Talk:Rectilinear Steiner tree

MSTST diagram
With the diagram in the article, what is the purpose of the 3rd horizontal line down? The bold horizontal line (in this case) may be at any height from the second dot down to the third dot down without altering any total lengths. What's with this diagram? What point is it trying to make? -- SGBailey (talk) 08:36, 7 April 2012 (UTC)