Actually ...it is what is written on the container. It's not necessarily the brand. I've seen it written on many different manufacturers.
Guys, when I've seen Dex/green mixed it's usually a brown mess. Haven't seen it gunk/oat up, but then..maybe I didn't wait long enough. Another thing to keep in mind is most any color coolants have a green tint to them. It's easy to mistake it for green if the system was clean and flushed when it was added.