In Patisco's trading document system, IQ (inquiry) is the document initiated by a buyer to ask the seller for pricing; QT (quotation) is the seller's formal price reply; PI (Proforma Invoice) is a preliminary invoice provided by the seller before shipment to confirm transaction terms; PO (PO) is the formal purchase order issued by the buyer after confirming purchase intent. These four document types each have independent workflows in Patisco and can be cross-referenced for tracking.