  Despite being one of the most reliable approaches for ensuring system
correctness, model checking requires auxiliary tools to fully avail. In this
work, we tackle the issue of its results being hard to interpret and present
Oeritte, a tool for automatic visual counterexample explanation for function
block diagrams. To learn what went wrong, the user can inspect a parse tree of
the violated LTL formula and a table view of a counterexample, where important
variables are highlighted. Then, on the function block diagram of the system
under verification, they can receive a visualization of causality relationships
between the calculated values of interest and intermediate results or inputs of
the function block diagram. Thus, Oeritte serves to decrease formal model and
specification debugging efforts along with making model checking more
utilizable for complex industrial systems.
