function CEL_OnIncorrectSymbol(Source, EventID, symbl, varargin)

try
    % Informing about incorrectness of given symbol.
    disp(['"', symbl, '" is an incorrect symbol.']);
    CEL_ShutDown;
catch
    CEL_ShutDown;
    disp('An error occurred in CEL_OnIncorrectSymbol.m file.');
end