 The classes of logics we have considered so far are the main classes in what has come to be known as the Leibniz hierarchy because its members are classes of logics that can be characterized by the behavior of the Leibniz operator. We described only the most important classes of logics in the hierarchy. The reader is referred to Czelakowski 2001, Font, Jansana &amp; Pigozzi 2003, Font 2016 and 2022, for more information. In particular, Czelakowski 2001 gathers extensively the information on the different classes of the Leibniz hierarchy known at the time of its publication and Font 2016 is an introduction to abstract algebraic logic very well suited to learn the most important facts about the Leibniz hierarchy and of abstract algebraic logic in general. 