Head

I'm not sure I like "untouched" as it suggests that node identity
will remain unchanged and I'm not sure we can make that guarantee.

> Any input document passed to the output is untouched by this step.
> That is, for those matching documents in the input sequence, a
> verbatim copy is produced in the output sequence.

I'd prefer:

Any input document in the head of the sequence is reproduced on
the output port as if it had passed through the p:identity step.

                                        Be seeing you,
                                          norm

-- 
Norman Walsh <ndw@nwalsh.com> | The great man is he who has not lost
http://nwalsh.com/            | the heart of a child.-- Mencius