This document provides instructions on maintaining bill-wise accounting details in Tally.ERP 9. It discusses activating the bill-wise details feature, entering new purchase and sales transactions with reference numbers, and making payments against outstanding invoices by reference number. Maintaining bill-wise details allows tracking transactions at the invoice level, including credit periods, outstanding balances, and settling invoices. The document includes examples and practice exercises for creating purchase and sales vouchers with new references and adjusting payments using reference numbers.