why does my sw software apply a weight in the bom when a material has not been selected yet? This gave me and my client "big ones", when it placed an amount of weight much less than proper amount, into the bom. You would think if  material  is not selected at part level,... a arbitrary number would not be parametrically placed into the bom. It was overlooked, not double checked, and was a mistake and cost us big money. If it had correctly said zero, there would not have been a problem.