The edit distance is defined as the minimum number of label modifications, node deletes, and node inserts required to transform one tree to another. A label modification is simply a change of the label and entails no modification to the structure. In fact the transformation from the first to the second entails one deletion and one insertion. As you can see by looking at treein, trees are described in two tables. Rows of the table are separated by a newline character.
Labels can be characters, numbers, or strings and can be mixed.
Thus the order of trees in that file is important. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. This support is greatly appreciated.