# Failed to specify the OmniClass parameter value of the family file

**URL:** <https://forum.dynamobim.com/t/failed-to-specify-the-omniclass-parameter-value-of-the-family-file/99816>\
**Category:** Revit\
**Tags:** revit, dynamo\
**Created:** [April 8, 2024, 7:26am UTC](https://forum.dynamobim.com/t/failed-to-specify-the-omniclass-parameter-value-of-the-family-file/99816 "2024-04-08T07:26:13Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![b10705001F2HWP](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/b10705001f2hwp/32/175165_2.png) [@b10705001F2HWP](https://forum.dynamobim.com/u/b10705001F2HWP)\
**Post date:** [April 8, 2024, 7:26am UTC](https://forum.dynamobim.com/t/failed-to-specify-the-omniclass-parameter-value-of-the-family-file/99816/1 "2024-04-08T07:26:13Z")

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Hello, I would like to ask why the OmniClass parameter value in the family file cannot be changed? (Because I failed to use dyamo to change the OmniClass value of the component, I want to change it directly in Revit.)  
Or I can only select the number provided by Revit and cannot enter it manually?

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/f/2/f214462bfc5fe040e0f52733016572e750373971.png)

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/2/a/2a07df9f454f52d79442abe8cc8e6df94ae27fa9.png)  
 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/e/2/e2beabcdd98774aea8f342b40841cc5561af2e7c.png)

But the value I want to specify is not in the OmniClass list provided by Revit. The OmniClass manual I refer to is this.  
[https://download.autodesk.com/us/revit/OmniClassTaxonomy.txt](https://download.autodesk.com/us/revit/OmniClassTaxonomy.txt)

In addition, why the numbers provided in this txt are different from the OmniClass list provided by Revit?

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/c/4/c42e89b4a411e9bb3285b33eb2696ebcb18b5dc0.png)

And I found that when opening different family files, the OmniClass list provided by Revit will be different.

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<div class="post-metadata">

**Author:** ![chuongmep](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/chuongmep/32/197537_2.png) [@chuongmep](https://forum.dynamobim.com/u/chuongmep)\
**Post date:** [April 8, 2024, 12:16pm UTC](https://forum.dynamobim.com/t/failed-to-specify-the-omniclass-parameter-value-of-the-family-file/99816/2 "2024-04-08T12:16:04Z")

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did you tried with python script, some thing like that ?

```python
elementType = doc.GetElement(element.GetTypeId())
omniClassNumber = elementType.get_Parameter(BuiltInParameter.OMNICLASS_CODE)
OUT =. omniClassNumber

```

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**Author:** ![pyXam](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/pyxam/32/163009_2.png) [@pyXam](https://forum.dynamobim.com/u/pyXam)\
**Post date:** [April 9, 2024, 5:49am UTC](https://forum.dynamobim.com/t/failed-to-specify-the-omniclass-parameter-value-of-the-family-file/99816/3 "2024-04-09T05:49:43Z")

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You might need to update the taxonomy file associated with revit.

[https://help.autodesk.com/view/RVT/2022/ENU/?guid=GUID-BA0B2713-ADA0-4E51-A7CD-85D85511F3ED](https://help.autodesk.com/view/RVT/2022/ENU/?guid=GUID-BA0B2713-ADA0-4E51-A7CD-85D85511F3ED)

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<div class="post-metadata">

**Author:** ![b10705001F2HWP](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/b10705001f2hwp/32/175165_2.png) [@b10705001F2HWP](https://forum.dynamobim.com/u/b10705001F2HWP)\
**Post date:** [April 9, 2024, 6:49am UTC](https://forum.dynamobim.com/t/failed-to-specify-the-omniclass-parameter-value-of-the-family-file/99816/4 "2024-04-09T06:49:22Z")

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It works! Thank you!