The standard R/3 system uses different number ranges for billing and accounting documents. If you want to make the accounting document number the same as the billing document number, you can adapt the number ranges. Then both the SD and FI teams can refer to the billing document or accounting document without extra steps.
A document number identifies every R/3 transaction. This document principle in SAP ensures the transaction recording and offers traceability back to the originating transactions. Even casual SAP users are accustomed to many document numbers — for sales orders, purchase orders, delivery documents, material documents, accounting documents, Profitability Analysis documents, and so on. Each document type has a number range.
In standard SAP R/3, the number range for accounting documents is different from the corresponding billing
document number range. Invoices sent to customers, therefore, have billing document numbers that differ from both the
accounting document number that is posted to R/3 Financial Accounting (FI) and the billing number. Companies communicate
to customers via billing documents, whereas the finance team primarily uses accounting documents. This difference may
cause communication gaps.