How to create a Periodic BSpline Surface with Geom_BSpline Surface ?

Hello,

I am trying to create a BSpline Surface from its definition data (e.g.: poles, weights, knots, mults, etc...) which I extract from a STEP file via a different library (not OpenCASCADE).

Every time the input data refers to a PERIODIC and RATIONAL BSpline Surface, an exception is raised telling me that the input parameters are wrong (Construction_Error). More specifically, it complains about the Multiplicies table (which has a value > degree).

The header of the class Geom_BSplineSurface describes how to create the tables of KNOTS and MULTIPLICIES for the NON-PERIODIC case. However, for the PERIODIC surfaces it just says that "the data structure tables for a periodic BSpline surface are more complex than those of a non-periodic one".

Unfortunately, this description does not clarify the things.

Does anyone have an idea on how the input data should be organized?

PS: Maybe that's not the most appropriate approach, but I'm actually depending on that external library to get the needed data for surface creation...

Thanks a lot in advance.

Best regards,
Fernando