The sales documents you create are individual documents, but they can also be part of a series of related documents. For example, If you save a telephone inquiry in the system. The customer requests a quote, you create by referring to the inquiry. The customer places an order later on the basis of the quotation and the establishment of a sales order with reference to the quotation. You ship the goods and invoice the customer. All these documents refer each other through flow documents.
After delivery of the goods, the customer requests for credit for damaged goods and you create one for free by referring to the delivery. The entire chain of documents. the inquiry, quotation, order, delivery, billing, and free delivery. create a stream of documents or history. The flow of data from one document to another reduces manual activity and makes it easier to solve problems.