Production order dates

Hi All,

I have a question on Basic start date and Basic finish date in Production orders.

I have a material A0000001 and its inhouse production time is -0- days. eventhough my production order basic finish data & start date takes a long duration.

Is that basic start and finish date is depend on inhouse production time of the production order Header Material or

Is that basic start and finish date is depend on component availability along with inhous eproduction time.

Please correct me if I am wrong and let me know the correct procedure.

Thanks in Advance