How COGM is caculate for ETO

Hi Gurus,

My client is following Direct Production Process( special procurement) and production order type is ETO with reference to WBS element. For some orders system taking COGM is planned cost, some order COGM is standard value from material master(when target planned cost is Zero).

I want know the reason for taking Standard value rather then taking target planned value in production order.

Regards,

Sbabu.