      \fitem{max_key}(nim): return the coordinate $x_n$ of the last
      breakpoint o the nim. This coordinate is the sum of $x_0$ (the
      coordinate of the first breakpoint of the nim, and of all
      intervals $d_i$ of the breakpoints $i$. If the nim is vectorial,
      $x_n$ is a tab. See sect.~\ref{sec:nim}.


      %%% -------------------------------------------------------

