digraph feedback {
   subgraph cluster_data {
     Data[shape="none", label=<
     <table BORDER="0">
     <tr>
      <td><u>Data</u></td>
     </tr>
     <tr>
      <td>elts</td>
     </tr>
     <tr>
      <td>MeanWDMass</td>
     </tr>
     <tr>
      <td>SolarMassAbundances</td>
     </tr>
     </table>>];
   }

   subgraph cluster_imf {
      IMF[shape="none", label=<
      <table BORDER="0">
      <tr>
        <td><u>IMF</u></td>
      </tr>
      <tr>
        <td>n</td>
      </tr>
      <tr>
        <td>as</td>
      </tr>
      <tr>
        <td>ms</td>
      </tr>
      <tr>
        <td>Mmin</td>
      </tr>
      <tr>
        <td>Mmax</td>
      </tr></table>>];
   }
   subgraph cluster_lifetimes {
      LifeTimes[label=<<u>LifeTimes</u>>,shape="none"];
   }
   subgraph cluster_snii {
      SNII[shape="none", label=<
      <table BORDER="0">
      <tr>
        <td><u>SNII</u></td>
      </tr>
      <tr>
        <td>Mmin</td>
      </tr>
      <tr>
        <td>Mmax</td>
      </tr>
      </table>>];
   }

   subgraph cluster_snia {
      SNIa[shape="none", label=<
      <table BORDER="0">
      <tr>
        <td><u>SNIa</u></td>
      </tr>
      <tr>
        <td>a</td>
      </tr>
      <tr>
        <td>Mpl</td>
      </tr>
      <tr>
        <td>Mpu</td>
      </tr>
      <tr>
        <td>Mdu1</td>
      </tr>
      <tr>
        <td>Mdl1</td>
      </tr>
      <tr>
        <td>bb1</td>
      </tr>
      <tr>
        <td>Mdu2</td>
      </tr>
      <tr>
        <td>Mdl2</td>
      </tr>
      <tr>
        <td>bb2</td>
      </tr>
      </table>>];
   }


   subgraph cluster_snii_all {
      graph[style="dotted"];
      snii_all[shape="none", label=<
      <table BORDER="0">
      <tr>
        <td><u>An array per element</u></td>
      </tr>
      <tr>
        <td>min</td>
      </tr>
      <tr>
        <td>step</td>
      </tr>
      </table>>];
   }

   subgraph cluster_snii_ej {
      graph[style="dotted"];
      snii_ej[shape="none", label=<
      <table BORDER="0">
      <tr>
        <td><u>Ej</u></td>
      </tr>
      <tr>
        <td>min</td>
      </tr>
      <tr>
        <td>step</td>
      </tr>
      </table>>];
   }

   subgraph cluster_snii_ejnp {
      graph[style="dotted"];
      snii_ejnp[shape="none", label=<
      <table BORDER="0">
      <tr>
        <td><u>Ejnp</u></td>
      </tr>
      <tr>
        <td>min</td>
      </tr>
      <tr>
        <td>step</td>
      </tr>
      </table>>];
   }

   subgraph cluster_coeff_z {
      graph[style="dotted"];
      coeff_z[label=<<u>coeff_z</u>>, shape="none"];
   }

   subgraph cluster_snia_metals {
      snia_metals[shape="none", label=<
      <table BORDER="0">
      <tr>
        <td><u>Metals</u></td>
      </tr>
      <tr>
        <td>elts</td>
      </tr>
      <tr>
        <td>data</td>
      </tr>
      </table>>];
   }

   Data->LifeTimes;
   Data->IMF;
   Data->SNII;
   Data->SNIa;

   LifeTimes->coeff_z;

   SNII->snii_all;
   SNII->snii_ej;
   SNII->snii_ejnp;

   SNIa->snia_metals;
}