I thought about that when I created the Belt categories. From what I recall, the Ice Belt surrounds Datum Earth but I have to check if it's a continuous band or not. I'd have to reread those chapters.
Looking back at the description I've written at the time, there are a lot of assumptions that might not be proven. So I guess a total rewrite of the page might be necessary.
So to answer your question : I don't know :)
Just saw in The Long War - Chapter 57 (p 341) that Datum Earth is indeed an Ice Belt Earths. I guess we can put those Earths in the Ice Belt Earths category and worst case scenario we'll fix it later.
Ice, ice, baby...