SOG S1C Zone Tempered?

[nozh2002]

I read here
http://www.agrussell.com/knives/by_...cialty_knives/sog_20th_anniversary_bowie.html
that SOG S1C knife has a zone tempered 6-3/8" blade of 1/4" thick SK-5 high carbon steel at 57-59 Rc. with a softer inner core for great strength.

I did not found this in any other palce.

1. Is it true and S1C zone tempered?
2. Is S1 also zone tempered?

Thanks, Vassili.