Vicad doesn't handle precise curves conversion on model to sheet, this is a feature for shark only, so, arcs and splines are only acquired on model to sheet in shark, on VIACAD you can only get polylines

See description on advance drafting notes

http://www.punchcad.com/c-30-compare-viacad.aspx
http://www.punchcad.com/c-29-compare-shark.aspx

Luis G