• The rulebook does not say that the calculation requires a subtraction between the requested date-time and the responding date-time. The execution time, and therefore the time-out, can be measured by the Requesting PSP by simply looking at the requested date-time and the time the response was received.
• See the VOP Rulebook paragraph 1.8: the VOP Scheme provides a single set of rules, practices, and standards; it is operated by multiple infrastructure providers chosen by individual Participants as the most appropriate for their needs. The infrastructure is managed outside of the scope of the EPC scheme.
• The VOP API Specifications define that time stamps are to be expressed in UTC. UTC is a global time reference.
• It's a good point to think about the synchronization of the systems. The EPC will request its eligible groups to review the above and evaluate the need for additional clarifications.…
The EPC recommends that all such systems supporting VOP be properly synchronized using a time synchronization protocol such as NTP (Network Time Protocol), which is the widely adopted standard for internet-connected systems.
The use of UTC-based timestamps as defined in the API specifications (RFC 3339) ensures consistency in formatting, while NTP synchronization promotes temporal alignment across systems. While EPC does not enforce specific synchronization protocols, it encourages all participants to adopt these best practices to ensure reliable and auditable processing.