They can be classified as follows: General feature: • overall sentence length • presence of verb-final and verb-second ancestor nodes • "heaviness" both in number of characters and number of tokens  During testing of the extraposition model, the model was consulted for each extraposable clause to find the highest node to which that clause could be extraposed.
the target node for extraposition is the highest node in the parent chain for which the answer to the classification task "Should the clause move from node X to the parent of node X?"