How does cancelling a single line (partial cancel) recompute totals, fees, and loyalty?

A customer or operator can cancel a single line of a multi-item order. The line is marked cancelled and the system recomputes the order's totals, any fees, and the loyalty implications, issuing a partial refund for that line while the rest of the order proceeds. This avoids the blunt instrument of cancelling the whole order when only one item is unwanted — the order continues for…

A customer or operator can cancel a single line of a multi-item order. The line is marked cancelled and the system recomputes the order's totals, any fees, and the loyalty implications, issuing a partial refund for that line while the rest of the order proceeds. This avoids the blunt instrument of cancelling the whole order when only one item is unwanted — the order continues for everything else, with money and points adjusted precisely for the removed line.