How are IFC Units and IFC data types specified for properties?

[Moult]

How do I specify which IFC unit a property has? Right now the units are overly simplistic and depending on vendor interpretations even the simplest of IDS checks will fail (e.g. IfcLabel vs IfcIdentifier vs IfcText).

[atomczak]

Hi @Moult, the bSDD was built based on an ISO specification that wasn't aligned with the existing IFC.

Your request is very valid, and to solve this we plan to add an optional attribute to address this: 'IfcDataType'. By default, and for all existing properties, it will fill in the empty values according to this mapping:

• String → IfcText
• Double → IfcReal
• Integer → IfcInteger
• Boolean → IfcBoolean
• Date → IfcTime

Please let me know if that would satisfy your need, or if you have better suggestions.

[Moult]

Thats excellent! I would recommend defaulting to ifclabel, not ifctext, as in practice the former is significantly more applicable. I have never seen the lord of the rings in IFC yet :) Dion Moult Sent from [Proton Mail](https://proton.me/mail/home) for Android.

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On Tuesday, 12/16/25 at 03:48 ArturTomczak ***@***.***> wrote: atomczak left a comment [(buildingSMART/bSDD#138)](#138 (comment)) Hi ***@***.***(https://github.com/Moult), the bSDD was built based on an ISO specification that wasn't aligned with the existing IFC. Your request is very valid, and to solve this we plan to add an optional attribute to address this: 'IfcDataType'. By default, and for all existing properties, it will fill in the empty values according to this mapping: - String → IfcText - Double → IfcReal - Integer → IfcInteger - Boolean → IfcBoolean - Date → IfcTime Please let me know if that would satisfy your need, or if you have better suggestions. — Reply to this email directly, [view it on GitHub](#138 (comment)), or [unsubscribe](https://github.com/notifications/unsubscribe-auth/AAAVR3QYMGFFHZ2OB4XPU334B3Q7BAVCNFSM6AAAAACIKHXZQKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTMNJWGY2DKMJWGQ). You are receiving this because you were mentioned.Message ID: ***@***.***>

[atomczak]

I have never seen the lord of the rings in IFC yet :)

One to rule them all? 😄

I would recommend defaulting to ifclabel, not ifctext, as in practice the former is significantly more applicable.

IfcLabel might be more popular, but does it mean it is better? The IfcText is broader, as it doesn't have the 255 char limit. And if we merge the two in the next version of IFC, I would rather see IfcText there. However, bSDD users may choose IfcLabel if they wish.