Compute the Eastings, Northings, OrthogonalHeight from the selected SiteTransformationBasis.

Get EPSG code from SiteLocation.GeoCoordinateSystemDefinition which is a full definition in XML regarding a specific Projected Coordinate System IFC expects only EPSG code as described in teh schema https://standards.buildingsmart.org/MVD/RELEASE/IFC4/ADD2_TC1/RV1_2/HTML/schema/ifcrepresentationresource/lexical/ifccoordinatereferencesystem.htm