 "parent" node.
  function makeLinks(model) {
    var linkDataArray = [];
    var nda = model.nodeDataArray;
    for (var i = 0; i < nda.length; i++) {
      var key = nda[i].key;
      if (key === 'Start' || key.length === 0) continue;
      // e.g., if key=="INTJ", we want: prefix="INT" and letter="J"
      var prefix = key.slice(0, key.length - 1);
      var letter = key.charAt(key.length - 1);
      if (prefix.length === 0) prefix = 'Start';
      var obj = { from: prefix, fromport: letter, to: key };
 