The faxed document
Transmission report
The transmission report is the summary printed after a fax is sent: date, time, number called, recipient's identifier, pages and result.
It relies on what the receiving fax machine itself answered during the exchange: at the end of each page, the receiving machine confirms or denies correct receipt. An 'OK' result means every page was confirmed by the machine called, not that a person read them.
Why it matters for fax
It is the document you produce to show that a fax was sent and received by a fax machine. Courts assess its weight freely; it is all the stronger when kept intact, linked to the document sent and consistent with the recipient's displayed identifier.