How to extract edge matrix e from an FEMeshAssociation object in a 3D pde problem?

Here, I want the canonical edge matrix e as in [p,e,t] in a 2D PDE problem, but it turned out to be an FEMeshAssociation object in a 3D problem.How can I extract the edge matrix from this object? The code is as follows.

      W=2; D=2; H=2;
      g = multicuboid(W,D,H);
      model = createpde;
      model.Geometry = g;
      generateMesh(model,'GeometricOrder','linear','Hmax',0.2);
      pdemesh(model)
      axis equal
      [p,e,t] = meshToPet(model.Mesh);