Old Fashioned American Wedding Cake?

Hello! I was wondering if anybody knows the 'white' icing used on old fashioned american wedding cakes. The dry, sweet version of butter cream? My uncle requested that I make the cake for his wedding, and since I am only sixteen, I am not a professional. I suppose that I don't know what the secret code 'white' stands for to pastry chefs....

Anyways, I have a feeling that he is talking about american butter cream, based on the texture he described. He did say however that he wanted a white cake with white icing, not a white cake with vanilla icing, or a vanilla cake with white icing. Is there a variation of butter cream with no flavoring? Or is he just confused about the lack of vanilla is his desired frosting?

Please answer!!! I have to make the cake in about two weeks. THANKS A BUNCH!