I think choice "C" is the only conforming implementation. Quoting from
Because of extensibility, any IPP object might receive a request that
contains new or unknown attributes or values for which it has no
support. In such cases, the IPP object processes what it can and
returns the unsupported attributes in the response. The Unsupported
Attribute group is defined for all operation responses for returning
unsupported attributes that the client supplied in the request.
Any request attribute in the Job attributes group is, by definition, a Job
Template attribute. Support for Job Template attributes by a Printer
object is OPTIONAL. If the client does not supply a boolean operation
attribute named "ipp-attribute-fidelity" with value 'true', and a Printer
does not support a client supplied Job Template attribute, the Printer MUST
"Zehler, Peter" <PZehler@c...> wrote:
> I have had some internal discussions around an issue I would like to
> across the IPP WG.
> ISSUE: An IPP Client sends a print request with the
> "ipp-attribute-fidelity" attribute containing a value of 'true'. The
> also supplies the job template attribute "sides" with a value of
> 'two-sided-long-edge'. The IPP Printer does not support two sided
> The IPP Client software generates the request but put the
> "ipp-attribute-fidelity" in the job attributes group instead of the
> operational attributes group. What should the Printer do?
> A) Reject the request with 'client-error-bad-request' since
> "ipp-attribute-fidelity" is in the wrong group.
> B) Reject the job because the printer does not support two sided
> printing. The IPP Printer would accept "ipp-attribute-fidelity" even
> it is in the wrong group. The printer would return a
> "client-error-attributes-or-values-not-supported' error and return the
> "side" attribute and value in the unsupported attribute group.
> C) Accept the job and print it substituting 'one-sided'. The IPP
> uses the defaulted value (i.e. 'false' ) for "ipp-attribute-fidelity"
> it was not an operational attribute. The return code would be
> 'successful-ok-ignored-or-substituted-attributes' and the "sides" and
> "ipp-attribute-fidelity" would be returned as unsupported attributes.
> "ipp-attribute-fidelity" is not a supported job template attribute)
> As an IPP Printer implementer I would chose C. The response informs the
> client that it is in error. The Printer is forgiving and the job is
> printed. The extensibility of IPP is maintained.
> The Implementer's guide with need to be updated to provide a
> on how to handle "misplaced" attributes. There is currently a clause
> lumps "misplaced" attributes with missing or duplicate attributes.
> By the way my email address has changed from Peter.Zehler@u... to
> Peter Zehler
> Xerox Architecture Center
> Email: PZehler@c...
> Voice: (716) 265-8755
> FAX: (716) 265-8792
> US Mail: Peter Zehler
> Xerox Corp.
> 800 Phillips Rd.
> M/S 139-05A
> Webster NY, 14580-9701
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