Sample (simplified) Tree

Classic simplified tree diagram of the limerick Warp Speed, Ms
                Bright! that uses a dashed curved arrow to represent the link from the
                note to the term, and a dotted arror to indicate the link from the
                ptr to the Wikipedia article. It is simplified because
              it does not contain attribute (or text) nodes, and is missing an l.

An Introduction to XML, slide 12 of 17