Why These Terms Matter

BIM and CAD workflows run on a vocabulary that is easy to mishear as jargon but actually encodes real contractual and technical meaning. When a spec calls for "LOD 350" or a BIM execution plan requires a "federated model," those phrases determine what a design team must model, how liability is assigned, and whether a clash-detection report holds up in a coordination meeting. Terms like "level of development," "workset," and "family" have precise, standard-defined meanings that differ from how the words are used casually — and getting them wrong can mean re-modeling a discipline's work or missing a coordination deadline.

This glossary covers 55 of the most frequently used terms across BIM authoring (Revit), 2D drafting (AutoCAD), coordination (Navisworks, BIM 360/ACC), and the open data standards (IFC, COBie, ISO 19650) that tie disciplines together on a shared digital model. Definitions are written in plain language with the standard, software, or convention each term comes from.

A

Annotation — Revit / general CAD
Non-geometric information added to a drawing or model view for documentation purposes — dimensions, text notes, tags, keynotes, and symbols. Annotations are view-specific in Revit (they appear only in the view where they were placed) as opposed to model elements, which exist in 3D space and appear in every view that shows that location.
Architectural, Engineering, and Construction (AEC) — industry term
The umbrella term for the building design and construction industry, used to describe software, standards, and workflows that serve architects, engineers, and contractors collectively (as opposed to manufacturing or product design, which uses similar 3D tools but different conventions).
As-Built Model — construction/BIM handover
A BIM model updated after construction to reflect actual installed conditions, including contractor-initiated changes, field revisions, and RFI resolutions that deviate from the design model. As-built models are typically a deliverable required at project closeout and form the basis for facilities management handover.
Autodesk Construction Cloud (ACC) — software platform
Autodesk's cloud-based common data environment that replaced BIM 360 as the primary platform for model coordination, issue tracking, document management, and field collaboration across the project team. Revit models are published to ACC for cloud worksharing and multi-firm coordination.
AutoCAD — software
Autodesk's general-purpose 2D and 3D CAD drafting software, historically the industry standard for construction documentation before BIM authoring tools became widespread. AutoCAD works with discrete lines, arcs, and blocks rather than parametric, data-rich building elements — a wall drawn in AutoCAD is just geometry, while a wall drawn in Revit knows it is a wall with a type, height, and material makeup.

B

Bidirectional Associativity — parametric modeling concept
The property of parametric BIM software where a change made in any view (plan, section, elevation, schedule) automatically updates every other view and the model itself. Moving a wall in a floor plan updates the wall in every section, elevation, and 3D view without manual re-drafting — the defining advantage of BIM over traditional CAD.
BIM Execution Plan (BEP) — project management document
A formal document, typically developed at project kickoff, that defines how BIM will be used on a project: model authoring responsibilities by discipline, level of development requirements by phase, coordinate systems, file naming conventions, clash detection protocols, and model exchange procedures. ISO 19650 formalizes the BEP as a required deliverable, often split into a pre-appointment BEP (proposed approach) and a post-appointment BEP (confirmed approach after contract award).
BIM 360 — software platform (legacy)
Autodesk's earlier cloud collaboration platform for BIM coordination, document management, and field tools, largely superseded by Autodesk Construction Cloud (ACC) as of the mid-2020s, though the name persists in common industry usage and in some still-active projects.
Building Information Modeling (BIM) — industry-wide methodology
A process for creating and managing digital representations of physical and functional characteristics of a building, where the 3D model carries data (materials, quantities, performance properties, manufacturer information) in addition to geometry. BIM is distinct from 3D CAD in that BIM elements are "intelligent" objects — a door in a BIM model knows its fire rating, hardware set, and manufacturer, not just its shape.

C

Clash Detection — coordination process
The automated process of checking multiple discipline models (architectural, structural, mechanical, electrical, plumbing, fire protection) against each other to identify physical conflicts — a duct running through a structural beam, a pipe intersecting a wall. Performed in software like Navisworks or the clash-detection modules of ACC/BIM Collaborate, clash detection runs are typically scheduled weekly during design development and construction documents to catch conflicts before they reach the field.
Clash Grouping — Navisworks term
The practice of consolidating multiple individual clash results that stem from the same root cause (e.g., an entire duct run crossing a beam line at ten points) into a single reportable issue, so coordination teams resolve the underlying design conflict once rather than tracking ten redundant clash tickets.
Common Data Environment (CDE) — ISO 19650 term
The single shared source of information for a project — a cloud platform (ACC, BIM 360, Trimble Connect, or similar) where all project models, drawings, and documents are stored, versioned, and shared among the project team. ISO 19650 defines the CDE workflow states as Work in Progress (WIP), Shared, Published, and Archive.
COBie (Construction Operations Building Information Exchange) — data exchange standard
A structured spreadsheet-format data standard (built on a defined set of worksheets and column headers) used to transfer non-geometric asset data — equipment types, model numbers, warranties, maintenance schedules, spatial locations — from the design/construction BIM model to a facilities management or CMMS (computerized maintenance management system) at project handover. COBie deliverables are increasingly required by federal and institutional owners as a contract requirement.
Coordinate System / Shared Coordinates — Revit/civil coordination term
The common origin point and orientation that all discipline models must share so that a mechanical model, structural model, and architectural model align correctly in 3D space when linked together. Establishing shared coordinates early — usually tied to a civil survey point — prevents models from being offset or rotated relative to each other during coordination.
Coordination Model / Federated Model — coordination term
A composite model created by linking together the individual discipline models (architectural, structural, MEP, civil) into a single navigable environment, typically in Navisworks or a similar viewer, used for clash detection, spatial coordination, and construction sequencing review. The federated model is not usually edited directly — each discipline continues to edit its own source model, which is then re-linked or re-published to update the federation.

D

Digital Twin — operations/facilities term
A live, continuously updated digital model of a physical building or asset that is connected to real-time data from building sensors, BMS points, or IoT devices, used for ongoing operations, energy analysis, and predictive maintenance — distinct from a static as-built BIM model, which is a snapshot rather than a live-synced twin.
Drawing Set — construction documentation term
The complete package of 2D construction drawings (plans, sections, elevations, details, schedules) generated from the BIM model or drafted directly in CAD, issued for permit, bidding, or construction. In a BIM workflow, sheets are generated as views of the underlying model rather than drawn independently, which is what enforces bidirectional associativity between the model and documentation.
Dynamo — visual programming tool
A visual (node-based) programming environment built into Revit that lets users automate repetitive modeling tasks, generate complex parametric geometry, and extract or modify model data without writing traditional code. Common Dynamo use cases include batch-renaming views, placing families along a curved path, and auto-populating room data from a linked spreadsheet.

E

Element — Revit term
Any individual component placed in a Revit model — a wall, door, window, duct, or piece of furniture. Elements are instances of families and carry both geometric and non-geometric (parameter) data.
Exchange Information Requirements (EIR) — ISO 19650 term
A document produced by the project owner or client that specifies what information is required from the BIM model at each project stage — level of information need, file formats, and purposes the data will serve (cost estimating, code review, facilities management). The EIR sets the requirements that the BIM Execution Plan is written to satisfy.

F

Family — Revit term
A template or class of building component in Revit that defines a set of parameters (dimensions, materials, behavior) and geometry, from which specific instances ("types") are placed in a model — for example, a "Door — Single Flush" family might have types for 30", 32", and 36" widths. Families are the building blocks of a Revit model and can be system families (walls, floors, roofs, built into the software) or loadable families (doors, furniture, equipment, created and shared as external .rfa files).
Federated Model
See Coordination Model.
File Naming Convention — BEP/ISO 19650 term
A standardized structure for naming model and drawing files (e.g., Project-Originator-Volume-Level-Type-Role-Number) so that files from multiple firms can be organized, filtered, and version-controlled consistently within a common data environment. ISO 19650 defines a specific recommended naming schema that many BEPs adopt or adapt.

G

Grids and Levels — Revit project setup terms
Reference planes that establish the coordinate framework of a Revit model: grids are vertical reference planes (usually labeled with numbers and letters) used to locate columns and structural elements in plan, while levels are horizontal reference planes that define floor-to-floor heights and generate the floor plan views associated with each story.

H

Host — Revit term
The element that another element is physically attached to and depends on for its placement — for example, a wall "hosts" the doors and windows placed within it. Deleting or moving a host element affects everything hosted on it.

I

IFC (Industry Foundation Classes) — open data format, ISO 16739
A vendor-neutral, open file format for exchanging BIM data between different software platforms (Revit, ArchiCAD, Tekla, Bentley) without loss of the underlying object data. IFC is the standard used when a project team includes firms on different BIM authoring platforms, or when a model must be archived in a software-independent format for long-term owner access.
Instance Parameter — Revit term
A property of a Revit element that can be set individually for each placed instance of a family type, as opposed to a type parameter, which applies to every instance of that type simultaneously. Instance parameters are used for values that legitimately vary per-object, such as a room's finish schedule comment or a specific door's mark number.
Interference Check
Revit's native, lighter-weight clash detection tool, used for quick checks within a single linked model set before a full coordination review is run in Navisworks with the complete federated model from all disciplines.

L

Level of Development (LOD) — AIA/BIMForum standard
A standardized scale (100 through 500, in increments of 100, plus LOD 350 as a common intermediate milestone) describing how much geometric detail and reliable data a model element contains at a given project phase. LOD 100 is conceptual massing; LOD 200 is approximate geometry and quantity; LOD 300 is precise geometry suitable for construction documents; LOD 350 adds interface and coordination detail between systems; LOD 400 is fabrication-ready detail; LOD 500 is verified as-built condition. The BIMForum LOD Specification, published in coordination with the AIA E203 contract exhibit, is the industry reference for LOD definitions by element category.
Level of Information Need (LOIN) — ISO 19650-1 term
The international-standard successor concept to LOD, defined in ISO 19650, describing the geometric, alphanumeric, and documentation detail needed for a given use case rather than a fixed milestone scale — used increasingly on projects following UK/ISO BIM protocols alongside or instead of the US-centric LOD scale.
Linked Model — Revit/coordination term
An external model (from another discipline or another portion of the same building) attached, or "linked," into the current model for reference and coordination without merging the two files together — as opposed to importing, which embeds a static, non-updating copy. Linked models update automatically when the source file is reloaded, which is the mechanism that keeps multi-discipline coordination current.

M

Massing — early design term
Simplified, conceptual 3D geometry used in early design phases to study building form, site relationships, and program area before detailed modeling begins — corresponds roughly to LOD 100.
MEP (Mechanical, Electrical, Plumbing) — discipline grouping
The building systems disciplines that are typically modeled and coordinated together in BIM workflows because of their high potential for physical clashes with each other and with structure — ductwork, piping, conduit, and cable tray routing are the most common source of coordination clashes on a project.
Model Element Author (MEA) — BEP term
The party (discipline or firm) formally responsible for authoring, and therefore accountable for the accuracy of, a specific model element or system — defined in the BIM Execution Plan's model element table to establish clear ownership and avoid duplicate or conflicting modeling of the same building component by two firms.

N

Navisworks — software
Autodesk's model review and coordination software used to aggregate discipline models from multiple authoring platforms into a single federated model for clash detection, 4D construction sequencing (linking the model to a schedule), and quantity takeoff — the standard tool for the weekly BIM coordination meeting across the AEC industry.

O

openBIM — industry initiative
A vendor-neutral collaborative approach to BIM based on open standards (primarily IFC and BCF) rather than a single software vendor's proprietary format, promoted by buildingSMART International to ensure long-term data accessibility and multi-platform interoperability.

P

Parametric Modeling — core BIM concept
A modeling approach where element geometry and behavior are driven by defined parameters and relationships (dimensions, constraints, formulas) rather than being drawn as fixed, independent geometry — the core technical concept that makes Revit-style BIM software behave differently from AutoCAD-style drafting, since changing one parameter (like a floor-to-floor height) automatically updates every dependent element.
Phasing — Revit term
A Revit feature that assigns model elements to defined project phases (existing, demolished, new construction, future) so that a single model can generate accurate existing-conditions, demolition, and new-construction drawing sets from one coordinated dataset, rather than maintaining separate files for each phase.
Point Cloud — scan-to-BIM term
A dense set of 3D coordinate points captured by a laser scanner (LiDAR) representing the surfaces of an existing building or site, imported into Revit or a modeling platform as a reference for accurately modeling existing conditions — commonly used on renovation projects where as-built drawings are unreliable or unavailable.
Project Browser — Revit UI term
The panel in Revit's interface that provides a hierarchical, navigable list of every view, sheet, schedule, family, and group in the project model — the primary means of navigating a large Revit project file.

Q

Quantity Takeoff (QTO) — estimating term
The process of extracting material and component quantities (square footage of drywall, linear feet of duct, count of doors) directly from the BIM model's data, rather than measuring manually from 2D drawings, used to support cost estimating and procurement — one of the most commonly cited efficiency gains of BIM adoption over traditional CAD-based estimating.

R

Revit — software
Autodesk's parametric BIM authoring platform, the dominant tool used by architecture, structural, and MEP engineering firms in North America to create intelligent, data-rich 3D models from which drawings, schedules, and quantities are automatically generated.
RFI (Request for Information) — construction administration term
A formal question submitted by the contractor to the design team during construction when the drawings or model do not provide sufficient information to proceed, or when a field condition conflicts with the design — RFI responses are often incorporated back into the BIM model to keep the as-built record current.

S

Schedule — Revit documentation term
A tabular view in Revit that automatically lists model elements and their parameters (e.g., a door schedule listing every door's mark, size, type, and fire rating) — schedules update live as the model changes, eliminating the need to manually re-count and re-tabulate elements after a design revision.
Sheet — Revit documentation term
A drawing sheet in Revit onto which views (plans, sections, schedules, details) are placed for issuance as a printed or PDF construction document — analogous to a drawing "layout" in AutoCAD, but composed of live model views rather than independently drafted geometry.

T

Tag — Revit annotation term
A view-specific annotation that displays a parameter value (such as a room number, door mark, or equipment tag) associated with a model element, automatically updating if that parameter changes — distinguished from text, which is static and unlinked to model data.
Type Parameter — Revit term
A property of a Revit family type that applies uniformly to every instance of that type in the model — changing a type parameter (such as a window's glazing material) updates every placed window of that type simultaneously, as opposed to an instance parameter, which affects only one placed element.

V

View Template — Revit term
A saved collection of view settings (visibility/graphics overrides, scale, detail level, filters) that can be applied to multiple views to enforce consistent graphic standards across a large drawing set without manually configuring each view.
Visibility/Graphics Overrides (V/G) — Revit term
The per-view settings that control which model categories are shown or hidden, and how they are displayed (line weight, color, pattern) in a specific view — used to produce different graphic representations of the same underlying model for different drawing purposes (design development vs. construction documents).

W

Workset — Revit worksharing term
A named subset of model elements used in Revit's worksharing feature to divide a large project among multiple team members working simultaneously in a shared central model — each user can "check out" and edit elements on their assigned workset without conflicting with teammates editing a different workset, while still seeing the full coordinated model.
Worksharing — Revit collaboration feature
Revit's built-in mechanism for enabling multiple users to work simultaneously in the same project file via a central model hosted on a server or in the cloud (ACC), with each user's local file synchronizing changes back to the central model at regular intervals.

X

XREF (External Reference) — AutoCAD term
An AutoCAD drawing file linked into another drawing for reference, similar in concept to a linked model in Revit, allowing multiple drafters to coordinate around a shared base drawing (such as an architectural background) without copying and duplicating geometry.