One item in draft-ietf-ipp-ipp-scheme-00.txt that I believe is not
  consistent with HTTP/1.1 - my apologies for not noticing this
  earlier.  Discussing how to construct the HTTP headers when sending 
  via a proxy, the draft says:
>  When an IPP client sends a request via a proxy, such as
>  "myproxy.com", to an 'ipp' URL, such as
>  "ipp://myhost.com/myprinter/myqueue", it MUST open a TCP connection
>  to some port (8080 in this example) on some proxy ("myproxy.com" in
>  this example) with the following headers:
>
>     POST http://myhost.com:631/myprinter/myqueue   HTTP/1.1
>     Host: myproxy.com:8080
  The latest draft (and I don't think this language is new) for 
  HTTP/1.1 in section 14.23 Host:
>> The Host request-header field specifies the Internet host and port
>> number of the resource being requested, as obtained from the original
>> URI given by the user or referring resource
  The Host is not used to specify the proxy - the proxy is not specified
  anywhere in the headers that I can find - the client just sends the
  request there.
  The correct value for the Host header field in the example above
  would be 'myhost.com:631', which may make the example the same as 
  the one above that is direct to the IPP server - which would be right.
-- Scott Lawrence Consulting Engineer <lawrence@agranat.com> Agranat Systems, Inc. Embedded Web Technology http://www.agranat.com/