Backlund transformations for integrable lattice equations
  We give new Backlund transformations (BTs) for some known integrable (in the sense of being multidimensionally consistent) quadrilateral lattice equations. As opposed to the natural auto-BT inherent in every such equation, these BTs are of two other kinds. Specifically, it is found that some equations admit additional auto-BTs (with Backlund parameter), whilst some pairs of apparently distinct equations admit a BT which connects them. 
James Atkinson