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Project data & BIM
About BIM-based management of attributes, schedules, templates, favorites, hotlinks, projects in general, quality assurance, etc.

Expression property custom value danger


To GS with love,




AC 25 SWE Full

HP Zbook Fury 15,6 G8. 32 GB RAM. Nvidia RTX A3000.

Rajesh Patil

Hi, I think "Expressions" are based on one way traffic. Data collected from source elements will be considered for further processing. Any end result from the expression cannot be send back to the source elements. Once you type the new value for expression based defined property then its get converted to "custom value" and the "expression" gets override. Setting back to "Default" will collect the information from the source.

Element ID.png

Rajesh Patil
AC 09-26 | INT | WIN11 64
Dell Inspiron 7591, Core i9, 9880H 2.30GHz, 16.0GB, NVidia GeForce GTX1650, 4.0GB, SSD Internal 500GB, Dell SSD External 250GB


Good point @Rajesh Patil but I agree with @Mats_Knutsson the reported data from an "expression" Property should be locked / unmediatable in the schedule / label. The only way to edit the reported data from an "expression" must be to actually edit the formula in the expression in the Properties Manager only (similar to an Option Set property).

Francois Swanepoel

Hiking, Motorbiking, Good food, Gr8! Beer & excellent conversation 😉 - Architecture - BIM Implementation - ArchiCAD Training - LiDAR Digital Survey - Scan2BIM As-Built - Property Compliance - Virtual Reality & Render Studio


It can NOT be as it is now. We use schedules for everything...quality control and adjustments alike. One of the key features with a BIM-tool is one single source of information (well data). I need to contact GS directly to check possibility for a hotfix to lock expression property values.

AC 25 SWE Full

HP Zbook Fury 15,6 G8. 32 GB RAM. Nvidia RTX A3000.

Matthew Johnson

If we can't get a way to lock the custom overiding of expression values, the next best thing would be to have an ability to have graphic overides in schedules to highlight were values have been custom edited rather than by their default expression.

Matthew Johnson - P O W E . Architects
AC25, Windows 11 64bit
Dell Precision 5520 i7 w/ Nvidia Quadro M1200 4K dual
i9-12900K w/ Nvidia RTX 3080 4K
I'd rather be sailing.

Andreas _kerlund



I totally agree with Mats. We have had so many cases where users have unwittingly have changed expression values in a schedule. The broken chain symbol in the objects properties settings tells you what have happened, but only if you know what you are looking for.

It needs fixing.

Andreas Åkerlund, Arkitekt SAR
Arkitekthuset Jönköping AB
ArchiCAD 5 to 25
Windows 10 64 bit
Intel i9 7920x @ 2.9 GHz, 64 GB RAM

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