Payment Series (PS)
The Payment Series APIs are offered to you as an integrating Merchant, if you want to manage directly the unscheduled MITs (Merchant-Initiated Transactions). The Payment Series would enable you to group your MITs under a known structure, namely a "Payment Serie" and offers additional linked API methods.
Triggering of the MITs could be done on a timely manner when you wish by calling the Create PS Transaction APIs.