generators.ET0LTreeGrammar:
( { S0, S1, Si1, S, Si, Si1 },
  { F0:4, F:12, Fi:12, Fi1:13, sq:0, -:0 },
  {
    {
      S0  -> F0[S1,S1,S1,S1],
      S1  -> F[sq,sq,Si1,sq,S,S,S,S,S,S,S,S],
      S   -> F[sq,sq,sq,sq,S,S,S,S,S,S,S,S],
      Si1 -> Fi1[sq,sq,sq,sq,Si,Si,Si,Si,Si,Si,Si,Si,S1],
      Si  -> Fi[sq,sq,sq,sq,Si,Si,Si,Si,Si,Si,Si,Si]
    },
    {
      S0  -> sq,
      S1  -> sq,
      S   -> sq,
      Si1 -> -,
      Si  -> -
    }
  },
  S0
)
