  We study the height one, two, three, and four variables in the Abelian
sandpile model. We argue that correlation functions along closed boundaries, as
well as general conformal field theory principles, show that the four variables
are not represented by the same operator along closed boundaries, or in the
bulk. Along open boundaries, we calculate all n-point correlations, and find
that there, all height variables are represented by the same operator. We
introduce dissipative defect points, and show that along open boundaries they
are represented by the same operator as the height variables.
