# IfcRailing proper ownership

**URL:** https://forums.buildingsmart.org/t/ifcrailing-proper-ownership/2651
**Category:** Developers
**Created:** [April 27, 2020, 10:58am UTC](https://forums.buildingsmart.org/t/ifcrailing-proper-ownership/2651 "2020-04-27T10:58:51Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![claimred](https://avatars.discourse-cdn.com/v4/letter/c/e47c2d/32.png) [@claimred](https://forums.buildingsmart.org/u/claimred)
#### Post date: [April 27, 2020, 10:58am UTC](https://forums.buildingsmart.org/t/ifcrailing-proper-ownership/2651/1 "2020-04-27T10:58:51Z")

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As we know, IfcStair can be represented in two ways

> The IfcStair shall either be represented:
> 
> - as a stair assembly entity that aggregates all parts (stair flight, landing, etc. with own representations),  
> or
> - as a single stair entity without decomposition including all representation directly at the stair entity.

However it’s not possible to provide exact IfcRailing ownership data exporting IfcStair like assembly entity. Sometimes it’s important to assign IfcRailing to a particular IfcStairFlight/IfcRampFlight.

My question is, is it semantically correct to connect particular IfcStairFlight & IfcRailing using IfcRelNests without aggregating IfcRailing inside IfcStair assembly?