Trek emonda slr seatpost minimum insert

[Casio20]

Hi dear Mates,
I'm confused with my trek emonda slr seatmast.
What's the minimum insert?
It's a project one painting, therefore i guess it's maybe over painted!

There is a line with 0 at around 6cm insert
The scale starts at around 3,5cm

Please support, i never used it, just got it very cheap and want to avoid any problems

Thanks a lot