# Entity IM usage of CLUSTER instead ITEM_STRUCTURE

**Category:** [Entity/demographics](https://discourse.openehr.org/c/entity/112)
**Created:** 2025-01-20 14:58 UTC
**Views:** 30
**Replies:** 2
**URL:** https://discourse.openehr.org/t/entity-im-usage-of-cluster-instead-item-structure/6202

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## Post #1 by @Mohammad_Zawahreh

Hi everybody, 
I was recently reading the demographics IM and came across `PARTY` descendant classes like `PARTY`, `ROLE` and  `CAPABILITY`..etc. I notice they depended on `ITEM_STRUCTURE`, which gave me the idea that even those classes can be archetyped and queried.
Then I came across Entity IM (which i think is the the future of Demographic IM?), I found that `ITEM_STRUCTURE` was replaced with `CLUSTER`.

I am new to openEHR so I am sorry If my question is naive, but can anyone explain to me the reasoning and the logic behind that replacement and how it might affect archetyping and quering these classes ?

Thank you in advance

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## Post #2 by @ian.mcnicoll

It was originally thought that a variety of structures eg  list, tree, table woukd be needed but we found that the itemTree pattern was enough .it is structurally identicsl to Cluster  which is used widely so this would have been preferred for new specs.

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## Post #3 by @Mohammad_Zawahreh

Thank you for you reply.

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**Canonical:** https://discourse.openehr.org/t/entity-im-usage-of-cluster-instead-item-structure/6202
**Original content:** https://discourse.openehr.org/t/entity-im-usage-of-cluster-instead-item-structure/6202