Picked up a 10oz Foster mint bar today!

Meltdown

I found this today... I thought it was neat and it goes well with my other 5oz piece.
I wish the stamp wasn't quite so soft on the obverse... Also, I haven't seen markings like these on the back before.
Anybody know what they might represent?

OnlyGoldIsMoney

Meltdown, IMO the Foster 10 oz bars (as well as 5 oz) are quite scarce. Nicely done.

I have the triangle with the square on another bar. That one may be a 3 oz Foster but I am not sure without checking at the SDB. I have no idea what those symbols imply.