How is timestamp calculated?

The discription of a component includes:
U N mm time_stamp
What is N, mm and how can I convert the timestamp to real time? I could not find the explanation in the doc “KiCad file formate.pdf”

thanks

The timestamp is the hex value of the number of seconds that have elapsed since the Linux Epoch, January 1, 1970 (midnight UTC/GMT).

See: Epoch & Unix Timestamp Conversion Tools

Amazing that there is a website for that!

I guess KiCad will change to a 64 bit timestamp by 2038…

thanks, that’s what I needed