# Understanding the PropertyUnitData.xml file

**Category:** [Tool Support](https://discourse.openehr.org/c/tool-support/29)
**Created:** 2025-02-02 23:24 UTC
**Views:** 30
**Replies:** 2
**URL:** https://discourse.openehr.org/t/understanding-the-propertyunitdata-xml-file/6259

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## Post #1 by @richard.kavanagh

I am trying to make sense of the PropertyUnitData.xml file, specifically the 'Unit' element.

My confusion is around the use of curly braces (i.e {} )

I see them in the' UCUM' attribute - and assume these are just standard UCUM annotations

![image|690x27](upload://oMm8cWueSTQTH2L4pniY95EfrvE.png)

I also see them in the 'Text' attribute and assume these should be replaced with openEHR terms.

![image|690x20](upload://vhOeNHXnKkMqxFDSEtg5Ko5sM8y.png)

But I'm a little puzzled when I see them in the 'name' attribute. What is their purpose there?

![image|690x185](upload://4E2spSAUur7cyXFNOHMRfxPnAQ3.png)

Is there documentation on this file somewhere - I have looked and have not found any.

Thanks

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## Post #2 by @siljelb

[quote="richard.kavanagh, post:1, topic:6259"]
I see them in the’ UCUM’ attribute - and assume these are just standard UCUM annotations

![image|690x27](upload://oMm8cWueSTQTH2L4pniY95EfrvE)
[/quote]

Correctly assumed.

[quote="richard.kavanagh, post:1, topic:6259"]
I also see them in the ‘Text’ attribute and assume these should be replaced with openEHR terms.

![image|690x20](upload://vhOeNHXnKkMqxFDSEtg5Ko5sM8y)
[/quote]

Again correct, these are for guiding tools like Archetype Designer when the user needs to construct less common unit expressions from atomic units.

[quote="richard.kavanagh, post:1, topic:6259"]
But I’m a little puzzled when I see them in the ‘name’ attribute. What is their purpose there?

![image](upload://4E2spSAUur7cyXFNOHMRfxPnAQ3)
[/quote]
I don't know of any real purpose here. As you can see in Archetype Designer, they're not interpreted in any way for the user interface:
![image|608x500](upload://h71geA3MwGvkrwM3MstjIQDDQ8S.png)
Maybe some of the original creators of Ocean's Archetype Editor are around and can explain the original thinking?

[quote="richard.kavanagh, post:1, topic:6259"]
Is there documentation on this file somewhere - I have looked and have not found any.
[/quote]

I don't know of any either. This file has a long history at least from Ocean's Archetype Editor, and has been adopted as a pragmatic measure to allow simple unit construction in modelling tools to continue, even if maintaining such a file at all by no means is ideal.

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## Post #3 by @yampeku

Name is also used on archetype preview in CKM, which caused me to believe that some UCUM units were wrong in the past. I'm not seeing any benefit of having an additional pseudo-UCUM syntax, as it will cause confusion in the long run

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**Canonical:** https://discourse.openehr.org/t/understanding-the-propertyunitdata-xml-file/6259
**Original content:** https://discourse.openehr.org/t/understanding-the-propertyunitdata-xml-file/6259