IFC 4.3.x development

5.1.3.11 IfcProject

Change log

IFC4

additions where_rulesCorrectContext
additions where_rulesHasName
additions where_rulesNoDecomposition
deletions attributes LongName
deletions attributes Phase
deletions attributes RepresentationContexts
deletions attributes UnitsInContext
deletions where_rulesWR31
deletions where_rulesWR32
deletions where_rulesWR33
modificationssupertype Changed from IfcObject to IfcContext

IFC4X1

modificationswhere_rules CorrectContext definitionChanged from not(exists(self\IfcContext.RepresentationContexts)) or (sizeof(query(Temp <* self\IfcContext.RepresentationContexts | 'ifc4.ifcgeometricrepresentationsubcontext' in typeof(Temp))) = 0) to not(exists(self\IfcContext.RepresentationContexts)) or (sizeof(query(Temp <* self\IfcContext.RepresentationContexts | 'ifc4x1.ifcgeometricrepresentationsubcontext' in typeof(Temp))) = 0)

IFC4X2

modificationswhere_rules CorrectContext definitionChanged from not(exists(self\IfcContext.RepresentationContexts)) or (sizeof(query(Temp <* self\IfcContext.RepresentationContexts | 'ifc4x1.ifcgeometricrepresentationsubcontext' in typeof(Temp))) = 0) to not(exists(self\IfcContext.RepresentationContexts)) or (sizeof(query(Temp <* self\IfcContext.RepresentationContexts | 'ifc4x2.ifcgeometricrepresentationsubcontext' in typeof(Temp))) = 0)

IFC4X3_RC3

modificationswhere_rules CorrectContext definitionChanged from not(exists(self\IfcContext.RepresentationContexts)) or (sizeof(query(Temp <* self\IfcContext.RepresentationContexts | 'ifc4x2.ifcgeometricrepresentationsubcontext' in typeof(Temp))) = 0) to not(exists(self\IfcContext.RepresentationContexts)) or (sizeof(query(Temp <* self\IfcContext.RepresentationContexts | 'ifc4x3_rc3.ifcgeometricrepresentationsubcontext' in typeof(Temp))) = 0)

5.1.3.11.1 Semantic definitions at the entity

IfcProject indicates the undertaking of some design, engineering, construction, or maintenance activities leading towards a product. The project establishes the context for information to be exchanged or shared, and it may represent a construction project but does not have to. The IfcProject's main purpose in an exchange structure is to provide the root instance and the context for all other information items included.

The context provided by the IfcProject includes:

  • the default units
  • the geometric representation context for exchange structures including shape representations
    • the project coordinate system
    • the coordinate space dimension
    • the precision used within the geometric representations
    • optionally the indication of the true north
    • optionally the map conversion between the project coordinate system and the geospatial coordinate reference system.

HISTORY  New entity in IFC1.0

IFC4 CHANGE  The attributes RepresentationContexts and UnitsInContext are made optional and are promoted to supertype IfcContext.

Informal Propositions:

  1. There shall only be one project within the exchange context. This is enforced by the global rule IfcSingleProjectInstance.

Formal Propositions

HasName

The Name attribute has to be provided for IfcProject. It is the short name for the project.

CorrectContext

If a RepresentationContexts relation is provided then there shall be no instance of IfcGeometricRepresentationSubContext directly included in the set of RepresentationContexts.

NoDecomposition

The IfcProject represents the root of the any decomposition tree. It shall therefore not be used to decompose any other object definition.

# 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.
IfcContext
5 ObjectType OPTIONAL IfcLabel The object type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes.

> NOTE  Subtypes of IfcContext do not introduce a PredefinedType attribute, therefore the usage of ObjectType is not bound to the selection of USERDEFINED within the PredefinedType enumaration.
6 LongName OPTIONAL IfcLabel Long name for the context as used for reference purposes.
7 Phase OPTIONAL IfcLabel Current project phase, or life-cycle phase of this project. Applicable values have to be agreed upon by view definitions or implementer agreements.
8 RepresentationContextsOPTIONAL SET [1:?] OF IfcRepresentationContext Context of the representations used within the context. When the context is a project and it includes shape representations for its components, one or several geometric representation contexts need to be included that define e.g. the world coordinate system, the coordinate space dimensions, and/or the precision factor.

> IFC4 CHANGE  The attribute has been changed to be optional. Change made with upward compatibility for file based exchange.
9 UnitsInContext OPTIONAL IfcUnitAssignment Units globally assigned to measure types used within the context.

> IFC4 CHANGE  The attribute has been changed to be optional. Change made with upward compatibility for file based exchange.
IsDefinedBy SET [0:?] OF IfcRelDefinesByProperties FOR RelatedObjectsSet of relationships to property set definitions attached to this context. Those statically or dynamically defined properties contain alphanumeric information content that further defines the context.

> IFC4 CHANGE  The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange.
Declares SET [0:?] OF IfcRelDeclares FOR RelatingContext Reference to the IfcRelDeclares relationship that assigns the uppermost entities of includes hierarchies to this context instance.

> NOTE  The spatial hiearchy is assigned to IfcProject using the IfcRelAggregates relationship. This is a single exception due to compatibility reasons with earlier releases.

5.1.3.11.1 Entity inheritance

dot_inheritance IfcProject IfcProject IfcContext IfcContext IfcProject->IfcContext IfcProjectLibrary IfcProjectLibrary IfcProjectLibrary->IfcContext IfcObjectDefinition IfcObjectDefinition IfcContext->IfcObjectDefinition IfcObject IfcObject IfcObject->IfcObjectDefinition IfcRoot IfcRoot IfcObjectDefinition->IfcRoot IfcTypeObject IfcTypeObject IfcTypeObject->IfcObjectDefinition IfcPropertyDefinition IfcPropertyDefinition IfcPropertyDefinition->IfcRoot IfcRelationship IfcRelationship IfcRelationship->IfcRoot

5.1.3.11.2 Definitions applying to General Usage

5.1.3.11.2.1 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.

5.1.3.11.2.2 Identity

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

5.1.3.11.2.3 Project Classification Information

5.1.3.11.2.4 Project Declaration

The IfcProject is also the context for other information about the construction project such as a work plan. Non-product structures are assigned by their first level object to IfcProject using the IfcRelDeclares relationship. The IfcProject provides the context for work plans (or other non-product based) descriptions of the construction project. It is handled by the objectified relationship IfcRelDeclares.

NOTE  The spatial structure and the schedule structure can be decomposed. For example the IfcBuilding can be decomposed into IfcBuildingStorey's, and the IfcWorkPlan can be decomposed into IfcWorkSchedule's.
NOTE  The products and tasks can be decomposed further. For example the IfcCurtainWall can be decomposed into IfcMember and IfcPlate, the IfcTask can be decomposed into other IfcTask's.
NOTE  The products and tasks can have direct linking relationships. For example the IfcCurtainWall can be assigned to a IfcTask as an input or output for a construction schedule.

Figure 128 illustrates the use of IfcProject as context for work plans or work schedules.

project relationships

Figure 128 — Project spatial and work plan structure

Type
'IfcProjectLibrary'
'IfcPropertySetTemplate'
'IfcTypeObject'
'IfcActor'
'IfcControl'
'IfcGroup'
'IfcProcess'
'IfcResource'

5.1.3.11.2.5 Project Document Information

5.1.3.11.2.6 Project Global Positioning

The representation context of the project refers to a global positioning, i.e. the local engineering coordinate system of the project has a mapping to a defined projected coordinate system (a rectangular map coordinate system, as used in GIS systems)

5.1.3.11.2.7 Project Library Information

5.1.3.11.2.8 Project Representation Context

ContextType ContextIdentifier
'3D' 'Model'
'2D' 'Plan'

5.1.3.11.2.9 Project Units

5.1.3.11.2.10 Revision Control

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

5.1.3.11.2.11 Spatial Decomposition

The IfcProject is used to reference the root of the spatial structure of a building or other construction project (that serves as the primary project breakdown and is required to be hierarchical). The spatial structure elements are linked together, and to the IfcProject, by using the objectified relationship IfcRelAggregates.

The following constraints are applied to using the relationshio IfcRelAggregates in context of IfcProject

NOTE  The anomaly to use the composition structure through IfcRelAggregates for assigning the uppermost spatial container to IfcProject is due to upward compatibility reasons with earlier releases of this standard.

Figure 129 illustrates project relationships with spatial structures, elements, and element type libraries.

spatial decomposition relationships

Figure 129 — Project spatial structure, products and product type library

5.1.3.11.3 Formal representations

ENTITY IfcProject
 SUBTYPE OF (IfcContext);
 WHERE
	HasName : EXISTS(SELF\IfcRoot.Name);
	CorrectContext : NOT(EXISTS(SELF\IfcContext.RepresentationContexts)) OR
(SIZEOF(QUERY(Temp <* SELF\IfcContext.RepresentationContexts |
 'IFC4X3_DEV_a1492713.IFCGEOMETRICREPRESENTATIONSUBCONTEXT' IN TYPEOF(Temp)
  )) = 0);
	NoDecomposition : SIZEOF(SELF\IfcObjectDefinition.Decomposes) = 0;
END_ENTITY;