A client MUST create an incoming payment resource before it is possible to send any payments to the payment pointer.
When a client creates an incoming payment the receiving Account Servicing Entity generates unique payment details that can be used to address payments to the account and returns these details to the client as properties of the new incoming payment. Any payments received using those details are then associated with the incoming payment.
All of the input parameters are optional.
For example, the client can specify an invoice number as the externalRef property of the incoming payment and this can be shared with the account holder to assist with reconciliation.
If incomingAmount is specified and the total received using the payment details equals or exceeds the specified incomingAmount, then the receiving Account Servicing Entity MUST reject any further payments and set completed to true.
If an expiresAt value is defined, and the current date and time on the receiving Account Servicing Entity's systems exceeds that value, the receiving Account Servicing Entity MUST reject any further payments.