So, they are not differentially heat treated.
They are homogenous. That's what I also found out from this link: http://www.bussecollector.com/INFI/
"INFI is the only knife steel ever tested that has achieved such high levels of lateral strength with a homogenous hardness of 58 - 60 Rc"
But I was not sure.

Thanks for clarifying that, guys!

So, 58-60 is the tolerance area where the blade is and it's intended to be homogenous.