# Developers **URL:** https://forums.buildingsmart.org/c/developers/28.md [Latest](https://forums.buildingsmart.org/latest.md) · [Categories](https://forums.buildingsmart.org/categories.md) · [Tags](https://forums.buildingsmart.org/tags.md) --- ## [About the Developers category](https://forums.buildingsmart.org/t/about-the-developers-category/48)
**Author:** [@jwouellette](https://forums.buildingsmart.org/u/jwouellette)\ **Replies:** 0
Discussions and information for software developers regarding implementation of buildingSMART standards Please note that the IFC Schema Specifications - buildingSMART Technical and GitHub have more information. --- ## [Open Data Optimization: Real-Time Urban Spatial Layouts (MPT Math) Syncing to BIM Models](https://forums.buildingsmart.org/t/open-data-optimization-real-time-urban-spatial-layouts-mpt-math-syncing-to-bim-models/6564)
**Author:** [@sherifmagd](https://forums.buildingsmart.org/u/sherifmagd)\ **Replies:** 0\ **Last updated:** [August 29, 2026, 11:36am UTC](https://forums.buildingsmart.org/t/open-data-optimization-real-time-urban-spatial-layouts-mpt-math-syncing-to-bim-models/6564 "2026-08-29T11:36:30Z")
Hello buildingSMART Community, I wanted to share an open-source workflow research project I recently completed for a Devpost hackathon called “BIM MPT Urban Optimize.” The project explores how we can leverage external o… --- ## [Validation Service Updates](https://forums.buildingsmart.org/t/validation-service-updates/4992)
**Author:** [@Evandro](https://forums.buildingsmart.org/u/Evandro)\ **Replies:** 35\ **Last updated:** [August 7, 2026, 1:11am UTC](https://forums.buildingsmart.org/t/validation-service-updates/4992 "2026-08-07T01:11:03Z")
Hi :wave: In this thread, we will inform you of planned and recently released features of the bSI Validation Service. We will cover new platform features as well as new rules implemented. :heavy\_check\_mark: We will be … --- ## [bSDD tech updates](https://forums.buildingsmart.org/t/bsdd-tech-updates/4889)
**Author:** [@artur\_tomczak](https://forums.buildingsmart.org/u/artur_tomczak)\ **Replies:** 35\ **Last updated:** [July 30, 2026, 8:25am UTC](https://forums.buildingsmart.org/t/bsdd-tech-updates/4889 "2026-07-30T08:25:34Z")
Hi :wave: In this thread, we will inform you of planned and recently implemented bSDD updates that might affect you. We will cover changes to the API, search page, management portal, data model, documentation, and techn… --- ## [IfcSpatialZone and IfcExternalSpatialElement confusion about low to high levels in spatial tree](https://forums.buildingsmart.org/t/ifcspatialzone-and-ifcexternalspatialelement-confusion-about-low-to-high-levels-in-spatial-tree/3495)
**Author:** [@Moult](https://forums.buildingsmart.org/u/Moult)\ **Replies:** 6\ **Last updated:** [May 27, 2026, 9:51am UTC](https://forums.buildingsmart.org/t/ifcspatialzone-and-ifcexternalspatialelement-confusion-about-low-to-high-levels-in-spatial-tree/3495 "2026-05-27T09:51:26Z")
The documentation states: 4.4.1.4 Spatial Composition The order of spatial structure elements being included in the concept for builing projects are from high to low level: IfcProject, IfcSite, IfcBuilding, IfcBuildin… --- ## [WBS Representation](https://forums.buildingsmart.org/t/wbs-representation/6495)
**Author:** [@RenzoVenuti](https://forums.buildingsmart.org/u/RenzoVenuti)\ **Replies:** 3\ **Last updated:** [May 11, 2026, 10:08am UTC](https://forums.buildingsmart.org/t/wbs-representation/6495 "2026-05-11T10:08:17Z")
What is the correct and standard way (IfcProduct, Property set, IfcLinearPlacement,ecc..) to represent a WBS in relation to an IfcAlignment? --- ## [Alignment Based Reference View](https://forums.buildingsmart.org/t/alignment-based-reference-view/6414)
**Author:** [@RenzoVenuti](https://forums.buildingsmart.org/u/RenzoVenuti)\ **Replies:** 5\ **Last updated:** [February 23, 2026, 7:42am UTC](https://forums.buildingsmart.org/t/alignment-based-reference-view/6414 "2026-02-23T07:42:48Z")
Has the Alignment Based Reference View been published, and if so, where? --- ## [About interchange in a road](https://forums.buildingsmart.org/t/about-interchange-in-a-road/6369)
**Author:** [@zfgis](https://forums.buildingsmart.org/u/zfgis)\ **Replies:** 0\ **Last updated:** [December 24, 2025, 12:56am UTC](https://forums.buildingsmart.org/t/about-interchange-in-a-road/6369 "2025-12-24T00:56:17Z")
Hello,everyone. In IFC verson 4.3,how do we express many interchanges in the road? A interchange may include many ramps. A ramp may include many bridges and many roadsegments. Thank you! --- ## [Nesting IfcMaterialLayers, IfcMaterialConstituents ((ABS)IfcMaterialDefinition instead of IfcMaterial)](https://forums.buildingsmart.org/t/nesting-ifcmateriallayers-ifcmaterialconstituents-abs-ifcmaterialdefinition-instead-of-ifcmaterial/6345)
**Author:** [@jakob-beetz](https://forums.buildingsmart.org/u/jakob-beetz)\ **Replies:** 0\ **Last updated:** [November 28, 2025, 11:16am UTC](https://forums.buildingsmart.org/t/nesting-ifcmateriallayers-ifcmaterialconstituents-abs-ifcmaterialdefinition-instead-of-ifcmaterial/6345 "2025-11-28T11:16:13Z")
Hi all, I wonder what the reasoning behind the “limitation” of IfcMaterialLayer and IfcMaterialConstituent on the Material attributes are to be of type IfcMaterial instead of allowing abstract IfcMaterialDefinition . U… --- ## [IFC 5 Encoding](https://forums.buildingsmart.org/t/ifc-5-encoding/6276)
**Author:** [@RenzoVenuti](https://forums.buildingsmart.org/u/RenzoVenuti)\ **Replies:** 1\ **Last updated:** [September 9, 2025, 9:55am UTC](https://forums.buildingsmart.org/t/ifc-5-encoding/6276 "2025-09-09T09:55:47Z")
For ifc 5 the standard encoding will be UTF-8? --- ## [bSDD API list class properties](https://forums.buildingsmart.org/t/bsdd-api-list-class-properties/6114)
**Author:** [@artur\_tomczak](https://forums.buildingsmart.org/u/artur_tomczak)\ **Replies:** 3\ **Last updated:** [June 26, 2025, 7:54am UTC](https://forums.buildingsmart.org/t/bsdd-api-list-class-properties/6114 "2025-06-26T07:54:05Z")
Question from a user: I am trying to access and read a specific Property Set from bSDD. However, I am encountering some difficulties. I am specifically interested in the following Property Set: Code: EC004822 Identi… --- ## [IfcFaceBasedSurfaceModel documentation](https://forums.buildingsmart.org/t/ifcfacebasedsurfacemodel-documentation/6137)
**Author:** [@SJL](https://forums.buildingsmart.org/u/SJL)\ **Replies:** 1\ **Last updated:** [June 2, 2025, 7:11am UTC](https://forums.buildingsmart.org/t/ifcfacebasedsurfacemodel-documentation/6137 "2025-06-02T07:11:39Z")
In documentation it says “IFC4-CHANGE The entity has been deprecated and shall not be used. The entity IfcFacetedBrep shall be used instead.” However FacetedBrep is a solid model. IfcFaceBasedSurfaceModel is not (necess… --- ## [Official Model View Definitions for IFC 4.3](https://forums.buildingsmart.org/t/official-model-view-definitions-for-ifc-4-3/5737)
**Author:** [@schilu](https://forums.buildingsmart.org/u/schilu)\ **Replies:** 6\ **Last updated:** [June 2, 2025, 6:01am UTC](https://forums.buildingsmart.org/t/official-model-view-definitions-for-ifc-4-3/5737 "2025-06-02T06:01:17Z")
Hi, Where can I find the definitions of the official Model View Definitions (Reference View, Alignment Based Reference View, Design Transfer View) for IFC 4.3? There is no direct link in the IFC documentation. Also, th… --- ## [Verification Needed: Connecting Sensors/Controllers](https://forums.buildingsmart.org/t/verification-needed-connecting-sensors-controllers/6126)
**Author:** [@shihangzhang](https://forums.buildingsmart.org/u/shihangzhang)\ **Replies:** 0\ **Last updated:** [May 19, 2025, 7:01am UTC](https://forums.buildingsmart.org/t/verification-needed-connecting-sensors-controllers/6126 "2025-05-19T07:01:24Z")
I’m implementing control system components in IFC and need verification on my connection approach. According to the buildingSMART documentation, the recommended way is to connect outputs to inputs through Port Nesting pr… --- ## [IFC 5 and API](https://forums.buildingsmart.org/t/ifc-5-and-api/6102)
**Author:** [@RenzoVenuti](https://forums.buildingsmart.org/u/RenzoVenuti)\ **Replies:** 1\ **Last updated:** [May 13, 2025, 10:33am UTC](https://forums.buildingsmart.org/t/ifc-5-and-api/6102 "2025-05-13T10:33:32Z")
Is it buildingsmart’s intention to make available an API to read and write the new IFC 5 format? --- ## [Qset for basic quantities: Qset\_QuantityTakeOff ?](https://forums.buildingsmart.org/t/qset-for-basic-quantities-qset-quantitytakeoff/6019)
**Author:** [@ejs](https://forums.buildingsmart.org/u/ejs)\ **Replies:** 1\ **Last updated:** [April 27, 2025, 8:27am UTC](https://forums.buildingsmart.org/t/qset-for-basic-quantities-qset-quantitytakeoff/6019 "2025-04-27T08:27:01Z")
Hi All, I need to aggregate basic quantities for an element into some defined structure. Theres was a promising ‘Pset\_QuantityTakeOff’ in the IFC2x3, but it vanished away. For ‘basic quantities’ I mean Height, Length, … --- ## [Clarifying the Role of IFC STEP (SPF) in IFC5 and Its Relationship with Modern Formats like JSON](https://forums.buildingsmart.org/t/clarifying-the-role-of-ifc-step-spf-in-ifc5-and-its-relationship-with-modern-formats-like-json/6046)
**Author:** [@shihangzhang](https://forums.buildingsmart.org/u/shihangzhang)\ **Replies:** 1\ **Last updated:** [April 2, 2025, 12:16pm UTC](https://forums.buildingsmart.org/t/clarifying-the-role-of-ifc-step-spf-in-ifc5-and-its-relationship-with-modern-formats-like-json/6046 "2025-04-02T12:16:16Z")
Continued Relevance of STEP (SPF): Will STEP (SPF) remain the primary format for IFC5 compliance, particularly for regulatory submissions or archival purposes? Are there scenarios where STEP is mandatory versus option… --- ## [IFC for Tunnel](https://forums.buildingsmart.org/t/ifc-for-tunnel/6031)
**Author:** [@RenzoVenuti](https://forums.buildingsmart.org/u/RenzoVenuti)\ **Replies:** 1\ **Last updated:** [March 24, 2025, 8:26am UTC](https://forums.buildingsmart.org/t/ifc-for-tunnel/6031 "2025-03-24T08:26:47Z")
Will ifcTunnel be in ifc version 4.4? --- ## [How to validate IDS files?](https://forums.buildingsmart.org/t/how-to-validate-ids-files/5993)
**Author:** [@AntonioCWD](https://forums.buildingsmart.org/u/AntonioCWD)\ **Replies:** 6\ **Last updated:** [March 13, 2025, 4:44pm UTC](https://forums.buildingsmart.org/t/how-to-validate-ids-files/5993 "2025-03-13T16:44:43Z")
In order to properly use IDS files to validate IFC files, we should make sure, that IDS files are properly formatted. Just yesterday I heard from someone using IDS since its beginning, that different vendors produce IDS… --- ## [IfcSpatialZone and Graphisoft's IFC4 Architectural Reference Exchange EXPORT certification](https://forums.buildingsmart.org/t/ifcspatialzone-and-graphisofts-ifc4-architectural-reference-exchange-export-certification/3103)
**Author:** [@daviddelven](https://forums.buildingsmart.org/u/daviddelven)\ **Replies:** 5\ **Last updated:** [February 25, 2025, 3:10pm UTC](https://forums.buildingsmart.org/t/ifcspatialzone-and-graphisofts-ifc4-architectural-reference-exchange-export-certification/3103 "2025-02-25T15:10:26Z")
Hello everybody. On one hand, since Graphisoft Archicad already finally got (in 2019) the IFC4 Architectural Reference Exchange EXPORT buildingSMART certification, and on the other hand, IFC4 Schema already introduced t… --- ## [IFC4.3.2.0 Chapter 4 documentation error? - 4.1.2.4 Documentation Association](https://forums.buildingsmart.org/t/ifc4-3-2-0-chapter-4-documentation-error-4-1-2-4-documentation-association/5955)
**Author:** [@jwouellette](https://forums.buildingsmart.org/u/jwouellette)\ **Replies:** 0\ **Last updated:** [February 20, 2025, 3:54pm UTC](https://forums.buildingsmart.org/t/ifc4-3-2-0-chapter-4-documentation-error-4-1-2-4-documentation-association/5955 "2025-02-20T15:54:22Z")
Currently, “4 Fundamental concepts and assumptions” does NOT indicate that “4.1.2.4 Document Association” is within scope of either base MVD, BUT the individual entries for IfcDocumentReference and IfcDocumentInformation… --- ## [Contradictory rules for Pset prefix usage](https://forums.buildingsmart.org/t/contradictory-rules-for-pset-prefix-usage/5949)
**Author:** [@AntonioCWD](https://forums.buildingsmart.org/u/AntonioCWD)\ **Replies:** 3\ **Last updated:** [February 20, 2025, 2:23pm UTC](https://forums.buildingsmart.org/t/contradictory-rules-for-pset-prefix-usage/5949 "2025-02-20T14:23:21Z")
According to the buildingSMART documentation on IfcPropertySet for IFC 2x3 In addition any user defined property set can be captured, those property sets shall have a Name value not including the “Pset\_” prefix. The … --- ## [Contradictory rules for Name field (Entity Rule - IfcBuildingElementProxy.WR1)](https://forums.buildingsmart.org/t/contradictory-rules-for-name-field-entity-rule-ifcbuildingelementproxy-wr1/5951)
**Author:** [@AntonioCWD](https://forums.buildingsmart.org/u/AntonioCWD)\ **Replies:** 2\ **Last updated:** [February 20, 2025, 2:02pm UTC](https://forums.buildingsmart.org/t/contradictory-rules-for-name-field-entity-rule-ifcbuildingelementproxy-wr1/5951 "2025-02-20T14:02:11Z")
According to the validator the following line is violating a rule, where the name field has to exist(/be populated): #325286= IFCBUILDINGELEMENTPROXY(‘1kZKrDa5XBteRTcTyfP8Jx’,#11,$,$,‘F A L S C H’,#133475,$,‘F A L S C H… --- ## [Technical feedback on IFC5 development - Modularization and structural improvements](https://forums.buildingsmart.org/t/technical-feedback-on-ifc5-development-modularization-and-structural-improvements/5788)
**Author:** [@daviddelven](https://forums.buildingsmart.org/u/daviddelven)\ **Replies:** 6\ **Last updated:** [January 6, 2025, 12:31pm UTC](https://forums.buildingsmart.org/t/technical-feedback-on-ifc5-development-modularization-and-structural-improvements/5788 "2025-01-06T12:31:11Z")
As buildingSMART Spain, we recently published an analysis about IFC5’s development path (available at: The Evolution of IFC: The path to IFC5 - buildingSMART Spain). Following this publication, we received valuable techn… --- ## [IFC Delta/Partial Updates](https://forums.buildingsmart.org/t/ifc-delta-partial-updates/4427)
**Author:** [@gschleusner](https://forums.buildingsmart.org/u/gschleusner)\ **Replies:** 3\ **Last updated:** [January 2, 2025, 12:43pm UTC](https://forums.buildingsmart.org/t/ifc-delta-partial-updates/4427 "2025-01-02T12:43:54Z")
Hi All, At the last General Assembly Meeting it was agree that we look at Partial File Exchange to support sending updates vs full files. At least major vendors have the infrastructure to support this directly on Exp… --- ## [IfcAsset and IfcInventory SW implementation](https://forums.buildingsmart.org/t/ifcasset-and-ifcinventory-sw-implementation/3440)
**Author:** [@daviddelven](https://forums.buildingsmart.org/u/daviddelven)\ **Replies:** 5\ **Last updated:** [December 2, 2024, 9:52pm UTC](https://forums.buildingsmart.org/t/ifcasset-and-ifcinventory-sw-implementation/3440 "2024-12-02T21:52:26Z")
Hello to everybody, Does someone know about some SW implementation enabling the mapping or creation of the following IfcGroup subtypes: IfcAsset IfcInventory Thanks in advance David --- ## [What is the default for a derived unit that isn't set in the file?](https://forums.buildingsmart.org/t/what-is-the-default-for-a-derived-unit-that-isnt-set-in-the-file/5759)
**Author:** [@angel.velez](https://forums.buildingsmart.org/u/angel.velez)\ **Replies:** 6\ **Last updated:** [November 20, 2024, 1:28pm UTC](https://forums.buildingsmart.org/t/what-is-the-default-for-a-derived-unit-that-isnt-set-in-the-file/5759 "2024-11-20T13:28:44Z")
We are doing some work on importing parameters and found an interesting case. We have an old (not Revit) file that has a VOLUMETRICFLOWRATE property, but no corresponding derived unit. The unit assignments in the file … --- ## [Certification aspect geolocation](https://forums.buildingsmart.org/t/certification-aspect-geolocation/5750)
**Author:** [@Hans\_Lammerts](https://forums.buildingsmart.org/u/Hans_Lammerts)\ **Replies:** 0\ **Last updated:** [November 8, 2024, 9:05pm UTC](https://forums.buildingsmart.org/t/certification-aspect-geolocation/5750 "2024-11-08T21:05:56Z")
I was wondering. To what extend is handling geolocation part of the certification process of ifc certified software? (assuming geo-referencing is correctly applied) --- ## [Using IDS to Validate Property Attributes](https://forums.buildingsmart.org/t/using-ids-to-validate-property-attributes/5736)
**Author:** [@shihangzhang](https://forums.buildingsmart.org/u/shihangzhang)\ **Replies:** 1\ **Last updated:** [November 4, 2024, 9:38am UTC](https://forums.buildingsmart.org/t/using-ids-to-validate-property-attributes/5736 "2024-11-04T09:38:06Z")
Hello everyone, I’m wondering if it’s possible to validate property attributes using IDS. For example, I’d like to check the attribute “People” within the Pset\_SpaceThermalLoad of an IfcBuilding, which is expressed usi… --- ## [Is certification a "snapshot in time" or is it renewed?](https://forums.buildingsmart.org/t/is-certification-a-snapshot-in-time-or-is-it-renewed/4862)
**Author:** [@stefkeB](https://forums.buildingsmart.org/u/stefkeB)\ **Replies:** 8\ **Last updated:** [October 28, 2024, 7:40am UTC](https://forums.buildingsmart.org/t/is-certification-a-snapshot-in-time-or-is-it-renewed/4862 "2024-10-28T07:40:19Z")
Looking at the Software Certification page, we can read that e.g. Revit received certification for IFC2x3 in 2013. Here is the report for IFC 2x3 CV2.0 export, which was assigned to Revit 2013 https://ifc2x3.b-cert.o… [Next page](https://forums.buildingsmart.org/c/developers/28.md?page=1)