• Previously, functors between categories and morphisms of diagrams in $\mathbf{Rel}$ (i.e. 1-morphisms of the 2-slice category $\mathbf{Cat} \downarrow \mathbf{Rel})$ were implemented, but in an awkward way. Proper classes CategoryFunctor and CategoryActionFunctor have now been defined for these two types of morphisms, and can be easily manipulated.