Abstract. Let R be a PID. We construct and classify all coordinates of R [x, y] of the form p 2 y + Q 2 (p 1 x + Q 1 (y)) with p 1 , p 2 ∈ qt(R) and Q 1 , Q 2 ∈ qt(R) [y]. From this construction (with R = K[z]) we obtain non tame automorphisms σ of K[x, y, z] (where K is a field of characteristic 0) such that the sub-group generated by σ and the affine automorphisms contains all tame automorphisms.