“…As explained in our previous papers [6][7][8][9], the signs of the various powers of ε in the components of k p (ε, ξ) induce an orthogonal decomposition of H in subspaces H p with ∈ {−, 0, +}, which allows a comprehensive description of our plate models in any theoretically admissible quasicrystallographic classes. We denote by h p the projection on H p of any element h of H. As an example, for p = (0, 1, 2), we have: H − p = (e, g) ∈ H; e αβ = 0, g 2α = 0, g 3i = 0 H 0 p = (e, g) ∈ H; e i3 = 0, g 1i = 0, g 23 = 0, g 3α = 0 H + p = (e, g) ∈ H; e ij = 0, g 1i = 0, g 2i = 0, g 33 = 0 Then, for a given triplet p, the operator Q can be decomposed in nine elements…”