Answer
Alternative Holidays are tracked as days. A positive manual adjustment records a day earned. A Leave Taken row deducts the day when the employee takes the alternative holiday.
To review the balance, open Employees >> Leave >> Leave Entitlement Adjustments >> Balance Breakdown. The same balance is shown on the pay's Leave Balances screen.
When paying an alternative holiday, enter the leave row on the pay with the correct date, unit, quantity, rate, and total amount. The valuation uses the employee's relevant daily pay information and work pattern.