MRP2 Scheduling

Dear Gurus,

We are maintaining all operation time in routing to schedule the operation. So that we can able to calculate both start and finish dates in Process Order.

Then I want to know, what is the effect of In-house production XXXXX days in MRP2 in scheduling?

as well as What is the effect of Planned Deliv. Time XXXXX days.

Can you able to give any example please to understand above calculation?