How to set MRP didn't breakdown the subassembly

Q: How to set MRP didn't breakdown the subassembly from sales area

A:  There is a parameter  in MRP can determine breakdown the subassembly or not

The BOM structure like:

Assembly A
      contain Sub-assembly B
      contains Material C

If the switch is enabled, following requirement is displayed: 

Assembly A
Assembly B
Material C

If the switch is disabled, following requirement is displayed:
Assembly A
Assembly B

In this case, Assembly B is no further broken down, Material C is not displayed as requirement.