price, sale_price, and related fields) are decimal values in major currency units. Purchased-voucher and redemption balance fields (initial_balance, current_balance, and purchase_value) are integers in minor units: 2500 with currency GBP means £25.00.
Timestamps use ISO-8601; date-only validity fields use YYYY-MM-DD. Fields documented as nullable may be JSON null. Identifiers are integers but should be treated as opaque stable keys rather than quantities.