Cubic parameters seems odd

[pjanck]

https://github.com/IFCRail/IFC-Rail-Unit-Test-Reference-Code/blob/master/alignment_testset/IFC-WithGeneratedGeometry/GENERATED__HorizontalAlignment_Cubic_100.0_-300_-1000_1_Meter.ifc#L44

#45 = IFCPOLYNOMIALCURVE(#46, (0., 1.), (0., 0., 0., 0.), $);

Probably there should be non-zero value for the last y parameter?

(Similar issue also for the GENERATED examples.)