artifacts where regulatory, security or other access restrictions apply.
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This instance represents trees, shrubs, herbs, grasses, ferns, and mosses.

An IfcPlate is a planar and often flat part with constant thickness. A plate can carry loads between or beyond points of support, or provide stiffening. The location of the plate (being horizontal, vertical or sloped) is not relevant to its definition.
Plates are normally made of steel, other metallic material, or by glass panels. However the definition of IfcPlate is material independent and specific material information is handled by using IfcAssociatesMaterial to assign a material specification to the IfcPlate.
Plates are often add-on parts. This is represented by the IfcRelAggregates decomposition mechanism used to aggregate parts, such as IfcPlate,... more

A polynomial curve is a curve that can be parametrized by polynomial functions of R[x].

A port provides the means for an element to connect to other elements.
An IfcPort is associated with an IfcElement, it belongs to through the objectified relationship IfcRelNests if such port is fixed, or IfcRelConnectsPortToElement if such port is dynamically attached. Exactly two ports, belonging to two different elements, are connected with each other through the objectified relationship IfcRelConnectsPorts.
An instance of IfcElement may have one or more points at which it connects to other instances of IfcElement. An instance of IfcPort is located at a point where a connection can occur. The location of the port is determined in... more

This abstract entity definition is used for positioning and annotating elements that are used to position other elements relatively.... more

A predefined item is a qualified name given to a style or font which is determined within the data exchange specification by convention on using the Name attribute value (in contrary to externally defined items, which are agreed by an external source).
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The IfcPreDefinedProperties is an abstract supertype of all predefined property collections that have explicit attributes, each representing a property. Instantiable subtypes are assigned to specific characterized entities.

IfcPreDefinedPropertySet is a generalization of all statically defined property sets that are assigned to an object or type object. The statically or predefined property sets are entities with a fixed list of attributes having particular defined data types.
Property sets are related to other objects by using the relationship object that refers to the corresponding object:... more

The IfcPresentationItem is the abstract supertype of all entities used for presentation appearance definitions.

The IfcPresentationStyle is an abstract generalization of style table for presentation information assigned to geometric representation items. It includes styles for curves, areas, surfaces, and text. Style information may include colour, hatching, rendering, and text fonts. The different styles may include length measures (directly as a length measure with inferred unit, or indirectly as a ratio in relation to another length measure). They may apply to curve pattern, hatch line distances, text spacing and font sizes.

An IfcProcedure is a logical set of actions to be taken in response to an event or to cause an event to occur.
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IfcProcess is defined as one individual activity or event, that is ordered in time, that has sequence relationships with other processes, which transforms input in output, and may connect to other other processes through input output relationships. An IfcProcess can be an activity (or task), or an event. It takes usually place in building construction with the intent of designing, costing, acquiring, constructing, or maintaining products or other and similar tasks or procedures. The next image illustrates process relationships.

Process information relates to other objects by establishing the following relationships:... more

The IfcProduct is an abstract representation of any object that relates to a geometric or spatial context. An IfcProduct occurs at a specific location in space if it has a geometric representation assigned. It can be placed relatively to other products, but ultimately relative to the project coordinate system. The ObjectPlacement attribute establishes the coordinate system in which all points and directions used by the geometric representation items under Representation are founded. The Representation is provided by an IfcProductDefinitionShape being either a geometric shape representation, or a topology representation (with or without underlying geometry of the topological items).
Products include... more

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IfcProject represents processes in design, engineering, construction, or maintenance activities performed for a product. The project forms the context for exchangeable information and it may optionally represent a construction project. The main aim of IfcProject's in an exchange structure is to provide the root instance and the context for other information items.
The context related to the project:... more

A project order is a directive to purchase products and/or perform work, such as for construction or facilities management.
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The projection element is a specialization of the general feature element to represent projections applied to building elements. It represents a solid attached to any element that has physical manifestation. An IfcProjectionElement has to be linked to a element (all subtypes of IfcElement) by using the IfcRelProjectsElement relationship. Its existence depends on the existence of the master element. The relationship implies a Boolean union operation between the volume of the projection element and the volume of the element.
The IfcProjectionElement does not participate in the containment relationship, i.e. it is not linked directly to the spatial structure of the project.... more

IfcProperty is an abstract generalization for all types of properties that can be associated with IFC objects through the property set mechanism.
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The IfcPropertyAbstraction is an abstract supertype of all property-related entities defined as dependent resource entities within the specification. It may have an external reference to a dictionary or library that provides additional information about its definition. Instantiable subtypes have property name, value and other instance information.

This class defines a property object which has a maximum of two (numeric or descriptive) values assigned. The first value specifies the upper bound and the second value specifies the lower bound. It defines a property - value bound (min-max) combination for which the property Name, optional Description,  optional UpperBoundValuewith measure type, optional LowerBoundValuewith measure type, and optional Unitis specified. A SetPointValueattribute can be provided in addition to the upper and lower bound values for operational value setting.

IfcPropertyDefinition defines the generalization of all characteristics (i.e. a grouping of individual properties), that can be assigned to objects. Currently, subtypes of IfcPropertyDefinition include property set occurrences, property set templates and property templates.
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An IfcPropertyDependencyRelationship describes an identified dependency between the value of one property and that of another. The determination of value according to the dependency is required to be performed by an application that can then use the Expression attribute to flag the form of the dependency.
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IfcPropertyEnumeratedValue defines a property object which has a value assigned that is chosen from an enumeration. The defined property is a value combination for which the property Name, an optional Description,  optional EnumerationValues with measure type and optionally Unit is specified.

IfcPropertyEnumeration is a collection of simple or measure values that define a prescribed set of alternatives from which 'enumeration values' are selected. This enables inclusion of enumeration values in property sets. IfcPropertyEnumeration provides a name for the enumeration as well as a list of unique (numeric or descriptive) values (that may have a measure type assigned). The entity defines the list of potential enumerators to be exchanged together (or separately) with properties of type IfcPropertyEnumeratedValue that selects their actual property values from this enumeration.
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An IfcPropertyListValue defines a property that has several (numeric or descriptive) values assigned, these values are given by an ordered list.  It defines a property - list value combination for which the property Name, an optional Description,  the optional ListValues with measure type and optionally an Unit are specified. An IfcPropertyListValue is an ordered list of values. All list members must be have the same type.... more

The IfcPropertyReferenceValue allows a property value to have the same type as a resource level entity. The applicable entities that can be used as value references are given by the IfcObjectReferenceSelect.
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The IfcPropertySet contains properties within a property tree. These properties are interpreted according to their name attribute. Property sets applicable to certain objects are listed in the object specification. The specification supposes usage of the naming convention "Pset_Xxx". Such naming convention is applied to the property sets that are defined as part of this specification and be used as the value of the Name attribute.
IfcPropertySet can be assigned to object occurrences and object types. An IfcPropertySet assigned to an object type is shared among all occurrences of the same object type.
Property sets are related to other objects by... more

IfcPropertySetDefinition is a generalization of all individual property sets that can be assigned to an object or type object. The property set definition can be either:... more

IfcPropertySetTemplate defines the template for all dynamically extensible property sets represented by IfcPropertySet. The property set template is a container of property templates within a property tree. The individual property templates are interpreted according to their Name attribute and will have no values assigned. Property set templates can form part of a property library used and declared within a project. Depending on the TemplateType the IfcPropertySetTemplate defines a template for:... more

The property with a single value IfcPropertySingleValue defines a property object which has a single (numeric or descriptive) value assigned. It defines a property - single value combination for which the property Name, an optional Description, and an optional NominalValue with measure type is provided. In addition, the default unit as specified within the project unit context can be overridden by assigning an Unit.
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IfcPropertyTableValue is a property with a value range defined by a property object which has two lists of (numeric or descriptive) values assigned. The values specify a table with two columns. The defining values provide the first column and establish the scope for the defined values (the second column). An optional Expression attribute may give the equation used for deriving the range value, which is for information purposes only.
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IfcPropertyTemplateDefinition is a generalization of all property and property set templates. Templates define the collection, types, names, applicable measure types and units of individual properties used in a project. The property template definition can be:
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IfcProxy is intended to be a kind of a container for wrapping objects which are defined by associated properties, which may or may not have a geometric representation and placement in space. A proxy can have a semantic meaning, defined by the Name attribute, and property definitions, attached through the property assignment relationship, which definition can be outside of the definitions given by the current release of IFC.
The ProxyType can give an indication to which high level semantic breakdown of object the semantic definition of the proxy relates to. The Tag attribute can be used to assign a human... more

IfcQuantitySet is the the abstract supertype for all quantity sets attached to objects. The quantity set is a container class that holds the individual quantities within a quantity tree. These quantities are interpreted according to their name attribute and classified according to their measure type. Some quantity sets are included in the IFC specification and have a predefined set of quantities indicated by assigning a significant name. These quantity sets are listed as "quantity sets" within this specification. Quantity sets applicable to certain objects are listed in the object specification.
An IfcPropertySetTemplate may define the underlying structure, i.e. the required... more

A rail is a mainly linear built element that has a special section profile. Rail is distinctive from built elements with similar geometric shapes (e.g. beam, member) that its major function is to ensure guidance of moving for vehicles or other kinds of machineries.
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The railing is a frame assembly adjacent to human or vehicle circulation spaces and at some space boundaries where it is used in lieu of walls or to complement walls. Designed as an optional physical support, or to prevent injury or damage, either by falling or collision.
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A ramp is a vertical passageway which provides a human or vehicle circulation link between one floor level and another floor level at a different elevation. It can include a landing as an intermediate floor slab. A ramp normally does not include steps.
The IfcRamp can either be represented:... more

A ramp comprises a single inclined segment, or several inclined segments that are connected by a horizontal segment, referred to as a landing. A ramp flight is the single inclined segment and part of the ramp construction. In case of single flight ramps, the ramp flight and the ramp are identical.
An IfcRampFlight is an aggregated part of an IfcRamp realized through the IfcRelAggregates relationship, the ramp flight is therefore included in the set of IfcRelAggregates.RelatedObjects. An IfcRampFlight connects the floor slab of zero to two different storeys (or partial storeys or landings) within a building. The connection relationship between... more

IfcReinforcementDefinitionProperties defines the cross section properties of reinforcement included in reinforced concrete building elements.
This subtype of IfcPropertySetDefinition is used to define the reinforcement properties in early design stages, such as in requirement definition or scheme design. In later design stages explicit instances of subtypes of IfcReinforcingElement are used. The intended usage may be indicated using the DefinitionType attribute value as a designator: recommended values are 'Reinforcement area requirement' or 'Reinforcement configuration requirement'. Other values may be used according to local standards.
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A reinforcing element represents bars, wires, strands, meshes, tendons, and other components embedded in concrete in such a manner that the reinforcement and the concrete act together in resisting forces.
One or several instances of subtypes of IfcReinforcingElement should always have a defining instance of a respective subtype of IfcReinforcingElementType. The type object holds shape and material information.
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The IfcRelAdheresToElement is an objectified relationship between an element and one to many surface feature elements that adhere to the surface of the element. The relationship is defined to be a 1 to many relationship. The IfcRelAdheresToElement establishes an aggregation relationship between the main element and a sub ordinary surface feature.
The IfcRelAdheresToElement implies a surface interface between the geometric bodies of the element and the surface feature. As with all decomposition relationships it determines:... more

The aggregation relationship IfcRelAggregates is a special type of the general composition/decomposition (or whole/part) relationship IfcRelDecomposes. The aggregation relationship can be applied to all subtypes of IfcObjectDefinition. Decompositions imply a dependency, implying that the whole depends on the definition of the parts and the parts depend on the existence of the whole. The behavior that is implied from the dependency relationship has to be established inside the applications.
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The assignment relationship, IfcRelAssigns, is a generalization of "link" relationships among instances of IfcObject and its various 1st level subtypes. A link denotes the specific association through which one object (the client) applies the services of other objects (the suppliers), or through which one object can navigate to other objects.
The client is denoted as the relating object and is established at the level of the specific, instantiable subtypes of IfcRelAssigns. The suppliers are denoted as the related objects and they are established by the RelatedObjects attribute.

The objectified relationship IfcRelAssignsToActor handles the assignment of objects (subtypes of IfcObject) to an actor (subtypes of IfcActor). The IfcRelAssignsToActor objectified relationship defines a relationship between an IfcActor and one or many objects. A particular role of the actor played in that relationship can be associated. If specified, it takes priority over the role that may be directly assigned to the person or organization.

The objectified relationship IfcRelAssignsToControl handles the assignment of control objects (represented by subtypes of IfcControl) to other objects (represented by subtypes of IfcObject, with the exception of controls).... more

The objectified relationship IfcRelAssignsToGroup handles the assignment of object definitions (individual object occurrences as subtypes of IfcObject, and object types as subtypes of IfcTypeObject) to a group (subtypes of IfcGroup). The relationship handles the assignment of group members to the group object. It allows for grouping arbitrary objects within a group, including other groups. The grouping relationship can be applied in a recursive manner. The resulting group is of type IfcGroup.
The inherited attribute RelatedObjects gives the references to the objects, which are the elements within the group. The RelatingGroup is the group that comprises all elements. The same object... more

The objectified relationship IfcRelAssignsToGroupByFactor is a specialization of the general grouping mechanism. It allows to add a factor to define the ratio that applies to the assignment of object definitions (individual object occurrences as subtypes of IfcObject and object types as subtypes of IfcTypeObject) to a group (subtypes of IfcGroup). The ratio can be used to define a percentage assignment. For example, a Factor of 0.8 would indicate that the object is assigned by 80% to the group, or a Factor of 2.5 would indicate the object is assigned with a weight factor of 2.5 to the group.
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The objectified relationship IfcRelAssignsToProcess handles the assignment of one or many objects to a process or activity. An object can be a product that is the item the process operates on. Processes and activities can operate on things other than products, and can operate in ways other than input and output.... more

The objectified relationship IfcRelAssignsToProduct handles the assignment of objects (subtypes of IfcObject) to a product (subtypes of IfcProduct). The Name attribute should be used to classify the usage of the IfcRelAssignsToProduct objectified relationship. The following Name values are proposed:... more

The objectified relationship IfcRelAssignsToResource handles the assignment of objects (as subtypes of IfcObject), acting as a resource usage or consumption, to a resource (as subtypes of IfcResource).... more

The association relationship IfcRelAssociates refers to sources of information (most notably a classification, library, document, approval, constraint, or material). The information associated may reside internally or externally of the project data. There is no dependency implied by the association.
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This entity is used to apply approval information defined by IfcApproval, in IfcApprovalResource schema, to subtypes of IfcRoot.

The objectified relationship IfcRelAssociatesClassification handles the assignment of a classification item (items of the select IfcClassificationSelect) to objects occurrences (subtypes of IfcObject) or object types (subtypes of IfcTypeObject).
The relationship is used to assign a classification item, or a classification system itself to objects. Depending on the type of the RelatingClassification it is either:... more

This entity is used to apply constraint information defined by IfcConstraint, in the IfcConstraintResource schema, to subtypes of IfcRoot.

The objectified relationship (IfcRelAssociatesDocument) handles the assignment of a document information (items of the select IfcDocumentSelect) to objects occurrences (subtypes of IfcObject) or object types (subtypes of IfcTypeObject). The relationship is used to assign a document reference or a more detailed document information to objects. A single document reference can be applied to multiple objects.

The objectified relationship (IfcRelAssociatesLibrary) handles the assignment of a library item (items of the select IfcLibrarySelect) to subtypes of IfcObjectDefinition or IfcPropertyDefinition. The relationship is used to assign a library reference or a more detailed link to a library information to objects, property sets or types. A single library reference can be applied to multiple items.

IfcRelAssociatesMaterial is an objectified relationship between a material definition and elements or element types to which this material definition applies.
The material definition can be:... more

Associates objects with a profile. In particular, it can be used for indicating which SuperelevationEvent or WidthEvent has been used as basis for dimensioning a particular OpenCrossProfile.

IfcRelConnects is a connectivity relationship that connects objects under some criteria. As a general connectivity it does not imply constraints, however subtypes of the relationship define the applicable object types for the connectivity relationship and the semantics of the particular connectivity.

This objectified relationship provides the generalization of the connectivity between elements. It is a 1 to 1 relationship. The concept of two elements being physically or logically connected is described independently from the connecting elements. The connectivity may be related to the shape representation of the connected entities by providing a connection geometry.... more

The IfcRelConnectsPathElements relationship provides the connectivity information between two elements which have path information. This objectified relationship provides the additional information required to describe the connection between two path based elements that might have single or multiple layers of material. The connection type specifies where at the path-based element a connection is given (at the start, in the middle or at the end).
The connection is described by a connection geometry, given within the object coordinate systems of the RelatingElement and of the RelatedElement. In case of IfcWallStandardCase as the RelatingElement and RelatedElement the connection geometry is provided by the... more

IfcRelConnectsPortToElement is a relationship between a distribution element and dynamically connected ports where connections are realized to other distribution elements.
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An IfcRelConnectsPorts relationship defines the relationship that is made between two ports at their point of connection. It may include the connection geometry between two ports. This objectified relationship is required for defining how two instances of IfcPort connect together. Each of the ports is logically contained within the IfcDistributionElement by using the ordered collection IfcRelNests.
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The IfcRelConnectsStructuralActivity relationship connects a structural activity (either an action or reaction) to a structural member, structural connection, or element.

The entity IfcRelConnectsStructuralMember defines all needed properties describing the connection between structural members and structural connection objects (nodes or supports).
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The entity IfcRelConnectsWithEccentricity adds the definition of eccentricity to the connection between a structural member and a structural connection (representing either a node or support).

IfcRelConnectsWithRealizingElements defines a generic relationship that is made between two elements that require the realization of that relationship by means of further realizing elements. An IfcRelConnectsWithRealizingElements is a specialization of IfcRelConnectsElement where the connecting operation has the additional attribute of (one or many) realizing elements that may be used to realize or further qualify the relationship.

This objectified relationship is used to assign elements to a certain level of the spatial project structure. Any element can only be assigned once to a certain level of the spatial structure. The question, which level is relevant for which type of element, can only be answered within the context of a particular project and might vary within the various regions.
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The IfcRelCoversBldgElements relationship is an objectified relationship between an element and one to many coverings, which cover that element.
The IFC specification provides two relationships:... more

This objectified relationship relates a space object to one or many coverings, which faces (or is assigned to) the space.
The IFC specification provides two relationships:... more

The objectified relationship IfcRelDeclares handles the declaration of objects (subtypes of IfcObject) or properties (subtypes of IfcPropertyDefinition) to a project or project library (represented by IfcProject, or IfcProjectLibrary).

The decomposition relationship, IfcRelDecomposes, defines the general concept of elements being composed or decomposed. The decomposition relationship denotes a whole/part hierarchy with the ability to navigate from the whole (the composition) to the parts and vice versa. Decompositions may be constrained by requiring both, the whole and its parts, to be of the same type - thus establishing a nesting relationship. Or they may require some form of physical containment, thus establishing special types of aggregation relationships.
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This class represents a generic and abstract relationship which subtypes are used to:... more

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The objectified relationship IfcRelDefinesByProperties defines the relationships between property set definitions and objects. Properties are aggregated in property sets. Property sets can be either directly assigned to occurrence objects using this relationship, or assigned to an object type and assigned via that type to occurrence objects. The assignment of an IfcPropertySet to an IfcTypeObject is not handled via this objectified relationship, but through the direct relationship HasPropertySets at IfcTypeObject.
The IfcRelDefinesByProperties is an N-to-N relationship, as it allows for the assignment of one or more property sets to one or more objects. Those objects then share the same property definition.... more

The objectified relationship IfcRelDefinesByTemplate defines the relationships between property set template and property sets. Common information about property sets, e.g. the applicable name, description, contained properties, is defined by the property set template and assigned to all property sets.
The IfcRelDefinesByTemplate is a 1-to-N relationship, as it allows the assignment of one property set template to a single or to many property sets or quantity sets. Those property sets then share the same property set template definition.

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IfcRelFillsElement is an objectified relationship between an opening element and an element that fills (or partially fills) the opening element. It is an one-to-one relationship.

This objectified relationship between a distribution flow element occurrence and one-to-many control element occurrences indicates that the control element(s) sense or control some aspect of the flow element. It is applied to IfcDistributionFlowElement and IfcDistributionControlElement.
This relationship may be used to indicate an operational relationship such as an actuator operating a valve, damper, or switch. It may also be used to indicate a sensing relationship such as a sensor detecting conditions of fluid flow. This relationship implies a sensing or controlling relationship; if elements are merely connected without any control relationship, then IfcRelConnectsElements should be used.

The IfcRelInterferesElements objectified relationship indicates that two elements interfere. It is a 1 to 1 relationship, and the concept of two elements interfering physically or logically is described independently of the elements.
The interference may be related to the shape representation of the entities by providing an interference geometry or zone:... more

The nesting relationship IfcRelNests is a special type of the general composition/decomposition (or whole/part) relationship IfcRelDecomposes. The nesting relationship can be applied to all non physical subtypes of object and object types, namely processes, controls (like cost items), and resources. It can also be applied to physical subtypes of object and object types, namely elements having ports. The nesting implies an order among the nested parts.

An IfcRelPositions relationship defines the relationship that positions a product related to a positioning element.

The IfcRelProjectsElement is an objectified relationship between an element and one projection element that creates a modifier to the shape of the element. The relationship is defined to be a 1:1 relationship, if an element has more than one projection, several relationship objects have to be used, each pointing to a different projection element. The IfcRelProjectsElement establishes an aggregation relationship between the main element and a sub ordinary addition feature.
The IfcRelProjectsElement implies a Boolean operation of addition for the geometric bodies of the element and the feature element. As with all decomposition relationships it determines:... more

The objectified relationship, IfcRelReferencedInSpatialStructure is used to assign elements in addition to those levels of the project spatial structure, in which they are referenced, but not primarily contained. It is also used to connect a system to the relevant spatial element that it serves.... more

IfcRelSequence is a sequential relationship between processes where one process must occur before the other in time and where the timing of the relationship may be described as a type of sequence. The relating process (IfcRelSequence.RelatingProcess) is considered to be the predecessor in the relationship (has precedence) whilst the related process (IfcRelSequence.RelatedProcess) is the successor. IfcRelSequence is defined as one-to-one relationship; therefore it assigns one predecessor to one successor.
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This entity is an objectified relationship that defines the relationship between a system and the sites, buildings, storeys, spaces, or spatial zones, it serves. Examples of systems are:... more

The space boundary defines the physical or virtual delimiter of a space by the relationship IfcRelSpaceBoundary to the surrounding elements.
The IfcRelSpaceBoundary is defined as an objectified relationship that handles the element to space relationship by objectifying the relationship between an element and the space it bounds. It is given as a one-to-one relationship, but allows each element (including virtual elements and openings) to define many such relationship and each space to be defined by many such relationships.
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The 1st level space boundary defines the physical or virtual delimiter of a space by the relationship IfcRelSpaceBoundary1stLevel to the surrounding elements. 1st level space boundaries are characterized by:
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The 2nd level space boundary defines the physical or virtual delimiter of a space by the relationship IfcRelSpaceBoundary2ndLevel to the surrounding elements. 2nd level space boundaries are characterized by:
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IfcRelVoidsElement is an objectified relationship between a building element and one opening element that creates a void in the element. It is a one-to-one relationship. This relationship implies a Boolean operation of subtraction between the geometric bodies of the element and the opening.
The following image shows the insertion of a void into a wall that is represented by the relationship IfcRelVoidsElement. The opening is created within the wall by IfcWall(StandardCase) o-- IfcRelVoidsElement --o IfcOpeningElement.
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IfcRelationship is the abstract generalization of all objectified relationships in IFC. Objectified relationships are the preferred way to handle relationships among objects. This allows to keep relationship specific properties directly at the relationship and opens the possibility to later handle relationship specific behavior.
There are two different types of relationships, 1-to-1 relationships and 1-to-many relationship. used within the subtypes of IfcRelationship. The following convention applies to all subtypes:... more

A roof is the covering of the top part of a building, it protects the building against the effects of weather. The IfcRoof can either be represented:... more

IfcRoot is the most abstract and root class for all entity definitions that roots in the kernel or in subsequent layers of the IFC specification. It is therefore the common supertype of all IFC entities, beside those defined in an IFC resource schema. All entities that are subtypes of IfcRoot can be used independently, whereas resource schema entities, that are not subtypes of IfcRoot, are not supposed to be independent entities. The IfcRoot assigns the globally unique ID, and the ownership and history information to the entity. In addition it may provide for a name and a description about the... more

The IfcSecondOrderPolynomialSpiral is a specialization of IfcSpiral. The curvature κ and radius of the curvature ρ, at any point of the curve, are related to the arc length s by the second order formulae:
Interpretation of the parameters:
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A segmented reference curve is constructed from a referenced base curve (BaseCurve) that should be used for positioning of a list of IfcCurveSegment occurrences (in most cases, there can be exceptions). The type of the base curve that IfcCurveSegment references provides the information of the interpolation method between the start point of the segment and its end point defined by the segment length of the IfcCurveSegment.ParentCurve.

The IfcSeventhOrderPolynomialSpiral is a specialization of IfcSpiral. The curvature κ and radius of the curvature ρ, at any point of the curve, are related to the arc length s by the seventh order formula:

Interpretation of the parameters:
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Shading devices are purpose built devices to protect from the sunlight, from natural light, or screening them from view. Shading devices can form part of the facade or can be mounted inside the building, they can be fixed or operable.
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A sign is a notice on display that gives information or instructions in a written, symbolic or other form. Signs are passive with the most common form of a pictorial panel. An instance of IfcSign refers to the occurrence of an individual panel which can be applied to a surface such as a wall or be aggregated within a Signal Assembly which can include multiple sign occurrences and the associated supporting structural elements (see Signal Assembly for examples).
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IfcSimpleProperty is a generalization of a single property object. Various subtypes of IfcSimpleProperty establish different ways in which a property value can be set.

The IfcSimplePropertyTemplate defines the template for all dynamically extensible properties, either the subtypes of IfcSimpleProperty or the subtypes of IfcPhysicalSimpleQuantity. The individual property templates are interpreted according to their Name attribute and may have a predefined template type, property units, and property measure types. The correct interpretation of the attributes:... more

This class represents a type of spiral curve for which the curvature change is dependent on the sine function. It is also known as the Klein curve.

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A slab is a component of the construction that may enclose a space vertically. The slab can provide the lower support (floor) or upper construction (roof slab) in any space in a building. Only the core or constructional part of this construction is considered to be a slab. The upper finish (flooring, roofing) and the lower finish (ceiling, suspended ceiling) are considered to be coverings. A special type of slab is the landing, described as a floor section to which one or more stair flights or ramp flights connect.
There are two main representations for slab occurrences:... more

A spatial element is the generalization of all spatial elements that might be used to define a spatial structure or to define spatial zones.
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Spirals are curves that revolve around a point while increasing its length. In general, these curves are parameterized in the following way: ... more

A stair is a vertical passageway allowing occupants to walk (step) from one floor level to another floor level at a different elevation. It may include a landing as an intermediate floor slab. The IfcStair can either be represented:... more

A stair flight is an assembly of building components in a single "run" of stair steps (not interrupted by a landing). The stair steps and any stringers are included in the stair flight. A winder is also regarded a part of a stair flight.
An IfcStairFlight is normally aggregated by an IfcStair through the IfcRelAggregates relationship, the stair flight is then included in the set of IfcRelAggregates.RelatedObjects. An IfcStairFlight normally connects the floor slab of zero to two different storeys (or partial storeys, or landings) within a building. The connection relationship between the IfcStairFlight and the IfcSlab can be expressed... more

A structural action is a structural activity that acts upon a structural item or building element. Structural actions are grouped into either an IfcStructuralLoadGroup of predefined type LOAD_GROUP or, more often, an IfcStructuralLoadCase. This is accomplished via the inverse relationship HasAssignments and an IfcRelAssignsToGroup relationship object. IfcStructuralLoadGroup.LoadGroupFor or IfcStructuralLoadCase.LoadGroupFor respectively refers to the structural analysis model(s) in which the loads are used.
It is possible to establish relationships between actions in one analysis model and reactions in another analysis model which cause the actions. For example, a support reaction from one structural system can be taken over as a load... more

The abstract entity IfcStructuralActivity combines the definition of actions (such as forces, displacements, etc.) and reactions (support reactions, internal forces, deflections, etc.) which are specified by using the basic load definitions from the IfcStructuralLoadResource.
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The IfcStructuralAnalysisModel is used to assemble all information needed to represent a structural analysis model. It encompasses certain general properties (such as analysis type), references to all contained structural members, structural supports or connections, as well as loads and the respective load results.
Important functionalities for the description of an analysis model are derived from existing IFC entities:... more

A structural curve action defines an action which is distributed over a curve. A curve action can be connected with a curve member or curve connection, or surface member or surface connection.
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This entity defines a reaction which occurs distributed over a curve. A curve reaction can be connected with a curve member or curve connection, or surface member or surface connection.
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The abstract entity IfcStructuralItem is the generalization of structural members and structural connections, that is, analysis idealizations of elements in the building model. It defines the relation between structural members and connections with structural activities (actions and reactions).
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This entity defines an action with constant value which is distributed over a curve.
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A load case is a load group, commonly used to group loads from the same action source.
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The entity IfcStructuralLoadGroup is used to structure the physical impacts. By using the grouping features inherited from IfcGroup, instances of IfcStructuralAction (or its subclasses) and of IfcStructuralLoadGroup can be used to define load groups, load cases and load combinations. (See also IfcLoadGroupTypeEnum.)
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