Functional parts

Functional parts refer to logical grouping of rules that involve similar types of validation.

These functional part prefixes are used in the naming of the normative rules and are reported in the results listed by the validation service.

Catalog

Below is the list of the IFC functional parts.

TAG	FUNCTIONAL PART	DESCRIPTION
PJS	Project definition	The ability to define the overall context and directory of objects within the model. Among others, the context definition includes default units and geometric representation context for shape representations.
GRF	Georeferencing	The ability to accurately define the geographic location and orientation of the model relative to a reference coordinate system, such as a national or global coordinate system.
BLT	Built elements (kickable)	The ability to model various building and infrastructure elements, including walls, floors, roofs, stairs, doors, windows, columns, road pavements, bridge decks, railway track elements, etc.
ASM	Assemblies (kickable)	The ability to model elements composed of / constructed by other elements. For example, a roof might be assembled from a series of prefabricated truss components.
SPA	Spaces (non-kickable)	The ability to model spaces, such as rooms, hallways, clearance zones, and circulation areas.
VRT	Virtual elements (non-kickable)	The ability to model spatial element used to provide imaginary, placeholder, or provisional areas (e.g. clearance), volumes, and boundaries. Virtual elements are not displayed, do not have quantities, materials, or other measures.
GEM	*Geometry representation	The ability to represent built elements and spaces using various geometry types, including parametric, mesh, and voxel-based representations.
OJP	*Object placement	The ability to define the location, orientation, and scale of built elements and systems within the building model.
POS	*Positioning elements	The ability to define (virtual) objects that are used to position other elements relatively. Includes grids, alignments, and referents.
OJT	Objects typing	The ability to define elements (and unfortunately not systems) based on their type or function within the model, allowing reusability of information by the occurrence of such types.
GRP	Groups (non-kickable)	The ability to group objects related by functional or logical criteria. Used, for example to model building systems, such as HVAC (heating, ventilation, and air conditioning) systems; to group assets that have the same maintenance schedule; to group all terminals of a fire-protection system.
SPS	Spatial breakdown	The ability to define spatial organisation within a building or infrastructure project. This includes the hierarchical relationships between spatial containers, such as buildings within a site, storeys within a building and rooms within a storey.
MAT	Materials	The ability to define materials assigned to elements.
PSE	Properties for object	The ability to define properties of elements and systems, such as their performance characteristics.
QTY	Quantities for objects	The ability to define quantities of elements, such as their dimensions, volume, area, weight.
CLS	Classification reference	The ability to classify elements, materials, and systems according to various classification systems, such as the UNIFORMAT or Omniclass classification systems.
ANN	Annotations	The ability to add annotations to elements and spaces, such as labels, notes, and dimensions.
LAY	Presentation layer	The ability to assign layers (also known as, CAD layer) to collection of elements. This is used mainly for grouping and visibility control, and in general to organise geometry into groups that may be shown or hidden.
CTX	Presentation Colours and Textures	The ability to assign colour, texture and other presentation appearance information to objects.
POR	Port connectivity & nesting	The ability to define ports (as means for an element to connect to other elements) and the relationship that is made between two ports.
STR	Structural items and actions	The ability to define structural members and structural connections, as analysis idealizations of built elements. And the ability to define actions (such as forces, displacements, etc.) and reactions (support reactions, internal forces, deflections, etc.) associated to structural items and specified by using the basic load definitions.
CST	Costing	The ability to assign costing information to objects.
SDL	Scheduling of activities	The ability to assign scheduling information to objects.
LIB	Library reference	The ability to associate library entities, such as from a product library or external database to objects and object types.
DOC	Documentation reference	The ability to associate reference to documentation to objects.
CTR	Constraints	The ability to model constraints on building elements, such as minimum and maximum dimensions or clearances, and to enforce these constraints during design and construction.
VER	Versioning / revision control	The ability to track changes to building data over time and to maintain a history of changes.

*These 3 functional parts are further decomposed as indicated below.

Geometry representation sub-parts

TAG	FUNCTIONAL PART	DESCRIPTION
AXG	Axis geometry	This involves representing the geometry using a set of axes, where each axis consists of a position in 3D space and a direction vector. This can be useful for representing geometry that follows a certain pattern or direction, such as walls, beams, columns, or other elements. In IFC, axis geometry can be represented using the IfcCartesianPoint and IfcDirection classes, which define the position and direction of the axes, respectively.
ALS	Alignment geometry	This involves representing the geometry using a collection of segments that define a linear path in 3D space. This can be useful for representing linear objects such as roads, railways, or pipelines.
PBG	Point-based geometry	This involves representing geometry using a collection of individual points in 3D space. Point-based geometry can be useful for representing large-scale environments or for creating simplified representations of more complex geometry. Point-based geometry can be represented in IFC using a range of different point types, such as 3D point clouds or scattered point data.
TAS	Tessellated (i.e. meshes)	This involves representing geometry using a collection of interconnected vertices, edges, and faces, which are used to approximate a smooth surface. Tessellated geometry can be useful for representing organic or irregular shapes, or for creating low-resolution representations of more complex geometry. In IFC, tessellated geometry can be represented using a range of different mesh types, such as triangular, quadrilateral, or polyhedral meshes.
BRP	Boundary Representation (BREP)	This involves representing geometry using a collection of connected surfaces and edges. BREP geometry can be used to represent complex shapes with curved surfaces or unusual topology. BREP geometry can be represented in IFC using IfcFacetedBrep for polygonal meshes or IfcManifoldSolidBrep for more complex solid geometry. These entities can be further described using a collection of geometric representations such as IfcCartesianPoint, IfcPolyLoop, and IfcSurface.
CSG	Constructive Solid Geometry (CSG)	This involves creating complex geometry by combining simpler shapes using Boolean operations such as union, intersection, and difference. CSG can be useful for creating complex shapes with predictable and repeatable geometry. CSG can be represented in IFC using the IfcBooleanResult entity, which defines the Boolean operation to be applied to a set of one or more shape representations.
SWE	Sweeps (i.e., extrusions, lofts, blends)	This involves taking a 2D shape (often called the “profile”) and moving it along a 3D path, generating a 3D shape. The resulting shape is typically smooth and continuous, with its cross-section changing gradually along the length of the path. Sweep geometry can be useful for representing a variety of objects, such as pipes, cables, and architectural details like moldings. In IFC, sweep geometry can be represented using the IfcExtrudedAreaSolid, IfcRevolvedAreaSolid, and IfcSweptAreaSolid entities.
TFM	Transformations	Transformation geometry involves representing geometry using spatial transformations, such as rotations, translations, and scaling. It allows for the modification of existing geometry without the need to create new geometry from scratch. Transformation geometry can be used to represent various types of transformations, including cartesian transformations, placement transformations, and composite transformations, among others. These transformations can be applied to a range of geometric entities, including points, curves, surfaces, and solids, to create new or modified geometry. In IFC, transformation geometry is represented using the IfcCartesianTransformationOperator and IfcObjectPlacement entities.
BBX	Bounding box	This involves defining an orthogonal box, oriented parallel to the axes of the object coordinate system in which it is defined and containing a geometry object, which defines the spatial extent of the latter.
MPD	Mapped geometry	This involves identifying a representation and a representation item in that representation for the purpose of mapping. The representation item defines the origin of the mapping. The representation map is used as the source of a mapping by a mapped item.
RCO	Relational constructs	Such as connection geometry, space boundaries, interference geometries. This is not a geometry category per se, but it’s a specific way geometry is used in IFC
CPD	Clipped representations	This involves visualizations of a 3D model where part of the model is “clipped” or cut away to allow for better examination of the internal structures or components. This is often done using clipping planes or sections.

Object placement sub-parts

TAG	FUNCTIONAL PART	DESCRIPTION
LOP	Local placement	The ability to define the placement of a product in relation to the placement of another product; or its absolute placement within the geometric representation context of the project.
LIP	Linear placement	The ability to define the placement of a product in relation to a curve.
GDP	Grid placement	The ability to define the placement of a product in relation to a design grid.

Positioning elements sub-parts

TAG	FUNCTIONAL PART	DESCRIPTION
GRD	Grid	The ability to define a design grid to be used as reference for object placement.
ALA, ALB	Alignment	The ability to define an alignment curve, and its components. These can be used as reference for object placement.
RFT	Referent	The ability to define a referent to be used as reference for object placement.