dot/trpl17-09.dot

digraph {
   rankdir = LR;
   overlap = false;
   dpi = 300.0;
   splines = false;
   cluster = true;
   newrank = true;
   outputorder = in;
   compound = true;
   labelloc = "c";
   
   node [shape = "plaintext";];
   
   pinned_box [label = <<table border="0" cellborder="1" cellspacing="0">
      <tr><td sides="B">Pin</td></tr>
      <tr><td port="source"> </td></tr>
      </table>>;];
   
   subgraph cluster_both {
      peripheries = 0;
      
      
      
      string1 [label = <<table border="0" cellborder="1" cellspacing="0" bgcolor="lightgray">
         <tr><td colspan="8" sides="B">s1</td></tr>
         <tr>
         <td port="target">5usize</td>
         <td>h</td>
         <td>e</td>
         <td>l</td>
         <td>l</td>
         <td>o</td>
         </tr>
         </table>>;];
      
      subgraph cluster_deref {
         style = dashed;
         label = "String";
         peripheries = 1;
         
         pin [shape = "point";];
         
         string2 [label = <<table border="0" cellborder="1" cellspacing="0">
            <tr><td colspan="8" sides="B">s2</td></tr>
            <tr>
            <td port="target">7usize</td>
            <td>g</td>
            <td>o</td>
            <td>o</td>
            <td>d</td>
            <td>b</td>
            <td>y</td>
            <td>e</td>
            </tr>
            </table>>;];
      }
   }
   
   edge [tailclip = false;];
   pinned_box -> pin [tailport = "source:c"; arrowhead = "none";];
   pin -> string2 [headport = "target";];
}