Construction / Building-Information-Modelling DSLs Family Index


type: language-family-index family: construction-bim languages_catalogued: 27 tags: [language-reference, family-index, construction-bim, ifc, step-express, ifc-spf, ifcxml, ifcowl, cis2, gbxml, cobie, bcf, bsdd, mvdxml, ids, landxml, brick, haystack, dwg, dxf, energyplus, idf, openstudio, speckle, forge, cim-xml, iso-19650, openbim]

Construction / Building-Information-Modelling — Family Index

Family overview

Construction and building-information-modelling (BIM) DSLs are the textual schemas, ontologies, and exchange grammars used to describe buildings, civil infrastructure, MEP systems, and the built environment over its lifecycle. The defining standard for thirty years has been IFC (Industry Foundation Classes), buildingSMART’s openBIM schema, first published as IFC 1.0 in 1997 and steadily evolving through IFC 2x3 (2006), IFC 4 (2013), and IFC 4.3 — formalised as ISO 16739-1:2024 on 4 January 2024 (buildingSMART announcement). IFC 4.3 was the watershed expansion that brought horizontal infrastructure — rail, road, bridge, ports, waterways — under the same openBIM umbrella that had previously been vertical-buildings-only. The current documentation revision is IFC 4.3.2 (e.g. IFC4X3_ADD2, the 2026 elaborations clarify the ISO schema without changing it).

Underneath IFC sits STEP / ISO 10303 and its schema language EXPRESS — a 1990s-era data-modelling DSL from CAD/CAM/PLM interoperability work that defines the type system, attributes, inverse relationships, and WHERE-rule constraints IFC depends on. The dominant on-disk serialisation of an IFC model is IFC-SPF (STEP Physical File), the #42=IFCWALL(...) ASCII format inherited directly from STEP Part 21. XML (ifcXML) and RDF/OWL (ifcOWL) serialisations exist for linked-data and XML-toolchain use cases but are far less common in production.

A modern second-order language layer surrounds IFC: IDS (Information Delivery Specification) 1.0 became an official buildingSMART standard on 1 June 2024, superseding the older mvdXML approach as the way to express “what information must be in an IFC delivery for this exchange?” in a computer-checkable form (buildingSMART IDS); bSDD (buildingSMART Data Dictionary) provides the multilingual classification REST API; BCF (BIM Collaboration Format) and BCF API 3.0 carry issue-tracking and model-coordination communications between authoring tools; COBie (Construction Operations Building Information Exchange) is the spreadsheet-based facility-handover subset of IFC; and ISO 19650 (parts 1–6, 2018–2025, with major revisions of parts 1–3 in public consultation as of March 2026) is the process standard wrapping all of this — the how to manage information layer to IFC’s what is the information layer.

The proprietary-vendor zoo coexists alongside openBIM: Autodesk Revit (.rvt), Graphisoft ArchiCAD (.pln), and Robert McNeel Rhino (.3dm) plus Grasshopper visual-programming definitions dominate the authoring tool market. Autodesk also owns AutoCAD’s DWG and the text-based DXF exchange format, and the Forge / APS (Autodesk Platform Services) cloud layer. Energy analysis has its own DSL ecosystem — EnergyPlus IDF (Input Data File), the NREL OpenStudio wrapper around it (currently EnergyPlus 25.2.0 / OpenStudio 3.11.0 as of 2026), gbXML (Green Building XML, current 8.01) for the design-tool-to-energy-tool handoff, and Modelica building libraries for whole-building physics simulation. And on top of all of it, the smart-building / building-ontology layer — Brick Schema (currently 1.4.4, 2025-05-01, RDF/SPARQL-queryable) and Project Haystack (currently Haystack 4, tag-based) — addresses the “data analytics over running building telemetry” use case that IFC was never designed for. Finally, watch for the name collision: CIM XML (IEC 61970) is the electrical-grid Common Information Model, not generic BIM.

In our deep library

No standalone deep notes for any of these BIM-specific formats. Cross-references to adjacent Tier 3 family indexes:

  • geospatialCityGML, CDB, GIS overlap. CityGML sits at the BIM/GIS boundary (its LoD1-4 city models overlap with simplified IFC site-level geometry); CDB (OGC Common Database) is explicitly the bridge between BIM, geospatial, and simulation; and the IFC 4.3 infrastructure subspecs (Bridge/Tunnel/Road/Rail) bring openBIM into territory historically owned by geospatial.
  • industrial-automationBACnet object model, building-automation overlap. BACnet (ASHRAE 135) is the long-running building-automation protocol; its object model overlaps with Brick/Haystack telemetry semantics. KNX, Modbus, and OPC UA are adjacent.
  • api-descriptionXML Schema, BCF API REST. IFC, IFC-XML, gbXML, mvdXML, IDS, BCF, and CIM XML are all defined by XSD or RNG schemas; BCF API 3.0 is REST/JSON.
  • scientificModelica energy modelling. Modelica Buildings Library (LBNL) is the open-source Modelica package for whole-building simulation; overlaps with EnergyPlus and OpenStudio.
  • notation-specEXPRESS / ISO 10303-11 is a formal information-modelling notation; arguably as much a notation language as a schema language.
  • visual-dataflowGrasshopper, Dynamo, Speckle. Grasshopper (for Rhino) and Dynamo (for Revit) are the dominant AEC visual-programming environments; Speckle is the open-source 3D data platform that ties them together.

Tier 3 family table — IFC family + STEP underpinnings

FormatFirst appearedOriginTypeStatus (2026)URL
IFC (Industry Foundation Classes)1997 (IFC 1.0); IFC 4.3 = ISO 16739-1:2024 (approved 4 Jan 2024)buildingSMART International (originally IAI, 1995)openBIM data-model schema; written in EXPRESS, serialised as SPF/XML/OWL/JSONDe facto and de jure standard. Current schema IFC 4.3.2 (IFC4X3_ADD2, 2026 docs); covers vertical buildings + horizontal infrastructure (rail/road/bridge/ports)https://technical.buildingsmart.org/standards/ifc/
IFC-SPF (STEP Physical File / Part 21)1994 (ISO 10303-21)ISO/STEP committeeASCII text serialisation #42=IFCWALL(...); the dominant IFC on-disk formatActive, ubiquitous; the .ifc file you actually seehttps://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/
ifcXML / ifcXML42001 (ifcXML for IFC 2x); ifcXML4 for IFC 4buildingSMARTXML serialisation of the EXPRESS-defined schemaActive but minority; XML-toolchain consumers; XSD generated from the EXPRESS schemahttps://technical.buildingsmart.org/standards/ifc/ifc-formats/
ifcOWL~2014 (W3C LBD CG); referenced in IFC 4 docsW3C Linked Building Data CG + buildingSMARTOWL/RDF version of IFC for linked-data and SPARQL queryingActive but research-leaning; auto-generated from EXPRESS; less common in industryhttps://www.w3.org/community/lbd/
IFC-JSON2017+ (experimental); becoming first-class in IFC 5buildingSMARTJSON serialisation; lighter than SPF/XML for web toolingEmerging; IFC 5 (alpha 2025, project plan vote closed Aug 2025) makes JSON-based representation a primary serialisationhttps://github.com/buildingSMART/IFC5-development
STEP / ISO 103031994 (first parts published)ISO TC 184/SC 4Family of data-exchange standards for product-data interoperability; IFC is one application protocolFoundational, still actively maintained; AP242 (managed model-based 3D engineering) is the aerospace/defence flagshiphttps://www.iso.org/standard/63141.html
EXPRESS (ISO 10303-11)1994ISO TC 184/SC 4Formal data-modelling DSL; entity types, attributes, inverse rels, WHERE rules, derived attrsFoundational for IFC and other STEP application protocols; little new uptake outside STEP-derived workhttps://www.iso.org/standard/38047.html
CIS/2 (CIMSteel Integration Standards)1995 (CIS), CIS/2 ~2003University of Leeds + AISCSTEP-based exchange schema for steel structures (members, connections, materials, fabrication)Active in steel-fabrication corner; IFC steel-detailing modules increasingly overlaphttps://www.cis2.org/
IFC 5 (in development)2025 alpha; project plan vote closed 8 Aug 2025buildingSMART InternationalNext-generation IFC; modularised; JSON-first serialisation; OpenUSD-influenced composition modelAlpha, still evolving; the long-term successor to IFC 4.3https://ifc5.technical.buildingsmart.org/
IFC Bridge / Tunnel / Road / Rail (sub-specs)Folded into IFC 4.3 (2024)buildingSMART infrastructure roomsDomain extensions to the IFC entity hierarchy for civil infrastructureActive; part of the ISO 16739-1:2024 standardhttps://technical.buildingsmart.org/standards/ifc/ifc-schema-specifications/

Tier 3 family table — Energy / sustainability / facility ops

FormatFirst appearedOriginTypeStatus (2026)URL
gbXML (Green Building XML)2000Green Building XML Consortium (orig. GeoPraxis)XML schema for design-tool → energy-analysis-tool handoffActive, current 8.01; ~50 vendor implementations (Autodesk, Trimble, Graphisoft, Bentley)https://www.gbxml.org/
COBie (Construction Operations Building Information Exchange)2007 (Bill East, US Army Corps of Engineers)US Army Corps + NIBS; UK BSI; ISO via 19650-4Spreadsheet-format subset of IFC for facility-handover asset data (no geometry, just data)Active; BS 1192-4:2014 superseded by BS EN ISO 19650-4:2022; US NBIMS-US v3.6 2025https://www.nibs.org/projects/cobie
EnergyPlus IDF (Input Data File)2001 (EnergyPlus 1.0)DOE / LBNL / NRELText-based key-value DSL for whole-building energy simulation input (objects + fields)Active; EnergyPlus 25.2.0 (2026); epJSON co-format since v8.9https://energyplus.net/
OpenStudio SDK2008NRELC++/Ruby/Python SDK wrapping EnergyPlus IDF + Radiance + Modelica; OSM model formatActive; OpenStudio 3.11.0 (2026) bundles EnergyPlus 25.2.0https://openstudio.net/
Modelica Buildings Library2009LBNL (Wetter et al.)Open-source Modelica package for whole-building HVAC/envelope/control simulationActive; overlaps scientific (Modelica language)https://simulationresearch.lbl.gov/modelica/
ISO 19650 (parts 1–6)2018 (P1–2); P3 2020; P4 2022; P5 2020; P6 2025ISO TC 59/SC 13Process standard for information management using BIM (not a data DSL); supersedes UK PAS 1192 seriesActive; P1–3 revisions in public consultation 10 March 2026, expected publication 2027 — proposed merger of P2+P3 into single asset-lifecycle processhttps://www.iso.org/standard/68078.html

Tier 3 family table — Civil / infrastructure / land

FormatFirst appearedOriginTypeStatus (2026)URL
LandXML1999 (v1.0); current v1.2 (2008)LandXML.org consortiumXML schema for civil/survey/grading data (alignments, surfaces, parcels, pipe networks)Active but ageing; v2.0 working draft since 2014, never finalised; IFC 4.3 and InfraGML are eating its lunchhttp://www.landxml.org/
CityGML2008 (CityGML 1.0); current 3.0 (2021)OGC + Karlsruhe / TU MunichXML/GML schema for 3D city models at LoD0-4Active; cross-listed in geospatial; sits at the BIM/GIS boundaryhttps://www.ogc.org/standard/citygml/
CDB (Common Database, OGC)2008 (CDB 1.0, originally Presagis); OGC standard since 2014; CDB 2.0 (2024)OGCSynthetic-environment storage standard; bridges BIM + geospatial + flight/driving-simActive; the BIM-↔-simulation glue layer; OGC CDB SWGhttps://www.ogc.org/standard/cdb/
CIM XML (IEC 61970)1999 (IEC 61970-1)IEC TC 57 / EPRICommon Information Model for electric power grids; XML + RDF profilesActive; distinct from generic BIM — this is the electrical-grid CIM, not architectural; ENTSO-E, CIMug, NERC use ithttps://webstore.iec.ch/publication/6208
ADMS / IEC 61968 (Asset Data Management for utilities)2003 (IEC 61968-1)IEC TC 57Companion to CIM for utility asset management & operations (DMS/OMS/AMS)Active; CIM/CIM-XML reused as the underlying schemahttps://webstore.iec.ch/publication/63125

Tier 3 family table — Building ontologies / queries / requirements

FormatFirst appearedOriginTypeStatus (2026)URL
IDS (Information Delivery Specification) 1.02021 first drafts; 1.0 official 1 June 2024buildingSMART InternationalXML-based DSL for specifying BIM information requirements; supersedes mvdXMLActive, current 1.0; 1.1 and 2.0 feedback being collected; the modern BIM-data-requirements standardhttps://www.buildingsmart.org/standards/bsi-standards/information-delivery-specification-ids/
mvdXML (Model View Definition)2012buildingSMARTXML DSL for subsetting IFC schemas to MVDs (specific exchange views)Superseded by IDS for new work; still used in legacy MVD certificationshttps://technical.buildingsmart.org/standards/mvd/mvd-xml/
bSDD (buildingSMART Data Dictionary)2010s; relaunched as REST API 2020+buildingSMART InternationalMultilingual classification system + REST API for property/classification mappingActive; the IFC-property-lookup backbone; integrates with IDShttps://www.buildingsmart.org/users/services/buildingsmart-data-dictionary/
BCF (BIM Collaboration Format) — file2009 (BCF 1.0)buildingSMART (proposed by Tekla + Solibri)ZIP-of-XML format for model-issue communication (markup, viewpoint, comments)Active; BCF 3.0 (current); supplemental Documents folder added in 3.0https://technical.buildingsmart.org/standards/bcf/
BCF API 3.02014 (1.0); current 3.0 (2022)buildingSMARTREST/JSON API spec for BCF servers (BIMcollab, Newforma Konekt, Catenda, Bricks, usBIM, OpenProject, …)Active, the REST companion to BCF-filehttps://github.com/buildingSMART/BCF-API
Brick Schema2016 (UC Berkeley + UCSD + IBM Research)Brick Consortium (now hosted by LF Energy)RDF/OWL ontology for buildings; SPARQL-queryable; HVAC/lighting/security/fireActive; current 1.4.4 (2025-05-01); merged with RealEstateCore ontology in 1.4.0https://brickschema.org/
Project Haystack2011Project Haystack community (orig. SkyFoundry / J2 Innovations / Tridium)Tag-based ontology for smart-building telemetry data; flat list of tags → Haystack 4 type/subtype model + Trio/Zinc serialisationsActive; Haystack 4 current; widely supported by BAS vendors (Tridium Niagara 4.14+)https://project-haystack.org/
mvdXML 1.12016 (revised)buildingSMARTXML schema for MVD concept-templates and applicability rulesLegacy; new work goes to IDShttps://technical.buildingsmart.org/standards/mvd/

Tier 3 family table — Vendor / authoring / cloud formats

FormatFirst appearedOriginTypeStatus (2026)URL
AutoCAD DWG1982Autodesk (Mike Riddle / John Walker)Binary CAD drawing format; reverse-engineered by ODA (Open Design Alliance)Dominant 2D CAD format; proprietary but ODA Teigha provides interophttps://www.autodesk.com/products/autocad/overview
AutoCAD DXF (Drawing Exchange Format)1982AutodeskASCII (and binary) text format for CAD drawing exchange; group-code / value pairsActive, the open text counterpart to DWG; ubiquitous interchange formathttps://help.autodesk.com/view/OARX/2026/ENU/?guid=GUID-235B22E0-A567-4CF6-92D3-38A2306D73F3
Revit (.rvt / .rfa / .rte)2002 (Revit 4.0 acquired by Autodesk from Revit Technology Corp)AutodeskProprietary BIM authoring file format; reads/writes via Revit API + ForgeDominant vertical-buildings authoring tool worldwide; IFC export quality the main openBIM leverhttps://www.autodesk.com/products/revit/overview
ArchiCAD (.pln)1984 (ArchiCAD 1.0)Graphisoft (Hungary, now part of Nemetschek)Proprietary BIM authoring file formatActive; second-largest BIM authoring tool; strong IFC supporthttps://graphisoft.com/solutions/archicad
Rhino 3DM~1998 (Rhino 1.0)Robert McNeel & AssociatesOpen NURBS-based 3D modelling file format (openNURBS toolkit)Active; widely used in computational-design AEC; the open-source openNURBS lib enables cross-tool readshttps://www.rhino3d.com/
Grasshopper definitions (.gh / .ghx)2007 (Rhino plugin, David Rutten)Robert McNeel & AssociatesVisual dataflow programming environment for Rhino; .gh binary / .ghx XMLActive; the AEC industry’s dominant visual-programming environment; cross-listed visual-dataflowhttps://www.grasshopper3d.com/
Dynamo (Revit)2014Autodesk (Ian Keough)Visual dataflow for Revit / Civil 3D / FormIt; .dyn (JSON)Active; the Revit-native counterpart to Grasshopperhttps://dynamobim.org/
Speckle2018 (founded); $12.5M Series A 2024Speckle Systems (Dimitrie Stefanescu)Open-source 3D data platform; .speckle / JSON-based object model; commits, branches, versioningActive, fast-growing; integrates Rhino/Revit/Grasshopper/IFC; “Speckle Intelligence” launched 2025https://speckle.systems/
Forge / APS (Autodesk Platform Services)2015 (Forge), rebranded APS in 2023AutodeskCloud BIM API platform (Model Derivative, Data Management, Viewer, ACC); JSON+RESTActive, Autodesk’s strategic cloud layerhttps://aps.autodesk.com/
BIMserver (open-source IFC database)2009TNO / TU EindhovenOpen-source IFC server with revisioning, queries, pluginsActive but lower velocity; adjacent to Speckle’s spacehttps://github.com/opensourceBIM/BIMserver

Notable threads

  • IFC 4.3 = ISO 16739-1:2024 is the openBIM watershed for civil infrastructure. Until 2024, IFC was a “vertical buildings” schema (walls, slabs, beams, MEP). IFC 4.3 folded in Bridge / Tunnel / Road / Rail / Ports / Waterways as first-class domain extensions, made it an official ISO standard (ISO 16739-1:2024, approved 4 Jan 2024 — see buildingSMART announcement), and gave national infrastructure procurement bodies (Highways England, Norwegian Roads, Deutsche Bahn, the FRA) a single open exchange standard to mandate. This is why the openBIM mandate wave (UK 2016, Germany Stufenplan, Norway, Denmark, France, Spain, US GSA) accelerated post-2024: IFC 4.3 closed the infrastructure gap that previously forced rail/road agencies to write their own bespoke schemas or accept Bentley/Autodesk lock-in.

  • IDS 1.0 supersedes mvdXML for “what information is required?” mvdXML (Model View Definition) was the 2012-vintage answer for declaring “an IFC export for steel coordination must contain at least these entities + these property sets.” It was technically capable but unfriendly — verbose XML, weak tooling, hard to author by hand. IDS (Information Delivery Specification) 1.0 became official on 1 June 2024 and is a clean restart: simpler XML, much better tool support (Solibri, BIMcollab, ACCA usBIM, Bonsai, IfcOpenShell), human-authorable, and aligned with the IFC property + classification system through bSDD. IDS is rapidly becoming the standard way to express BIM requirements in employer’s information requirements (EIRs) under ISO 19650.

  • Brick + Haystack are the smart-building ontology layer that IFC is not. IFC is designed for the design and construction lifecycle — it captures geometry, classifications, properties, schedules. It is poor at “this thermostat in room 312 streams a sensor reading every 60 seconds.” That space is owned by Brick Schema (RDF/SPARQL, current 1.4.4, merged with RealEstateCore in 1.4.0, Brick Consortium) and Project Haystack (tag-based, Haystack 4). Brick is academic / research-led; Haystack is BAS-vendor-led (Tridium Niagara, J2 Innovations, SkyFoundry). Increasing work is being done to bridge IFC → Brick (e.g. the LBL “BrickIFC” tooling and IFC4Brick mapping research), recognising that the design-time and operations-time models need to converge.

  • gbXML vs IFC vs OpenStudio IDF for energy analysis is a three-way standoff. Energy modellers want geometry + thermal-zone topology + construction layers + internal loads + HVAC system definitions. IFC has all of this in principle but energy-tool vendors find it bloated and inconsistently authored. gbXML 8.01 is a leaner XML schema that ~50 tools (Revit, ArchiCAD, IES VE, OpenStudio, DesignBuilder) export to. EnergyPlus IDF is the actual simulation input — text key-value DSL — and OpenStudio’s OSM model wraps it. The 2026 reality is: design tools export gbXML, modellers fix it up in OpenStudio, OpenStudio writes IDF, EnergyPlus simulates. IFC-to-IDF round-tripping remains technically possible but operationally rare.

  • The Revit lock-in vs. openBIM dynamic continues to shape industry economics. Autodesk Revit’s .rvt is a proprietary binary; the only way to fully interoperate with Revit projects is via the Revit API (Forge/APS) or via IFC export — which historically has been lossy. Government openBIM mandates (UK BIM Mandate 2016, US GSA, EU member states catalogued in buildingSMART Global Mandates 2025) explicitly require deliverables in IFC, not RVT, precisely to break this lock-in. Speckle, ODA’s Teigha, and the open IFC tools (IfcOpenShell, xBIM, Bonsai/BlenderBIM) form the technical counterweight.

  • ISO 19650 is the process standard, IFC is the data standard; 2026 revisions are merging delivery and operations. ISO 19650 parts 1–6 (published 2018–2025) define the project information-management process under BIM — common data environments, information delivery plans, security, H&S, asset-operation handoff. In March 2026 parts 1–3 went out for public consultation, with proposed structural changes including dropping the formal distinction between the delivery phase (P2) and operational phase (P3) in favour of a single continuous asset-lifecycle process, and a vocabulary shift from “BIM” toward broader “Information Management.” Expected publication 2027.

  • CIM XML (IEC 61970) is the electrical-grid Common Information Model — easily confused with generic BIM, fundamentally different. When someone says “CIM” in an architecture/AEC context, they usually mean City Information Modelling or generic Common Information Modelling. When an electrical utility says “CIM,” they mean IEC 61970 CIM, the schema covering generation, transmission, substations, breakers, busbars, RDF-profiled, used by ENTSO-E, EPRI, NERC, and most North-American/European TSOs. The two communities barely talk. Anyone working at the building↔grid boundary (DERs, microgrids, EV charging) ends up needing both ontologies.

  • IFC 5 (in alpha 2025–2026) modularises and JSON-ifies the schema. The IFC 4 monolith is universally acknowledged as too large, too coupled, and too STEP-EXPRESS-bound. IFC 5 (Core Project Plan vote closed 8 Aug 2025, alpha development active at github.com/buildingSMART/IFC5-development) reorganises around a modular core + domain extensions, adopts a JSON-native serialisation as a first-class citizen, and takes design cues from Pixar’s OpenUSD composition model. It is not expected to be production-ready before 2027–2028; IFC 4.3 will remain the practical standard for years.

Citations