XML serialization of list of lists

Hi,

Any clarification on the xml serialization of List of Lists as used in IfcBSplineSurface

The example writes a flat list that isn’t correct.
http://www.buildingsmart-tech.org/ifc/IFC4/Add2TC1/html/annex/annex-e/basin-advanced-brep.ifcxml

Question identified by Thomas on Twitter: https://twitter.com/aothms/status/1034802813837225984

Cheers,

Jon

according to ISO 10303-28 it maps to a single list of Carstesian Points, but you have to add the position numbers, i.e.

<ControlPointsList>
     <IfcCartesianPoint id="i5" pos = "1 1" Coordinates="239.758213537139 192.193559404919 -83.9999999999991" />
     <IfcCartesianPoint id="i6" pos = "1 2" Coordinates="0 275.591853484122 -83.9999999999991" />

it is needed by aggregates of aggregates that do not have fixed upper bounds.