The punching medium is a standardized format for classifying all revenue and expenditure for defense services. It contains all details related to a voucher and serves as the basic document for financial management and budget control. The punching medium identifies the type of expenditure incurred under different budget codes, such as claims, transfer entries, inter-departmental schedules, cash accounts, railway bills, and defense schedules. Transfer entries are used for rectifying previous classifications and adjusting miscellaneous recoveries.