Hi Mike,
"unknown" is used 39 places in PwgWellKnownValues.xsd
in three spellings - unknown, Unknown, and UNKNOWN
- oof! - needs work here...
In PWG SM, SystemGeoLocation is of datatype "xs:anyURI"
with a reference to RFC 5870 ('geo' URI Scheme). "unknown"
is an obviously illegal value, while the empty string can be and
is construed as "unknown" in MFD Model [PWG5108.01].
Cheers,
- Ira
Ira McDonald (Musician / Software Architect)
Chair - Linux Foundation Open Printing WG
Co-Chair - IEEE-ISTO PWG IPP WG
Chair - TCG Embedded Systems Hardcopy SWG
IETF Designated Expert - IPP & Printer MIB
Blue Roof Music/High North Inc
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On Thu, Sep 15, 2011 at 6:16 PM, Michael Sweet <msweet at apple.com> wrote:
> Ira,
>> Semantically-speaking "unknown" and "no-value" do mean different things:
>> unknown: There is a value but we don't know what it is.
> no-value: We know there is no value.
>> Clearly every printer has a geographic location (and thus a value exists),
> however the value of that location may not be known because nobody has
> entered one and/or the printer has no way to get its location automatically.
> While we certainly could use "no-value" for printer-geo-location and treat
> it as "no value set", I like using a more specific tag if one exists.
>> That said, I wonder - how does the Semantic Model map "unknown" to the XML
> schema?
> (or does it?) If there isn't a mapping of unknown then I would suggest we
> formally deprecate the "unknown" value tag and use "no-value" for
> printer-geo-location as you suggest - it hasn't been used widely (or at all
> as far as I can see) and I don't want to depend on something that can't be
> mapped to another protocol binding.
>>> On Sep 15, 2011, at 3:05 PM, Ira McDonald wrote:
>> Hi Mike,
>> I like all of it, except that in printer-geo-location we should
> get rid of that MIB-centric "unknown" and instead use the
> semantically equivalent "no-value".
>> Cheers,
> - Ira
>> Ira McDonald (Musician / Software Architect)
> Chair - Linux Foundation Open Printing WG
> Co-Chair - IEEE-ISTO PWG IPP WG
> Chair - TCG Embedded Systems Hardcopy SWG
> IETF Designated Expert - IPP & Printer MIB
> Blue Roof Music/High North Inc
>http://sites.google.com/site/blueroofmusic>http://sites.google.com/site/highnorthinc> mailto:blueroofmusic at gmail.com> Christmas through April:
> 579 Park Place Saline, MI 48176
> 734-944-0094
> May to Christmas:
> PO Box 221 Grand Marais, MI 49839
> 906-494-2434
>>>> On Thu, Sep 15, 2011 at 5:56 PM, Michael Sweet <msweet at apple.com> wrote:
>>> All,
>>>> I've received a few queries about how the "unknown" and "no-value"
>> attribute value tags are used in IPP recently. What I've been telling
>> people is basically the following, but I'd like to document this somewhere,
>> perhaps as an errata for one of the IPP RFCs (probably RFC 2911 and 3380)
>> along with some updates to the IPP registry for the affected attributes.
>>>> Comments?
>>>>>> The "no-value" Attribute Value Tag
>>>> This value may be set or returned for any settable Job, Subscription, or
>> Printer attribute. The typical usage is to specify an xxx-default Job
>> Template attribute that has no default value, such as
>> "orientation-requested-default" - in that case the Printer may apply a
>> default based on the document such as automatically applying
>> "orientation-requested" with a value of 4 (landscape) for a landscape
>> document.
>>>> The "no-value" value may also be returned for read-only description
>> attributes that are a mandatory part of an object. For example, the Job
>> object's "time-at-completion" attribute can be returned as "no-value" when
>> the Job has not yet entered a terminating state.
>>>>>> The "unknown" Attribute Value Tag
>>>> This value may only be set or returned for specific Printer attributes.
>> Currently only the proposed "printer-geo-location" attribute has been
>> defined to potentially have an "unknown" value.
>>>>>> __________________________________________________
>> Michael Sweet, Senior Printing System Engineer, PWG Chair
>>>>>> --
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>>ipp at pwg.org>>https://www.pwg.org/mailman/listinfo/ipp>>>>>> __________________________________________________
> Michael Sweet, Senior Printing System Engineer, PWG Chair
>>
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