// using XML style syntax // This is a class dictionary that serves the same role // as a UML class diagram or an XML schema ShoeOrder = "<ShoeOrder>" "id=" <id> String "style=" <style> String "<color>" <color> Ident "</color>" "<size>" <size> String "</size>" <width> Width // how many such shoes has each store ordered? ["<stores>" <stores> List(Store) "</stores>"] "</ShoeOrder>". Width = "<width>" W "</width>". W : AA | EE. AA = "aa". EE = "ee". Store = <name> Ident <howManySuchShoes> Quantity. Quantity = Number. List(S) ~ {S}. Main = . visitors SummingVisitor = <total> int.