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IFC schema management and versioning repository
https://technical.buildingsmart.org/
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Outdated specification: semantics of IfcRelNests #21

Open hlg opened 4 years ago

hlg commented 4 years ago

The semantics of IfcRelNests as opposed to IfcRelAggregates was obviously changed in IFC4. While in IFC2x3 the difference was whether the parts and the whole of a composition are of the same or different type, in IFC4 the difference is whether the parts have an inherent order or not. I don't want to debate if a fundamental change of semantics without changing the name of an entity type is appropriate. I just want to point out that the specification lags a bit behind that change: the supertype IfcRelDecomposes still mentions that "Decompositions may be constrained by requiring both, the whole and its parts, to be of the same type - thus establishing a nesting relationship." This will cause confusion.

This was initally reported in the buildingSMART forums.

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