"""""""""" just have some very slightly wrong flag on one trimming curve: "ON_Brep.m_T[11].m_type = ON_BrepTrim::seam but m_iso is not N/E/W/S_is" - means something like the edge has a flag indicating it's a seam of a closed surface but another flag on it is not set saying that it's an isoparm curve like it should probably be. It's unlikely that will cause you any actual problem.""""""""

Perfect!

""""""""I don't know why that particular trim flag is not set, it could be a bug in MoI's exporter or it could be a bug in the OpenNURBS 3DM writing library that MoI uses to write 3DM files, it would unfortunately take a lot of investigation work to find out more about it."""""""""""""

And again, perfect!

Thanks for taking a look at it for me....