title: GraphViz custom back arrow
body: <p>I have the following code:</p>
  
  <pre><code>digraph "Classes utilisées par Git"
  {
      subgraph mother
      {
          O [shape=record, label = "{GitObject| ref (sha1)}"];
      }
      subgraph herited
      {
          rankdir=LR;
          rank="same";
          "Tree" [shape=box];
          "Tag" [shape=box];
          "Blob" [shape=box];
          "Commit" [shape=box];
      }
      O -&gt; "Tree" [arrowhead="onormal", dir=back];
      O -&gt; "Blob" [arrowhead="onormal", dir=back];
      O -&gt; "Commit" [arrowhead="onormal", dir=back];
      O -&gt; "Tag" [arrowhead="onormal", dir=back];
      "Tree" -&gt; "Tree" [arrowhead="vee", label=" 0..*\n0..*1"];
      "Tree" -&gt; "Blob" [arrowhead="vee", label=" 0..*\n1"];
      "Commit" -&gt; "Tree" [arrowhead="vee", label=" 1..*\n1"];
      "Tag" -&gt; "Commit" [arrowhead="vee", label=" 0..*\n1"];
  }
  </code></pre>
  
  <p>which gives me:</p>
  
  <p><img src="https://i.stack.imgur.com/4vNzj.png" alt="enter image description here"></p>
  
  <p>I works well but arrows in direction of GitOject are not onormal, is their a way to fiw that?</p>
  
  <p>For your help,
  Thanks by advance.</p>