The Line Item file contains a record of every product sold. Since a single transaction
can involve one or more products, each record in the Sales Invoice file is associated
with (linked to) one or more records in this file. Notice that the file contains a primary
key comprised of two fields—Invoice Number and Item Number. Both fields are
needed to uniquely define each record in the file. They also provide links to related records in the Sales Invoice and Inventory files. Although financial reporting of sales and accounts receivable information requires only the data contained in the Sales Invoice file, the Line Item file is needed for operational tasks such as billing, customer service, marketing, and auditing. For example, sales details in the file allow marketing to evaluate the demand for its products. These data also provide audit evidence needed to corroborate the accuracy of price times quantity calculations that are summarized in the
sales invoices.