Which is the valid issuing date in a B2B invoice?

According to the decree released by Agenzia delle Entrate on April 30 2018, the valid invoice issuing date is the one typed in the "Data" field in the "General Data" section of the XML document.

If the electronic invoice is rejected by Sistema di Interscambio, we can consider the invoice unissued. The sender receives a rejection message in 5 days and he will have to send the correct invoice again.