Are there rules for Custom Pset naming conventions?

Are there rules for authoring applications when it comes to naming custom Property Sets (psets)? For example, is there a rule that states, “Custom pset names cannot start with ‘Qto_’ because this is reserved for buildingSMART psets only”?

If such rules exist, where can I find them?

Currently, the primary rule is that any custom Pset CANNOT be simply named “Pset_xxxxx”. The prefix must be something, anything, else and may be an identifying name like:


Thank you kindly for the quick reply.
Is there a source you could link or point me to?

It is in the definition of IfcPropertySet itself: IfcPropertySet - IFC4.3.2.0 Documentation (

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