dot/trpl17-05.dot

digraph {
   rankdir = RL;
   overlap = false;
   dpi = 300.0;
   splines = false;
   cluster = true;
   
   node [shape = "plaintext";];
   
   // Group the two together, which results in the desired alignment.
   subgraph {
      // But don't show the frame!
      style = "invis";
      
      fut1 [label = <<table border="0" cellborder="1" cellspacing="0" bgcolor="gray">
         <tr><td sides="B">fut1</td></tr>
         <tr><td>?</td></tr>
         <tr><td port="target">?</td></tr>
         <tr><td>?</td></tr>
         </table>>;];
      
      fut2 [label = <<table border="0" cellborder="1" cellspacing="0">
         <tr><td sides="B">fut2</td></tr>
         <tr><td>0</td></tr>
         <tr><td>1</td></tr>
         <tr><td port="source"> </td></tr>
         </table>>;];
      
      edge [tailclip = "false"; dir = forward];
      fut2:source:c -> fut1:target:e;
   }
}