IFC 4.3.x development

3 Terms, definitions, and abbreviated terms

For the purpose of this document, the following definitions apply.

3.1 Terms and definitions

3.1.1 actor

person, an organization, or person acting on behalf of an organization NOTE A specialization of the general term object.

3.1.2 attribute

unit of information within an entity, defined by a particular type or reference to a particular entity NOTE There are three kinds of attributes: direct attributes, inverse attributes and derived attributes.

3.1.2.1 direct attribute

scalar values or collections including Set (unordered, unique), List (ordered), or Array (ordered, sparse) as defined in [ISO 10303-11] NOTE Similar to the term "field" in common programming languages.

3.1.2.2 inverse attribute

unit of information defining queries for obtaining related data and enforcing referential integrity NOTE Similar to the term "navigation property" in entity-relational programming frameworks.

3.1.2.3 derived attribute

unit of information computed from other attributes using an expression defined in the schema

3.1.2.4 constraints on attributes

data type restricting the values of attributes NOTE The most general constraint is about the existence of attribute values. There are basically two types: mandatory and optional attributes. Values of mandatory attributes must be provided whereas values of optional attributes may be omitted. NOTE For aggregation data types such as Set, List, or Array, the existence constraint is often refined by a minimal and maximal number of elements, which is also known as cardinality.

3.1.3 classification

categorization, the act of distributing things into classes or categories of the same type

3.1.4 constraint

restriction for a specified reason NOTE A specialization of the general term control.

3.1.5 control

directive to meet specified requirements such as for scope, time, or cost NOTE A specialization of the general term object.

3.1.6 dictionary

collection of words, terms or concepts, with their definition

3.1.7 element

tangible physical product that can be described by its shape representation, material representations, and other properties NOTE A specialization of the general term product.

3.1.7.1 element occurrence

element's position within the project coordinate system and its containment within the spatial structure

3.1.8 entity

class of information defined by common attributes and constraints as defined in ISO 10303-11 NOTE Similar to the term "class" in common programming languages but describing data structure only (not behavior such as methods).

3.1.9 external reference

link to information outside the data set, with direct relevance to the specific information the link originates from inside the data set

3.1.10 feature

parametric information and additional property information modifiying the shape representation of an element to which it applies

3.1.11 group

collection of information that fulfills a specified purpose NOTE A specialization of the general term object.

3.1.12 identification

capability to find, retrieve, report, change, or delete specific instances without ambiguity

3.1.13 instance

occurrence of an entity NOTE Similar to the term "instance of a class" in object oriented programming.

3.1.14 library

catalogue, database or holder of data, that is relevant to information in the data set NOTE It is information referenced from an external source that is not copied into the data set.

3.1.15 model

a data set, governed by the structure of an underlying schema, to meet certain data requirements NOTE Information models and building information models are examples for a model. NOTE In scope of this standard IFC models are populations of the IFC schema.

3.1.16 model view

subset of a schema, representing the data structure required to fullfil the data requirements within one or several exchange scenarios NOTE Beside being a subset of a schema, a model view (or model view definition) may also impose additional constraints to the population of the subset schema

3.1.16.1 concept

rules on using a subset of the schema structure identified as a concept template to enable a certain functionality within the context of a concept root contained in a model view NOTE The utilization of material definitions for a paticular concept root representing a wall is an example of a concept.

3.1.16.2 concept template

the specification of a subset of the schema structure to enable a certain unit of functionality NOTE The identification of the entities, attributes and constraints needed to express a material definition independently on how it is utilized later in the context of a wall is an example of a concept template.

3.1.16.3 concept root

an entity of a schema used to assign concepts to describe the required functionality NOTE A root concept often describes a model element, such as wall, air outlet, construction task, or similar, that is the root of a graph of connected entities and attributes defining the specific information items required, such as geometry, material, breakdown structure, etc.

3.1.17 object

anything perceivable or conceivable that has a distinct existence, albeit not material

3.1.17.1 object occurrence

characteristics of an object as an individual NOTE Similar to "object", "instance", "individual" in other publications.

3.1.17.2 object type

common characteristics shared by multiple object-occurrences NOTE Similar to "class", "template", "type" in other publications.

3.1.18 process

object-occurrence located in time, indicating "when"

3.1.19 product

physical or conceptual object that occurs in space NOTE It is specialization of the general term object.

3.1.20 project

encapsulation of related information for a particular purpose providing context for information contained within NOTE Context information may include default measurement units or representation context and precision.

3.1.21 property

unit of information that is dynamically defined as a particular entity instance NOTE Similar to "late-bound" or "run-time" in programming terminology.

3.1.21.1 property occurrence

unit of information providing a value for a property identified by name

3.1.21.2 property template

metadata for a property including name, description, and data type NOTE Similar in concept to "extension property" in common programming languages.

3.1.21.3 property set occurrence

unit of information containing a set of property occurrences, each having a unique name within the property set

3.1.21.4 property set template

set of property templates serving a common purpose and having applicability to objects of a particular entity NOTE Similar in concept to "extension class" in common programming languages.

3.1.22 proxy

object that does not hold a specific object type information NOTE a specialization of object occurrence.

3.1.23 quantity

measurement of a scope-based metric, specifically length, area, volume, weight, count, or time

3.1.24 relationship

unit of information describing an interaction between items

3.1.25 representation

unit of information describing how an object is displayed, such as physical shape or topology

3.1.26 resource

entity with limited availability such as materials, labor, or equipment NOTE a specialization of the general term object. NOTE the "resource definition data schemas" section is unrelated to this concept.

3.1.27 schema

the definition of the structure to organize data for storage, exchange and sharing, using a formal language NOTE The formal languages EXPRESS ISO 10303-11 and XML Schema W3C Recommendation are currently used to define the schemata of this standard

3.1.28 space

area or volume bounded actually or theoretically NOTE a specialization of the general term product.

3.1.29 type

basic information construct derived from a primitive, an enumeration, or a select of entities NOTE Similar to the "Type" construct as defined in ISO 10303-11. NOTE Similar in concept to "typedef" or "value type" in common programming languages.

3.1.29.1 select

construct that allows an attribute value to be one of multiple types or entities NOTE Similar to the "Select" construct as defined in ISO 10303-11. NOTE Similar to a "marker interface" in common programming languages.

3.1.29.2 enumeration

construct that allows an attribute value to be one of multiple predefined values identified by name NOTE Similar to the "Enumeration" construct as defined in ISO 10303-11. NOTE Similar in concept to "enum" in common programming languages.

3.2 Abbreviated terms

  • AEC: Architecture, Engineering, and Construction
  • AEC-FM: Architecture, Engineering, Construction, and Facilities Management
  • BIM: Building Information Modeling
  • GUID: Globally Unique Identifier
  • IFC: Industry Foundation Classes
  • IFD: International Framework for Dictionaries
  • MVD: Model View Definition
  • SPF or SPFF: STEP Physical File
  • STEP: STandard for the Exchange of Product data
  • URI: Uniform Resource Identifier
  • UUID: Universally Unique Identifier
  • XML: Extensible Markup Language