General Remarks on PP Attachment
There are some limitations to the method by Hindle and Rooth:
Sometimes information other than v, n and p is useful.
There are other types of PP attachment than the basic case of a PP immediately after an NP object.
There are other types of attachments altogether: N N N or V N P. The Hindle and Rooth formalism is more difficult to apply in these cases because of data sparsity.
In certain cases, there is attachment indeterminacy.