Inforecord Standard Quantity is the standard quantity that is to be ordered from vendor. It does not trigger any PO quantity calculation.
If you are working with MRP you can use reorder point procedure which considers On Order Stock and On Hand stock for creating Procurement Proposals, and set reorder point as 1000 and Lot sizing Procedure "EX-Lot-for-Lot" OR Set Reorder point as 100 and lot sizing procedure "HB-replenish to max stock level" with max quantity specification as 1000
Regards,
Niranjan