[plt-scheme] make-custom-input-port missing?

Hi all,

Why parsing a XML file took from the net with the line (using net/url
collection):
(xml->xexpr (document-element (read-xml (get-pure-port (string->url
server-list-url))))))

The following is returned:
(Data
  ()
  "\r\n\t"
  (FileName () "menu.asp")
  "\r\n\t"
  (Version () "1.1")
  "\r\n\t"
...)

I don't like the "\r\n\t"... I went to net docs:
read-xml : [Input-port] -> Document
        (...)
Any non-characters other than eof read from the input-port will
       appear in the document content.  Such special values may only appear
       where XML content may.  See make-custom-input-port for information
       about creating ports that return non-character values.


But I can't find make-custom-input-port from searching the help desk.

Any suggestions?

Thanks,
--
Paulo Jorge Matos - pocm at sat inesc-id pt
Web: http://sat.inesc-id.pt/~pocm
Computer and Software Engineering
INESC-ID - SAT Group