How does “Reviewing and approving” work on the Bills page?

Review on a bill's row records a decision — approved, or a query — with a note and an optional planned payment date. An approved bill's note and date are written to the bill's history in Xero, so anyone reading the bill there sees who approved it and why; the Approval column and the approver filter show the same on this list. Undo approval takes the decision back. A held bill shows its hold badge and reason and is not offered to a payment run until it is released. Where: Bills (/accounts/purchase).