Schedule Margin key - Opening Period

Hi Team,

I am configuring the schedule margin key. I have some basic clarification. In schedule margin key we are maintaining "Opening Period". Is this time period relevant only for "In-House Production Items" or also it will applicable to "Externally Procured Items"?

I understood that it is only for "n-House Production Items". Am i correct? Also i understood that this time period is given MRP Controller to convert the planned order to production order. For example, i have executed MRP run today and MRP has created planned order today (13.08.2013). And i have maintained the opening period as 2 days. In this case, How does the opening period time line will propose the dates?

Thanks