Assistant (W): Can I take some money from the petty cash to buy stamps?
Manager (M): Yes, but you need to write it down in the ledger.
Assistant: How do I do that?
Manager: I’ll show you. In this column, write today’s date, and here, write the expenditure.
Assistant: So just the date and purchase?
Manager: There’s more. Don’t forget the receipt. Number it and put it in the box. Then, write the number as a cross-reference.
Assistant: I get it.
Manager: Finally you need a code. You can look that up here, in the index.
Assistant: I see. So the code for stamps is STP-1.
Manager: That’s right.
Assistant: But why don’t we just use a computer spreadsheet?
Manager: We feel that a hard copy is safer. After all, data on computers can get erased.