 To each node \(k\) and each \((n+1)\)-ary predicate letter \(Q(\ldots),\) assign a (possibly empty) set \(T(Q, k)\) of \((n+1)\)-tuples of elements of \(D(k)\) in such a way that if \(k \le k'\) then \(T(Q, k) \subseteq T(Q, k').\) Say that: 