5. Glossary

To complete the glossary below, please refer to the bimdictionary.com website, which lists the terms and definitions of the various directives and standards.

AIM (Asset Information Model)

The asset information model refers to “geometric models, structured data and documentation” exchanged during building operation.

AIR (Asset Information Requirements)

Asset Information Requirements (AIR) are the deliverables required by the Owner to manage the building during its operation (e.g. space nomenclatures, space descriptions, equipment technical data, warranty information, maintenance schedules, etc.).

BCF (BIM Collaboration Format)

BCF is a format for communicating messages describing problems discovered on the digital mockup. It can be used to transfer comments relating to an object in a mock-up between the various parties involved in a project.

BEP (BIM Execution Plan)

The BIM Execution Plan (BEP) is an updated and completed version of the PBB, based on the response provided by the project management team. It then takes on a contractual value and becomes the reference document on which everyone can rely at any time, so that they know what is expected of them and what they can expect from others. The methodology for drawing up a BEP therefore follows the same themes as the PBB, while supplementing it with the directives that will actually be implemented during the project:

  • Project description and final BIM uses to be implemented
  • Definition of the complete organizational context (with a detailed description of roles and competencies)
  • Summary schedule of milestones and deliverables, including intermediate deliverables (TIDP)
  • Work and exchange processes based on usage and milestones
  • Summary table of final GID levels by object and milestone/phase (EIR)
  • Definition of the technical context and the final means of exchange (software and exchange formats, naming conventions, modeling requirements, etc.).
  • Other specific requirements (e.g. model checking, georeferencing, model size, etc.).

EIR (Exchange Information Requirements)

The “Exchange Information Requirements” (EIR) are the definition of the right “level of information need” at each milestone, and who will be responsible for it.

IFC (Industry Foundation Class)

The IFC format is an exchange format created to ensure interoperability between software programs, enabling the universal description of the “elements” that make up a building throughout its life cycle (design, construction, operation) and from different points of view (architectural, structural, thermal, estimating, etc.). IFCs are included in a file whose format is predefined according to an international standard (STEP) ISO 10303-21.


The ability to communicate, run programs or transfer data between the various software programs handling the digital mock-up, so that the user needs to know little or nothing about the specific characteristics of each software program used by the other participants.

Computerized Maintenance Management System (CMMS)

A CMMS is used to support building maintenance departments such as equipment management (inventory, location, technical information), maintenance task management (corrective or preventive), facility safety management for maintenance work, purchasing and inventory management, personnel management and activity planning. Some of the information required for these services (e.g. information on equipment and its location) can be extracted from a digital mock-up.

LOD/LOI) – « Level of… »

The acronym “LOD” was first used in 2004. It stood for “Level of Detail”, and established the progressive reliability of information over a period of time. In 2008, the AIA (American Institute of Architects) created the “BIM Protocol”, which became the reference document worldwide and introduced 5 levels (100 to 500) of “LOD”, the same acronym for a different definition: Level of Development. Each country was able to appropriate this concept and create its own specifications. Among the best-known and most widely recognized, the Anglo-Saxon approach (formalized in standard PAS1192-2, published in 2013) refers to a Level of Definition whose value ranges from 1 to 7 and is broken down into two sub-levels: “LOD” (Level of Detail, for graphic content) and “LOI” (Level of Information, for non-graphic content). Today, ISO standards are being drafted to standardize these approaches. In particular, they introduce the more generic concept of Level of Information Need (see definition in this glossary).

Digital mock-up

Mock-ups are the digital geometric files produced and fed into the design, execution and management of a building. They enable visualization, control, simulation (thermal, acoustic, etc.) and extraction of informed quantities and deliverables.

MIDP (Master Information Delivery Plan)

General schedule for delivery of the various information (deliverables) expected by the project owner at the different phases of the project.

TIDP (Task Information Delivery Plan)

Detailed schedule for the delivery of different information (deliverables) between project team members and with specific delivery milestones (MIDP breakdown).

« nD » or « xD »

Adding information of different kinds and in successive layers to a 3D model is commonly referred to as adding new “dimensions”:

  • 4D (added implementation times) to support Planning
  • 5D for managing quantities and associated costs (adding prices)
  • 6D for facilities and asset management (addition of maintenance ranges)
  • Etc.

A consensus is emerging among the various approaches to the definition of 4D and 5D. Beyond that, there is no universal reference: information is added according to need, thus multiplying the “xD” manipulated (a dimension corresponds to an added piece of information (or set of pieces of information)).

Level of need for information

The level of information need defines the quality of each piece of information to be delivered in terms of granularity, in order to serve the purpose for which the information is required, and no further. There are then a number of measurement quantities, which may be complementary but independent, but which make it possible to define the granularity and level of information requirement that needs to be defined.

GID level

The GID level is the level of information requirements defined and adopted in Luxembourg: it is the sum of three levels of granularity relating to Geometry (100/200/300/400/500), Information (10/20/30/40/50) and Documentation (1/2/3/4/5). In this way, the GID concept takes into account all the data required and shared during a project: geometric models, structured data and documentation.

PBB (Project BIM Brief)

The Project BIM Brief (PBB) describes the client’s expectations regarding the organization of a BIM project. Topics covered include :

  • Description of BIM objectives and recommended/required uses of BIM
  • Definition of the pre-established organizational context on the project owner’s side (with a detailed description of roles and competencies)
  • Definition of information requirements according to milestones (PIR / AIR / MIDP)
  • Summary table of recommended GID levels by object and phase (EIR)
  • Definition of the technical context and recommended means of exchange (software and exchange formats, naming conventions, modeling requirements, etc.).
  • Defining available resources
  • Other special requirements


A process is a sequence of production tasks punctuated by exchanges of information (including deliverables) and validation stages. Formalizing a process enables us to structure the tasks of the various players involved, and to assess how well they are being carried out.

PIM (Projet Information Model)

The project information model refers to the “geometric models, structured data and documentation” exchanged during project implementation.

PIR (Project Information Requirements)

Project Information Requirements (PIR) are the deliverables required during the construction phase by the Owner to manage his project and make decisions (models, plans and other graphic deliverables for architectural assessment of the project; study reports for building performance assessment; schedule tracking; budget tracking, etc.).

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