ApplePay Recurring Payment Request

We couldn't find a descriptive reply for the following and we wanted to get additional feedback.

We've received a notification about using ApplePayRecurringPaymentRequest in Apple Pay JavaScript for recurring, installment and unscheduled payments. On the page (https://developer.apple.com/documentation/apple_pay_on_the_web/applepayrecurringpaymentrequest) we found a new object (see whole object below) and there are some questions about using and filling the parameters. I hope you will help us for making understanding.

1. The ApplePayRecurringPaymentRequest should be sent only in initial operation?
2. A phrase "required" is meant the parameter is mandatory?
3. Where can we take the lenth for each field?
4. Parameter regularBilling is applied for recurring, installment and unscheduled payments?
5. Parameter trialBilling is applied only for recurring payments?
6. If we sent the regularBilling or trialBilling Apple Pay will authorize a payment automatically without merchant's actions?
7. In which cases do we have to fill ApplePayLineItemType with value “pending”?
8. Parameter amount is whole sum of all payments or current only?
9. Parameter paymentTiming with value:

• 9.1 "immediate" - when does payment occur when the transaction is complete and sequent payments will occur only after merchant's actions?
• 9.2. "recurring" - what the different with "immediate"?
• 9.3. "deferred" - who and how will provide these payments in the future?
• 9.4. "automaticReload" - when should we use this value? (in description it's not clear)

1. If merchant can't provide recurringPaymentStartDate and recurringPaymentEndDate can we leave them blank or not send?
2. If merchant can't provide recurringPaymentIntervalCount can we leave them blank or not send?
3. Could you describe the usecase with using deferredPaymentDate?
4. Could you describe the usecase with using automaticReloadPaymentThresholdAmount?
5. Is billingAgreement mandatory parameter?
6. Can billingAgreement contain URL on agreement?
7. Is managementURL mandatory parameter?
8. What actions can user make on page via managementURL? And which cases are mandatory?
9. Is tokenNotificationURL mandatory parameter?
10. In which cases will we receive a request via tokenNotificationURL?
11. What kind of params specification should be in tokenNotificationURL (names, lenth, type, mandatory)?

dictionary ApplePayRecurringPaymentRequest 
{required DOMString paymentDescription;
required ApplePayLineItem regularBilling;
dictionary ApplePayLineItem

    Unknown macro: { ApplePayLineItemType type; DOMString label; DOMString amount; ApplePayPaymentTiming paymentTiming; Date recurringPaymentStartDate; ApplePayRecurringPaymentDateUnit recurringPaymentIntervalUnit; unsigned long recurringPaymentIntervalCount; Date recurringPaymentEndDate; Date deferredPaymentDate; DOMString automaticReloadPaymentThresholdAmount; };

    ApplePayLineItem trialBilling;



    dictionary ApplePayLineItem;

    DOMString billingAgreement;

    required DOMString managementURL;

    DOMString tokenNotificationURL;};