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LC Responses/MS2

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PeterPatelSchneider 13:02, 12 March 2009 (UTC)

Draft Response for LC Comment 8:] MS2

Dear Michael,

Thank you for your message


on the OWL 2 Web Ontology Language last call drafts.

The relevant wording in Syntax has been changed to:

The facet space is a set of pairs of the form <f,v>, where F is an IRI
called the constraining facet and v is an arbitrary data value called
the constraining value. Each such pair is mapped to a subset of the
value space of the datatype.

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Regards, Peter F. Patel-Schneider on behalf of the W3C OWL Working Group

Section 4 of the LC working draft of the Structural Spec makes the following statement w.r.t. facet spaces of datatypes [1]:
    The facet space is a set of pairs of the form < F v >, 
    where F is an IRI called a constraining facet, 
--> and v is an arbitrary object 
    called a value.

I do not understand the meaning of the phrase "arbitrary object" in this context.

(1) Does this mean that arbitrary /literals/ (and nothing else) are allowed, as suggested by the specification of the Direct Semantics of datatype restrictions [2] (only literals are allowed to occur as the values of facets in datatype restrictions)?

(2) Or does it mean that the value for a facet can be both a /literal OR an individual/, i.e. there may be facets restricting a datatype by something else than a primitive data value?

I cannot find any definition of the term "object" in the Structural Specification, or any usage of this term from which the meaning in the above statement would become clearer. However, the term "object property" is used throughout the text, and Section 5.6 on "Individuals" [3] makes the following statement: "Individuals represent actual ***objects*** from the domain being modeled.". So "object" in the context of facet-value pairs might easily be misunderstood to exclusively mean "individual", which is certainly not intended.

My suggestion (editorial change request): In the text on facet-value pairs cited above, replace the term "object" by something that clarifies what is actually meant.

Regards, Michael

[1] <http://www.w3.org/TR/2008/WD-owl2-syntax-20081202/#Datatype_Maps>

[2] <http://www.w3.org/TR/2008/WD-owl2-semantics-20081202/#Data_Ranges>

[3] <http://www.w3.org/TR/2008/WD-owl2-syntax-20081202/#Individuals>