Stitching On Addy Cloth

Has anyone ever stitched an afghan on addy cloth? I want to stitch the Snow Buddies from Stoney Creek. The model was stitched on 18 ct. addy cloth. When I looked up this fabric, it said the outer area border was the stitching area. So what about the part of the chart that is stitched in the center? Is it also made for cross stitching? If anyone has any answers or knows where I can find some information please post a comment. I have searched the web and can not find anything helpful. Also, has anyone ever stitched Snow Buddies on a different type of afghan? I thank you and appreciate any help you could give.