In the active cycle the company is the invoice owner (supplier) and must send the invoice to the customer.
In this scenario the incoming invoice is formally verified towards the standard xsd validator. Then, the invoice is digitally signed and is sent to the Public Exchange System (SDI).
The SDI and the recipient, during the process, send various notices that are collected by the system and exposed via API (see Appendix C); these notices change the invoice status (see Appendix A);
The main API calls follow.