Just like Kumato, Zima is not a variety, but a brand. All tomatoes bearing the Kumato brand are produced from the Olmeca F1 variety - which is owned by Syngenta and licensed.
I grow tomatoes commercially - one of the seed reps I deal with told me since then they've wisened up after they made the mistake of registering the Campari trademark and getting caught up in a legal battle with their seed supplier and other growers - they develop their own marketing trademark for something that's out there on the market. That way they get the marketing buzz, and at the same time they throw a curveball at their competitors - it's all in the brand.
http://www.floridafarmers.org/news/a...paritomato.htm