“…The mechanism of such a discretisation was explained by Date, Jimbo and Miwa [2] from the viewpoint of the theory of transformation groups, motivated by the idea in [21]. Moreover, the q-discretisation of the 2DTL, which is closely related to quantum groups, was also obtained by the bilinear approach in [17]. Another approach to discretise the 2DTL was introduced by Fordy and Gibbons [6,7], where the discrete equation arises as the superposition formula of two Bäcklund transforms for the continuous-time 2DTL on the nonlinear level.…”