MM closing means materials documents can no longer be posted, as there are two open periods in MM - current and previous. FI open period allows FI documents to be posted. You can restrict posting to previous periods for some accounts, like materials, to prevent MM posting until all FI documents are finished. The difference between a blanket purchase order and framework order is that a blanket PO is for consumables with a short validity period and no master record needed, while a framework order has a document type of FO and does not require goods receipt or service entry as blanket POs set purchase limits but not specific deliveries.