Glossary of Terms

4D

4D

4D = 3D + time, i.e. the linking of time aspect to the building element and space objects of the 3D-model. The time aspect may describe e.g. the installation date and time of building elements. Then 4D-simulation can be used to visualize the progress of construction in time.

5D

5D

5D = 3D + time + cost i.e. the linking of both time and cost aspects to the building element and space objects of the 3D-model. The 5D aspect may be used to describe the occurrence of cost parameters at particular times during the development of a project and may be used to visualize the expenditure, income return, life cycle cost or other developing cost pattern for a project.

 A

Abstract Entity Type

An entity type that cannot be instantiated; only non-abstract subtypes of an abstract entity type may be instantiated.

Activity

A piece of work to accomplish a result. Describes a generalized piece of doing that is not scheduled in time. This is distinct from a task that typically has a time context.

Activity Model

A model that describes an application in terms of the sequence of its activities and information flows.

Actor

A person, an organization or an organizational unit (such as a department, team etc.) involved in a project during its life cycle.

AEC

Architecture, Engineering and Construction

A phrase that may be used as an alternative to describe the building construction industry. Prevalent in US and related practice.

AEC / FM

Architecture, Engineering and Construction / Facilities Management.

A phrase that may be used as an alternative to describe the building construction industry and subsequent building operations. Prevalent in US and related practice.

AECO

Architecture, Engineering, Construction and Operation

An alternative usage to AEC/FM. More recent definition.

Aggregate

A collection of elements. In the EXPRESS language the types of aggregates are array, bag, list and set.

Aggregation

A special form of association, between a whole and its parts, in which the whole is composed of the parts.

In IFC, aggregation is a subtype of composition in which the composite element may be composed of elements of different entity types.

Application

An information system specific to the satisfaction of a set of user requirements.

API

Application Programming Interface

An interface definition that permits invoking services from application programs without knowing details of their internal implementation.

AIC

Application InterpretedConstruct

Specifies the interpretation of the STEP integrated resources to satisfy requirements for a tightly defined functional area.

AIM

Application Interpreted Model

The process, mechanism, or manner by which meaning is assigned to an abstract representation of an event, object, or concept. Within an Application Interpreted Model or AIM, the abstract representation is specified by an EXPRESS construct. Interpretation results in the creation of a new construct in an AIM that may restrict, narrow, or constrain the semantic scope of an original construct, thereby specializing it.

AM

Application Module

Common building blocks used to create modular Application Protocols (AP) within STEP. Higher-level modules are built up from lower-level modules.

AP

Application Protocol

A mechanism of the STEP standard for defining well-defined subsets of the total resource classes in STEP to be used in conceptual models supporting the data transfer needs of particular application areas.

ARM

Application Reference Model

A conceptual model in STEP that describes the information requirements and constraints of a specific application context.

Architecture

Description of the basic arrangement and connectivity of parts of a system.

Array

A type of EXPRESS aggregate that is fixed by size and the elements of which are indexed by order.

ASCII

American Standard Code for Information Interchange

A standard code for representing English characters as numbers, with each letter assigned a number from 0 to 127.

As-Is Process

A process as it is currently.

Attribute

In general, attributes represent the characteristics of objects.

E.g. Attributes defined by a building element class may be Name, Length, Weight, Price, etc. The attribute values of a specific building element of a specific building may be Name = 'Wall-123', Length=6500.0, Weight=7300, etc.

In EXPRESS, an attribute of an entity type has a name and data type, and they represent characteristics of an entity type and relationships between entity types.

Attribute Value

Attributes defined by an entity type get their specific values in the instances of the entity type.

 B

Backward Compatibility

See Downward Compatibility

Bag

A type of EXPRESS aggregate that can vary in size, the elements are not indexed by order and the elements are not required to be unique.

BIM

Building Information Model.

A shared digital representation of physical and functional characteristics of a facility founded on open standards for interoperability.  

A shared knowledge resource for information about a facility forming a reliable basis for decisions during its life-cycle from inception onward.

A basic premise is collaboration by different stakeholders at different phases of the life cycle of a facility to insert, extract, update or modify information in the process to support and reflect the roles of that stakeholder.

Boundary Representation

A modeling strategy where objects are modeled using their boundary description.

Bounding Box

A minimum bounding volume in the form of a rectangular box such that it completely contains an object.

Building Product Model

The totality of building information and digital product data, throughout the life cycle of a building.

Note: Recently, also the term Building Information Model (BIM) has been used as a synonym for building product model.

Business Object

An identifiable business concept such as customer or order.

BPEL

Business Process Execution Language

An XML-based language designed to enable task-sharing for a distributed computing or grid computing environment.

BPMN

Business Process Modeling Notation

A notation for use in the development of business process diagrams that is readily understandable by all business users, from the business analysts that create the initial drafts of the processes, to the technical developers responsible for implementing the technology that will perform those processes, and finally, to the business people who will manage and monitor those processes.

Enables XML languages designed for the execution of business processes, such as BPEL (Business Process Execution Language), to be visualized with a business-oriented notation.

BPR

Business Process Re-engineering)

An organizational process that helps to identify fundamental business objectives, formulate a detailed strategy to achieve those objectives, determine measures for success, redesign business processes, and implement new policies and procedures.

Business Rule

A statement that defines or constrains some aspect of the business.

A rule under which an organization operates.

A policy or decision that influences the process step.

 C

CAD-Layer

A mechanism within CAD-applications for grouping data. In a CAD-model a graphical entity is assigned to a layer to which may be applied operations, like visibility, filtering etc.

Cardinality

Definition of how many instances can participate into a relationship in both sides of it.

Describes the number of participants in a reference between objects/classes in a data model. For instance the link between a father and his sons is a zero-to-many reference as one father may have 0 or more sons. The link from a son to his father is a one-to-one link as a son may have one and only one (biological) father.

Cartesian Coordinates

A planar coordinate system that enables a point in 2D space to be represented by two measurements, and a point in 3D space by three measurements, relative to some defined origin and system of orthogonal axes.

Certification

In the context of IFC, a procedure by which software that implements IFC is tested and certified for conformance with IFC specification and for capability of high quality IFC data exchange.

Certification of software is done against an IFC View definition.

Certification Workshop

An open workshop which is part of the IFC software certification procedures.

In the workshop, the certification candidates have to demonstrate the capability of their software for high quality IFC data exchange. The certification workshop is preceded by testing of software using test cases, and with exchanges between the candidate software.

Change Log

In the context of IFC, documentation of the changes made to the IFC Object Model. The change log is maintained by the IAI Model Support Group.

Chapter

A geographical or language based organizational unit within the IAI organization. Chapters are the next organizational level below IAI International.

The current IAI Chapters are: Australasia, Benelux, China, French speaking, German speaking, Iberia, Italy, Japan, Korea, Nordic, North American, Singapore and UK Chapters.

CIS/2

CIMSteel Integration Standards

The product model and electronic data exchange file format for structural steel project information intended to create a seamless and integrated flow of information among all parties of the steel supply chain involved in the construction of steel framed structures.

A mapping specification between CIS/2 and IFC is defined.

CityGML

An information model for the representation of 3D urban objects. It defines the classes and relations for the most relevant topographic objects in cities and regional models with respect to their geometrical, topological, semantic and appearance properties. Included are generalization hierarchies between thematic classes, aggregations, relations between objects, and spatial properties.

It is implemented as an application schema for the Geographic Markup Language (GML).

Class

A Class describes the characteristics of similar objects.

Class Hierarchy

The Inheritance hierarchy (Is-a relationships) between the classes.

Class Library

A collection of classes, or a set of pre-built and pre-tested software components that can be used as building blocks to develop applications. Class libraries are often provided by development tool vendors and may also be purchased from third-party vendors.

Classification

A grouping of things according to common characteristics or some other principle.

Code Checking View

A view of the IFC Object Model that is designed to support the exchange of information to check for conformance with local building codes/regulations.

Compatibility

In general, capability of systems' interfaces to work with each other.

Note: With regard to data exchange files, there may be upward compatibility and downward compatibility.

Complex Instance

An instance that is an instantiation of a number of entity types at the same time. A complex instance collects together component instances from multiple classes into a single instance.

Note: Complex instance is not the same as a composition.

Note: Especially EXPRESS related concept.

Composition

In general, a relationship between a composite object and its parts.

In IFC, a type of composition where the composite element can be a composition of elements of varying types. The generic composition relationship in IFC is further subtyped into aggregation and nesting.

Note: Some times also called whole-part relationship.

CFD

Computational Fluid Dynamics

The science of determining a numerical solution to the governing equations of fluid flow whilst advancing the solution through space or time to obtain a numerical description of the complete flow field of interest

CAD

Computer Aided Design

A class of software application that performs a design function.

CADD

Computer Aided Design and Draughting

A computer aided design software application with additional features such as annotation etc. that enable the production of drawings as output.

CAFM

Computer Aided Facilities Management

A class of software application that assists with the planning, execution and recording of facilities management operations.

CAMM

Computer Aided Maintenance Management

A class of software application that assists with the planning, execution and recording of engineering maintenance management operations.

CASE

Computer Aided System Engineering

Computer Aided System Engineering. (CASE) tools are more or less complete sets of software to aid the process of making software. They typically support the creation of graphical schemas, keep track of dictionaries (repositories) of all entity classes, their attributes and relations and at last generate code in a chosen language.

Computer Interpretable Data

Representation of data in a form that can be directly interpreted by computer applications without human intervention.

Concept

Human perception of objects of reality.

Conceptual Model

A formal definition of a bounded set of facts, concepts or instructions and relationships to meet a specified requirement.

Synonym of information model

Conformance

In the context of standards, means that the implementation of the standard (e.g. applications’ data exchange interface) is done according to the definitions of the standard.

Consistency

A characteristic of a data set that the values that are dependent or derived from each other don’t have values violating these dependency rules.

Constraint

In EXPRESS or data modeling, defines restrictions to the allowable value space of instances and their attribute values.

A limiting value or boundary condition that may be applied to the value of a property of an object.

Constructed Data Types

Constructed data types of EXPRESS are enumeration and select data types.

Construction Type

Defines the decomposition structure of a building element and properties of the building element parts. Type information defines some properties of building elements that may be shared by multiple building elements.

E.g. The construction type of a wall defines the material layers of its cross section.

CSG

Constructive Solid Geometry

A geometric modeling methodology where an object is built using the boolean operators: union, subtraction and difference.

Converter

A computer application that converts data from one form to another.

Coordination View

A basic view of the IFC Object Model designed to exchange primarily shape data about the building, spaces and building elements

 D

Data

Representation of information in a formal manner suitable for communication, interpretation, or processing by human beings or computer applications.

Recorded, ordered symbols that carry information.

Database

A group of related data sets comprising data that is independent of applications, involves complex data relationships, and is protected by data security

Data Access Interface

A programming interface that allows for access to data such that the using application is separated from how the data actually is stored and managed.

DDL

Data Definition Language

A formal method for the definition of concepts and their data structures.

Data Exchange

The exchange of data between computer applications; typically using a data exchange file.

Data Exchange File

A file of data in data exchange format that is exported by the sending application for the purpose of transferring and importing the file into the receiving application.

Data Exchange Format

A computer interpretable format used for storing, accessing, transferring, and archiving data.

Data Model

An abstraction of the real world which incorporates only those properties thought to be relevant to the application at hand. The data model would normally define specific groups of entities, and their attributes and the relationships between these entities.

Usually used as a synonym for the terms conceptual or information model.

Note: Sometimes a distinction is made between the implementation technology independent conceptual model, and the data model which is planned for a specific implementation technology (e.g. the data structures of a database).

Note: An Information model for Product data is called a Product data model.

Data Quality

Indications of the degree to which data satisfies stated or implied needs.

This may include information about lineage, completeness, currency, logical consistency and accuracy of the data

Data Sharing

Common access to data in a database by a number of applications that create, use and update the data.

Data Type

The definition of the domain of values of an attribute.

Database

An organized and managed set of data that one or more applications can use and update.

Datum

A point that defines an origin and orientation of a coordinate system.

Decomposition

In general, a relationship between parts of a composite object and the composite object that is the inverse to composition

De-Facto Standard

A method or similar which has achieved a position of being the "standard" practice, without being standardized by an official standardization body.

Defined Type

In EXPRESS, defined type is a named type that can be by underlying data type be a simple type, other defined types or a Constructed data type.

Definition

A concise explanation of meaning of an item of interest.

Derived Attribute

An attribute the value of which can be derived from the values of other attributes of the object. The derivation rule can also be seen as a consistency rule between the attribute values.

DTM

Digital Terrain Model

A method of transforming elevation data into a contoured surface of a three-dimensional display.

Document

A collection of document data that is managed as a single unit.

Document Data

Document data gives a textual or graphical description (presentation) of the thing, such that humans can interpret information about the thing.

For example, a person who understands the notations of construction drawings can interpret the design for the building. However, even if the drawing would be e.g. in digital DXF-format, a computer application could automatically interpret the meaning of the graphics (lines, circles, text, ...) of the drawing.

DTD

Document Type Definition.

A definition of information content using the XML language.

Document Based

A paradigm in which information is represented using documents (presentations), text documents, schedules, drawings, etc., from the content of which the computer applications cannot interpret actual product data. Interpretation is done by humans using the documents.

Domain

The body of knowledge defining the range and scope of an area of interest in terms of elements, rules and behaviors.

Downward Compatibility

With regard to data exchange, a type of compatibility in which the data files based on a later specification release are compatible with data files based on an earlier release.

With regard to an application, an application is downward compatible is it can read, write and handle data created by an earlier release of the application.

 E

e-Commerce

The process of conducting business (buying and selling of goods and services) on the Internet, especially the World Wide Web. In practice, this term and a new term, "e-business," are often used interchangeably.

e-Government

The process of conducting government business on the Internet.

Enterprise

One or more organizations sharing a definitive mission, goals, and objectives to offer an output such as a product or service. This includes related concepts such as extended enterprise or virtual enterprise.

A large organization whose many offices, agencies, workers and partners must be able to communicate and share information effectively and efficiently.

ERP

Enterprise Resource Planning

The broad set of activities supported by multi-module application software that help a manufacturer or other business manage the important parts of its business, including product planning, parts purchasing, maintaining inventories, interacting with suppliers, providing customer service, and tracking orders. ERP can also include application modules for the finance and human resources aspects of a business. Typically, an ERP system uses or is integrated with a relational database system. The deployment of an ERP system can involve considerable business process analysis, employee retraining, and new work procedures.

Entity type

Defines the attributes and constraints for objects (i.e. the instances of the entity type) with similar characteristics.

Note: Synonym for more generic term Class. In the definitions the term entity type is used in most cases.

Enumeration Type

A data type that defines a list of possible named enumeration values.

I.e. an attribute of an enumeration type can have a value of one of the predefined enumeration values.

Event

The cause of a state change of an object.

Exchange Format

A structure and syntax for encoding data for the purpose of its exchange.

ER

Exchange Requirement

The set of information that needs to be exchanged to support a particular business requirement at a particular project stage (or stages).

The purpose of an exchange requirement is to describe the information that must be passed from one business process to enable another business process to happen.

Explicit Attribute

An attribute of an entity type that is not a derived or inverse attribute.

EXPRESS

A data definition language defined by ISO 10303-11 EXPRESS language reference manual. EXPRESS is a formal language that can be used to define product data models.

Note: IFC Object Model is defined using the EXPRESS language.

EXPRESS Model

An information model described using the EXPRESS language. An EXPRESS model may comprise a number of interrelated schemas.

EXPRESS-G

A graphical notation for the EXPRESS language. EXPRESS-G defines graphical symbols for a subset of the elements of the EXPRESS language.

EXPRESS-X

A mapping specification language for defining a mapping between data sets based on different EXPRESS-models.

EXPRESS-X is defined by ISO 10303-14 within the EXPRESS language family.

Extension

In the step-wise development approach of the IFC, an extension extends the IFC Object Model to cover a new domain. An extension is defined by IFC model development projects.

 F

Facility

A physical structure or installation including related site works, serving one or more main purpose

Feature

A region of interest on the surface of a part. Features may form a hierarchy with, on the highest level, pattern features. Pattern Features may be placed in a hierarchy of sub-patterns, but end with compound features. Compound features may also be placed in a hierarchy of sub-compound features, which end with so-called primitive features. The latter type of features cannot be decomposed further.

File Based Data Exchange

Data exchange that happens using files between the sending application and the receiving application.

Formal

Described in an unambiguous, systematic way.

Format

A structure and syntax in which data is encoded.

Full Model Exchange

A form of data exchange where the whole product model is exported into an exchange file.

Note: See also Partial model exchange.

Function

In general, the behavior of a thing.

FP

Functional Part

A unit of information within an exchange requirement that may be fully described and modeled in its own right.

 G

Generalization

In information modeling, creation of a more generic class that captures the common characteristics of the more specific classes.

Creation of a supertype for a number of entity types (subtypes) such that the supertype captures the common attributes and constraints of the subtypes, which then do not need to be defined individually in the subtypes because they are inherited from the supertype.

GML

Geographic Markup Language

XML-based language for describing and encoding geospatial information. An application of XML, a specification developed by members of the Open GIS Consortium.

Global Rule

An EXPRESS constraint defined outside of entity types, and which may define constraints applicable to a number of entity types and their instances.

GUID

Globally Unique Identifier

A pseudo-random number used in software and database applications. While each generated GUID is not guaranteed to be unique, the total number of unique keys (2128 or 3.40282366×1038) is so large that the probability of the same number being generated twice is very small.

The term GUID usually references Microsoft's implementation of the Universally Unique Identifier (UUID) standard, however, many other software developments and standards including IFC use the term GUID.

 H

Hierarchy

A ranking or ordering of abstractions. The two most common hierarchies in a complex system include its class structure (the "kind of" hierarchy) and its object structure (the "part of" hierarchy), hierarchies may also be found in the module and process architectures of a complex system. Hierarchy is one of the fundamental elements of the object model.

Human Interpretable

Data representation without well defined semantics (meaning, interpretation rules) and therefore not computer interpretable. Example: interpretation of traditional or computer generated documents e.g. drawings are based on human intuition and experience.

 I

IAI International

A legal entity registered as a ‘company limited by guarantee’ (i.e. not profit distributing) within the United Kingdom and owned by the various IAI Chapters and that acts as the focus for matters of ownership, copyright and intellectual property rights in respect of materials produced by or assigned to an IAI entity for global distribution.

ICT

Information and Communication Technology

IDEF0

ICAM Definition Language 0

A modeling method for process (or function) modeling in which the processes are describes as hierarchical subprocesses which are composed of activities (or functions) and material and information flows between the activities. These can be inputs or outputs for the activities. The activities may also have control and mechanism, e.g. an actor or tool, that performs the activity.

IDEF1X

ICAM Definition Language 1X

Data modeling method that has a close relationship to the relational model of relational databases.

Identifier

An attribute with a unique value.

An unambiguous reference to a resource within a given context. Recommended best practice is to identify the resource by means of a string or number conforming to a formal identification system. Formal identification systems include but are not limited to the Uniform Resource Identifier (URI) (including the Uniform Resource Locator (URL)), the Digital Object Identifier (DOI) and the International Standard Book Number (ISBN).

Identity

The nature of an object that distinguishes it from all other objects.

IFC Exchange Format

An exchange format for IFC product data.

There are two alternative exchange formats for IFC product data, the one is based on ISO the 10303-21 standard (so-called IFC Part-21 format), and the other on XML (ifcXML).

IFC Object Model

A conceptual model for AEC/FM interoperability.

The IFC Object Model is primarily represented by the IFC EXPRESS schema from which and ifcXML schema representation is also defined.

IFC Platform

The central subset of IFC Object Model that is frozen for a number of years, and on the top of which new extensions will be defined.

IFC Specification

The whole of IFC Release documentation that includes IFC Object Model in EXPRESS/EXPRESS-G, the semantic definitions and explanations, and IFC Property Set definitions.

IFC Toolkit

A software library or component that provides software developers for the functionality of reading and writing IFC product models together with a data access interface for accessing the IFC product data.

IFC Toolkits are used in implementing IFC interfaces or pre- and post-processors for applications.

IFC-Model

Note: See IFC Object Model.

IfcXML

Definition of IFC Object Model using XML schema language.

IfcXML enables exchange of IFC product data in XML format.

ifcXML data specification defines (using XML schema language) the same data content as the IFC EXPRESS schema, only the specification language is different. ifcXML specification enables exchange of IFC product data in XML format.

Implementation

In the IFC context, an IFC implementation means application’s capability to create and use, and import and export IFC Project data.

ISG

Implementers Support Group

A group within IAI that provides a forum for co-operation and support in implementing IFCs.

IFC

Industry Foundation Classes.

An international specification for product data exchange and sharing for AEC/FM. IFC enables interoperability between the computer applications for AEC/FM. A subset of IFC is approved as ISO/PAS 16739.

Information

Data that has been interpreted, translated, or transformed to reveal the underlying meaning.

Note: See also data, knowledge

IDM

Information Delivery Manual

Information Flow

In process modeling, exchange of information between activities such that output information from one activity acts as an input information form another activity.

IFD

Information Framework for Dictionaries

An international development of an object library for the AEC/FM industry that is compatible with IFC and can be used to get more detailed information in and out of your construction design.

An alternative identity for the conceptual model within ISO 12006 Part 3

Information Management

Integrating information standards, processes, systems, and technology to enable the exchange of information among providers and users in order to support the management objectives of an organization.

Information Model

Formal definition of information, which defines the elements of information and their relationships.

A formal model of a bounded set of facts, concepts or instructions to meet a specified requirement.

Synonym for conceptual model

Inheritance

A specialization / generalization relationship between entity types, the supertype and subtype(s), by which the subtype inherits all the attributes and constraints from the supertype. Additionally subtype may have more specific attributes and constraints.

Inheritance Hierarchy

The (hierarchical) relationship structure between entity types formed through their inheritance relationships (Is-a).

Note: Synonym for the term Class hierarchy.

IGES

Initial Graphics Exchange Specification

A neutral file format for the exchange of geometry data between CAD systems. The first versions of IGES were standardized as ANSI Y14.26M in 1979.

Instance

A unique instantiation of an entity type. I.e. creation of a unique instance of an entity type such that the attributes of and constraints on the instance are defined by the entity type, and each instance has its own identity and values for their attributes.

Instantiation

Creation of instances of an entity type.

IAI

International Alliance for Interoperability

An open consortium to develop, promote and for implementation support of IFC.

ICIS

International Construction Information Society

An association of organizations that provides national master specification systems and/or cost information systems for the construction industry.

IC

International Council

The highest decision making body within the IAI. Each IAI Chapter has representatives in IC.

ISO

International Organization for Standardization

A network of the national standards institutes of 157 countries.

ISO is a non-governmental organization: its members are not delegations of national governments. Many of its member institutes are part of the governmental structure of their countries, or are mandated by their government. Other members have their roots uniquely in the private sector, having been set up by national partnerships of industry associations.

Therefore, ISO is able to act as a bridging organization in which a consensus can be reached on solutions that meet both the requirements of business and the broader needs of society, such as the needs of stakeholder groups like consumers and users.

Whatever the country, whatever the language, the short form of the organization's name is always ISO

ITM

International Technical Management

The technical decision making and coordination body within the IAI. Each IAI Chapter has representatives in ITM.

Interoperability

In general, the ability of systems to work together.

Ability of computer applications to exchange, share and utilize digital product /  project data within e.g. AEC/FM projects and over the life cycle of buildings and building information.

Inverse Relationship

A definition of a relationship in an inverse direction. The inverse relationship defines a name and cardinality for a relationship in the inverse direction.

ISO 10303 Standard

ISO 10303 Product data representation and exchange standard.

An international standard that has defined the basis for product data technologies, and product data exchange standards for a number of industry sectors.

ISO 10303-11 Language

Formal specification of the EXPRESS data definition language

ISO 10303-21 Format

A data exchange format defined by ISO 10303-21 for the exchange of data encoded according to the EXPRESS data definition standard. Also termed ‘Part 21 format’.

ISO 12006-2

A standard that defines a Framework for classification of information.

ISO 12006-2:2001 is defined by Working Group 2 of ISO TC59/SC13

ISO 12006-3

A standard that specifies a language-independent information model which can be used for the development of dictionaries used to store or provide information about construction works. It enables classification systems, information models, object models and process models to be referenced from within a common framework.

ISO 12006-3:2007 is defined by Working Group 3 of ISO TC59/SC13

ISO TC59/SC13

The ISO Technical Committee/Sub-Committee concerned with the ‘Organization of information about construction works’

ISO TC184/SC4

The ISO Technical Committee/Sub-Committee concerned with ‘Industrial Data’.

An international standardization subcommittee that works on a family of standards for representation and exchange of industrial data. Among other things ISO 10303 standard is developed within this subcommittee.

Note: IFC uses base technologies (e.g. EXPRESS and ISO 10303-21 format) from the ISO 103030 standards developed by ISO TC184/SC4 and adapt concepts from a number of standards particularly within the generic resources set (ISO 10303-4x series).

ISO/PAS 16739

A subset of IFC 2x specification that has an ISO Publicly Accessible Standard status.

IRD

Issues and ResolutionsDatabase

A database of IFC Object Model issues resulting from reviews and IAI Model Support Group resolutions against the issues.

 K

Key Attribute

One attribute or several attributes which provide a unique identification of an entity in a relational database.

Knowledge

Information from multiple domains that has been synthesized, into meaning or understanding that was not previously known.

Knowledge Management

Promoting, coordinating, and facilitating knowledge synthesis, preservation, processes, production and exchange in order to support the strategic goals of the organization.

 L

Lifecycle

All of the different phases an object goes through from the first stages in the programming of a building to the demolition.

List

A type of EXPRESS aggregate that can vary in size and in which the elements are indexed by order.

Long Form

In EXPRESS modeling, a form of a single schema which is a result from resolving the interfaces of multiple modular interrelated schemas.

 M

Mapping

The process of converting a data set from one form (source) to another form (target). Both source and target may be defined by different schemas.

Mapping Processor

Synonym for term Converter.

Mapping Specification

Description of the mapping between the source form and the target form.

Meta Model

Model that describes other models.

Metadata

Information about data, including the format of the data element, which application system owns it, where it is located, how it should be used. Metadata is the global information about what data exists across the enterprise and the standards that apply to that data.

Method

Message from another object triggers execution of a method by the receiving object in an object-oriented system.

Methodology

A study of scientific methods.

Middleware

Software and application program interfaces that serve as intermediaries among application programs and services,

Middleware insulates programmers from the complexities of the communication architecture, such as network protocols.

Model

An abstraction and representation of the relevant characteristics of the target system for a purpose.

Model DevelopmentProject

A project within IAI the purpose of which is to capture information requirements and results into an extension model to extend IFC into a new domain.

Model Server

A computer application that provides a shared model repository, model management functionality and a data access interface to product/project models for multiple, concurrent client applications over the net.

Model-Based

An approach, e.g. for AEC/FM computer applications, where the target system (e.g. building) is represented by a model which then is used as a basis for analysis, creation of presentations, reports, and exchange of data.

MSG

Modeling Support Group

A group, within IAI, of technical experts that are responsible for the IFC Object Model and Specification integration, development and maintenance.

Multiple Inheritance

A form of inheritance where an entity type (class) inherits from more than one direct supertypes.

 N

nD

n-Dimensional

A term used to describe an arbitrary number of dimensions of model visualization beyond the 5 dimensions represented by space, time and cost.

Nesting

In IFC, a type of composition where the composite element is a composition of elements of the same type.

Neutral Form

A form of data that is independent of individual computer applications. Typically, neutral forms are defined by standards or other open specifications.

 O

Object

A collection of data that is handled in applications as a single unit.

In object or product modeling things are modeled as objects, that have attributes (or properties) and relationships to other objects.

E.g. the building elements of a building may be modeled as objects that have properties and relationships to other building elements.

Note: Sometimes generally speaking the term object may mean either a class or an instance of a class. If it is necessary to explicitly make the distinction between the two, the latter terms should be used.

OMG

Object Management Group

A consortium originally aimed at setting standards for distributed object-oriented systems, and now focused on modeling (programs, systems and business processes) and model-based standards.

Responsible for the Unified Modeling Language (UML)

OO

Object Oriented

A modeling / programming paradigm in which things are modeled / implemented as objects, their relationships (and messaging between the objects).

Occurrence Object

A unique occurrence of an object that shares the common characteristics of a type object with other similar occurrence objects, but all the occurrence objects have their own existence and possible other characteristics, such as location. See also ‘Type object’ for comparison.

Ontology

Enable communication between computer systems.

The key ingredients of an ontology are a vocabulary of basic terms and a precise specification of what those terms mean.

OGC

Open Geospatial Consortium

A non-profit, international, voluntary consensus standards organization that is leading the development of standards for geospatial and location based services. The GML standard is particularly important in this regard.

OGC and IAI have a liaison agreement

Open Standard

A standard that is:

·         created in an open, international, participatory industry process

·         freely distributed and openly accessible

·         technology neutral: i.e. its use must not be predicated on any proprietary technology or style of interface.

Open System

A system with standardized interfaces between its components, and the internal structure of the components are independent of other components.

A system that interoperates through open interfaces, protocols etc. developed and maintained in an inclusive, open consensus process. Open systems promote application portability, scalability, interoperability, diversity, manageability, extensibility, compatibility with legacy components, and user portability.

Optional Attribute

In EXPRESS, an attribute the value of which may be missing.

Note: If the attribute is not optional the value has to be always provided.

 P

Paradigm

A pattern or model.

Parameter

A variable used for controlling the value of a mathematical function.

Parser

A tool used to interpret a text according to a specific language that is described by a set of syntactic rules. The parser finds the language elements in the text and signals any syntactic error. Parsers are usually part of interpreters and compilers.

Partial Model Exchange

Exchange or export / import of a product model which is only a subset of the total model.

Partial model exchange brings about a set of issues, like change and version management, and referencing objects that are not part of the exchange, to be addressed as comparison to full model exchange.

Post-Processor

A software module that make a conversion from a neutral form to the software's internal representation form.

Note: Here, pre/post processing is defined from the viewpoint of the data exchange file.

Pre-Processor

A software module that make a conversion from the software's internal representation form to an external form, which may be defined by an data exchange standard.

Note: Here, pre/post processing is defined from the viewpoint of the data exchange file.

Presentation

Defines how the characteristics of an object are presented on a computer screen or in documents.

Process

A system of activities, the material and information flows between the activities, activity resources, and process control to produce a result.

Process Breakdown

The decomposition of the process into subprocesses and activities.

Process Chart-Method

A process modeling method in which a process is described as activities and material and information flows between the activities. Characteristic for the method is that each participating actor has its own "swim lane" for its activities.

Process Model

A model that represents the relevant characteristics of a process for a defined purpose.

Product Data

A representation of information about a product in a formal manner suitable for communication, interpretation, or processing by human beings or by computer applications.

Computer interpretable data about product and related things.

For example, information about a building and the construction project stored into an exchange file in IFC format.

Product Data Definition

A formal definition of product data.

Product data model is an example of product data definition.

Product Data Model

An information model for product data.

A formal specification of product data.

For example, IFC Object model is a product data model defined for AEC/FM product data.

Product Data Technology

A set of IT methods, models, standards, toolkits and applications that to support the Information processes throughout the life cycle of a product.

Product information

Facts, concepts or instructions about a product.

Product Library / Part Library

A digital library of product information that computer applications can utilize in product modeling.

For example, furniture manufacturer's product information library for furniture, that the designers can access via Internet, and use the product information as part of the building model created using a CAD-application.

Product Model

An instantiation of a product data model.

A product model of a specific building represents product data about the building in a form that is defined by a product data model.

For example, model of a building stored into an exchange file in IFC format.

Product Modeling

An art and science that deals with modeling and representation and exchange of products and product information in computer interpretable form.

Product Structure

Describes the decomposition of a product from its components.

Project

A unique set of work, with limited duration, which has a goal and resources to aim for the goal.

Project Data

Computer interpretable data about construction projects and the resulting products, the buildings.

Project Database

A database for project specific data.

Property

In general, properties represent qualities and characteristics of something.

In IFC, properties are a generic mechanism and data-driven way of representing characteristics of objects. i.e. the properties have a name, a value, and may be related to objects.

Property Set

Within IFC, a grouping of properties that belong together based on some principle, like viewpoint or lifecycle stage.

PSDML

Property Set Definition Markup Language

An XML based encoding for presentation of IFC property sets.

Protocol

The agreed-on rules that computers rely on to talk among themselves.

 Q

Quantity Data

Data that describes quantities like pieces, areas or volumes and is derived typically from the shape data of individual objects. Quantity data is often summarized per construction type.

E.g. The area and volume of a wall derived from its basic dimensions, or the total area of walls of same construction type.

 R

Reference Model

A model that is sufficiently generic and has enough degrees of freedom so that it applies to various, more specific purposes.

Referential Integrity

A condition of a database according to which in references all the referred objects also exists.

This means that there are no conflicts (e.g. missing records) in the reference structure of database content.

Relationship

An association between objects.

Repository

A storage of data.

Representation

Defines how the characteristics of the object are represented.

2D, 3D, solids, wire frames etc. are examples of representations.

RFI

Request For Information

Request for information in connection with a process or product.

RFP

Request For Proposal

Request to a vendor soliciting a proposal for materials, goods, software or services.

RDF

Resource Description Framework

A family of World Wide Web Consortium (W3C) specifications originally designed as a metadata model using XML but which has come to be used as a general method of modeling knowledge, through a variety of syntax formats (XML and non-XML).

The RDF metadata model is based upon the idea of making statements about resources in the form of subject-predicate-object expressions, called triples in RDF terminology. The subject denotes the resource, and the predicate denotes traits or aspects of the resource and expresses a relationship between the subject and the object. For example, one way to represent the notion "The sky has the color blue" in RDF is as a triple of specially formatted strings: a subject denoting "the sky", a predicate denoting "has the color", and an object denoting "blue".

This mechanism for describing resources is a major component in what is proposed by the W3C's Semantic Web activity: an evolutionary stage of the World Wide Web in which automated software can store, exchange, and use machine-readable information distributed throughout the web, in turn enabling users to deal with the information with greater efficiency and certainty. RDF's simple data model and ability to model disparate, abstract concepts has also led to its increasing use in knowledge management applications unrelated to Semantic Web activity.

Rule

In EXPRESS, a way to represent constraints for information based on an EXPRESS model.

The rules may be entity type specific (WHERE RULE) or address a group of entity types (GLOBAL RULE)

 S

Schema

A model that defines representation of information.

In EPXRESS, a schema is a unit or module within the whole EXPRESS model that addresses a specific subdomain of the model. Schemas of an EXPRESS model may be related to each other via schema interfaces.

Schema Interface

Definition of relationships between interrelated schemas. Schema interface defines what types are used or referenced from one schema to another.

Select Type

An EXPRESS data type that defines alternative data types as its select items.

Semantics

Definition of meaning.

Semantic Web

A project to create a universal medium for information exchange by putting documents with computer-processable meaning (semantics) on the World Wide Web.

Set

A type of EXPRESS aggregate that can vary in size, in which the elements are not indexed by order, and the elements are unique (i.e. the same instance cannot occur twice in a set).

Shape Data (dimensional data)

Data that defines the shape of an object e.g. the length, width and height of a wall.

Short Form

A form of an EXPRESS model which is represented by multiple interrelated schemas. Each schema may address a specific subdomain of the model's total scope.

SOAP

Simple Object Access Protocol

A lightweight XML-based messaging protocol used to encode the information in Web service request and response messages before sending them over a network.

SOAP messages are independent of any operating system or protocol and may be transported using a variety of Internet protocols, including SMTP, MIME, and HTTP.

Simple Type

Simple types are the in-built basic data types within the EXPRESS language.

The EXPRESS Simple types are: generic, number, integer, real, string, boolean, logical and binary data types.

Single Inheritance

A form of inheritance where an entity type (class) may have only a single supertype.

Software

All or part of the programs, procedures, rules, and associated documentation of a data processing system.

Software is an intellectual creation that is independent of the medium on which it is recorded.

Specialization

Creation of a subtype for an entity type (the supertype) such that the subtype inherits all the attributes and constraints from the supertype, but the subtype may define its own specific attribute and constraints.

SPF

SPF-Format

STEP Physical File Format.

State

The current set of values of the properties (or attributes) that define an object (i.e. an occurrence of an entity).

State may also be considered as a ‘memory’ that may be changed by sending messages to the object.

SDAI

STEP Data Access Interface

A data access interface designed for repositories containing data configured according to an EXPRESS schema.

STEP

Standard for The Exchange of Product model Data.

A set of international standards under the designation ISO 10303.

Subtype

In the entity type inheritance relationship the more specific entity type that inherits properties from its supertype. Additionally the subtype may define its own specific properties.

Supertype

In the entity type inheritance relationship the more generic entity type that may have a number of more specific subtypes.

Symbol

Abstract graphical representations of objects, often used in CAD and CADD systems.

A symbol is also a term in the language to represent a concept or an object in the object oriented world.

Syntax

Definition of elements of and a grammar for a format.

System

An integrated whole that functions through the interrelationships between its components.

 T

Task

A piece of work that typically is planned and scheduled as part of a project work and time schedule.

Taxonomy

The science of classification according to a pre-determined system, with the resulting catalogue used to provide a conceptual framework for discussion, analysis, or information retrieval.

TAG

Technical Advisory Group

A group within IAI for advising IAI in IFC long term strategies and developments.

Term

The name corresponding to a concept.

Note: "Quadlet": Concept – term - definition - referent

Test case

An IFC model Instantiation as an IFC exchange file for certification purposes.

In the certification process the candidate applications are tested e.g. using the test cases.

To-Be Process

The future (goal) state of a process.

Note: In comparison, see As-is process.

Topology

Connectivity of elements that make up the representation of an object.

Type

Generic term for simple types, defined types and entity types.

Type Object

An object that represents the common properties shared by a number of occurrence objects.

Note: See also occurrence object.

 U

UML

Unified Modeling Language

A general-purpose modeling language that includes a standardized graphical notation used to create an abstract model of a system. It is extendable using profiles and stereotypes.

Adopted as a de facto standard by the Object Management Group.

URL

Uniform Resource Locator

A type of identifier that is an address that specifies the location of a file on the Internet

URN

Uniform Resource Name

A type of identifier for a resource on the Internet that is a globally unique, location-independent, persistent name.

Unique List

An extension of the EXPRESS LIST aggregate that can vary in size, in which the elements are indexed by order, and the elements are unique (i.e. the same instance cannot occur twice in a set).

Uniqueness Rule

A rule within EXPRESS language that defines that a value of an attribute or combined values of attributes have to be unique for each instance of an entity type.

Upward Compatibility

A type of compatibility in which the data files based on an earlier specification release are compatible with data files based on a later specification release.

 V

WHERE Rule

In EXPRESS; a rule within the context of an entity type that defines constraints for all the instances of the entity type.

View

In general, a subset of, or perspective to the totality from a specific viewpoint or specific purposes.

In IFCs, a defined subset of IFC Object Model that a number of implementers have agreed to support in their implementations.

Virtual Environment

A data set describing an environment based upon real-world or abstract objects and data that can be used as a representation of the real world.

Vocabulary

A set of terms relevant for a certain domain

 W

OWL

Web Ontology Language

A language for defining Web ontology’s and their associated knowledge bases

Web Services

Self-contained, self-describing, modular applications that can be published, located, and invoked across the Web. Web services perform functions that can be anything from simple requests to complicated business processes. Once a Web service is deployed, other applications (and other Web services) can discover and invoke the deployed service.

WSDL

Web Services Description Language

An XML-formatted language used to describe a Web service's capabilities as collections of communication endpoints capable of exchanging messages. WSDL is an integral part of UDDI, an XML-based worldwide business registry. WSDL is the language that UDDI uses.

Workflow

The automation of a business process, in whole or part, during which documents., information or tasks are passed from one participant to another for action, according to a set of procedural rules.

Workflow Management System

A system that defines, creates and manages the execution of workflows through the use of software which is able to interpret the process definition, interact with participants and invoke IT tools.

XML Schema

A definition of representation of information using XML schema language. XML schema defines representation of information for specific purpose, within specific domain.

XSG

XML Support Group

A group that existed within IAI, to coordinate ifcXML work. This group is not currently operational. ifcXML development activities are now within the scope of the IAI Model Support Group.

XML

eXtensible Markup Language

A language for defining and exchanging structured, computer interpretable information. It provides a method for both the definition of information, and the encoding of data based on the definition into an exchange format.

Note: XML schema language is an alternative method to EXPRESS data specification language to define product data models like the IFC model, and ifcXML is an alternative data exchange format to the IFC ISO 10303-21 exchange format.

XSLT

eXtensible Style Language Transformation

The language used in XSL style sheets to transform XML documents into other XML documents. An XSL processor reads the XML document and follows the instructions in the XSL style sheet, then it outputs a new XML document or XML-document fragment. This is extremely useful in e-commerce, where the same data need to be converted into different representations of XML. Not all companies use the exact same programs, applications and compu

ter systems.