How to enter requirement date of component material in subcontracting process

Hi All,

I'm doing Subcontracting process Im sending ROH material and getting ROH material,

Im not maintaining BOM.

I have to enter component material manually and what is the exactly requirement date here. requirement date is Subcontractor should should receive material before requirement date..

Please tell me what is the requirement date exactly, how it will calculate

thanks and regards..

ramesh reddy