“…However, that fact is at least consistent with the apparent absence of defects in most of these models, at least of the kind previously considered [9]. On the other hand, there are several types of Bäcklund transformation available in the literature for the Tzitzéica model [12,13,14,15] c and, therefore, one might suppose there should be a generalisation of the defect, at least for this model, and possibly for others. The purpose of this article is to propose a generalisation by allowing a defect to have its own degree of freedom in a certain well-defined manner, which is just general enough to encompass the c Note: the model introduced by Tzitzéica is the a (2) 2 member of the affine Toda collection of field theories and is also known as the Bullough-Dodd or Zhiber-Mikhailov-Shabat equation.…”