Tree links, or direct associations, are shown on this slide with solid lines. Mesh links are indicated on the diagram by the dotted lines. A message may take multiple paths, particularly if one path is inaccessible, to ensure that the data reaches the appropriate node with or without passing through the coordinator. In tree routing, the message path follows the direct lines of association, child to parent/parent to child, as shown by the grey arrows. In mesh routing, there are more options along the mesh links and a more direct route can be followed.