txInfo internal timestamp

What is the “internal” timestamp that is reported in txInfo (and rxInformation, as well) in reference to? For example, does the time start ticking when the first transmission is sent (received)?

Thanks!

It relates to https://github.com/Lora-net/packet_forwarder/blob/master/PROTOCOL.TXT#L135. It is an internal timestamp known by the gateway without any further meaning you can derrive from it. This timestamp is used to schedule the downlink transmission.