01 · The gap
A running total is not a ledger
A khata that keeps one running total per customer tells you someone owes four thousand rupees and nothing about which purchases make it up, so when they dispute it you are back to memory. Here credit is created by the bill that gave it, so every rupee that came from a bill points at a dated bill with items on it.
- Balances built from bills, not from typed entries
- Every amount traces to a dated invoice
- Nothing to enter twice, so nothing to disagree with
- The customer can be shown the bill behind any figure
