he whole node.
  In this case each node has only one port, but you do not want the whole node to act as the one port.
</p>
<p>
  For example, consider how links connect to the nodes when the whole node is acting as a port in one common manner.
  The <a>GraphObject.fromSpot</a> and <a>GraphObject.toSpot</a> are at the middles of the sides.
  Because the height of the whole node includes the text label,
  the middle of the side is not the middle of the "icon", which in this case is a circle.
</p>
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