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Combo Proposal xmlsch-03 xmlsch-04 pfps-13

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Wed, 30 Apr 2003 10:45:24 +0300
To: w3c-rdfcore-wg@w3.org
Message-Id: <200304301045.24660.jjc@hpl.hp.com>


All three of these issues concern the relationship between RDF datatyping and 
XML Schema datatypes.

xmlsch-03 concerns the terms "lexical mapping" "datatype mapping" 
"lexical-to-value mapping"

xmlsch-04 concerns the phase "zero or more" which permits values in the value 
space to have no corresponding lexical forms in the lexical space. This was 
primarily intended for XML Schema Union datatypes.

pfps-13 concerns facets in general

I suggest we accept the need for clarification but make no substantive 
changes. (It is not clear that any of the comments were seeking substantive 
change).

I observe that
 RDF datatyping uses a simplification of the datatyping model in XML Schema

and hence PROPOSE
 - xmlsch-03 - we globally use the term lexical-to-value mapping instead of 
datatype mapping or any other term
 - xmslch-04 - we do not change the definition of value space but add a note 
clarifying the relationship with XML Schema datatypes.
 - pfps-13 is addressed by the same note (very end of this message)

specifically:

OLD TEXT:
[[
RDF uses the datatype abstraction defined by XML Schema Part 2: Datatypes 
[XML-SCHEMA2], and may be used with any datatype definition that conforms to 
this abstraction, even if not actually defined in terms of XML Schema.

A datatype mapping is a set of pairs whose first element belongs to the 
lexical space of the datatype, and the second element belongs to the value 
space of the datatype:

+ Each member of the lexical space is paired with (maps to) exactly one member 
of the value space.
+ Each member of the value space may be paired with any number (including 
zero) of members of the lexical space (lexical representations for that 
value).
]]

NEW TEXT:
[[
The datatype abstraction used in RDF is intended for use with 
XML Schema Part 2: Datatypes [XML-SCHEMA2]. 

A datatype consists of a lexical space, a value space and a lexical-to-value 
mapping.

A lexical-to-value mapping is a set of pairs whose first element belongs to 
the lexical space of the datatype, and the second element belongs to the 
value space of the datatype:

+ Each member of the lexical space is paired with (maps to) exactly one member 
of the value space.
+ Each member of the value space may be paired with any number (including 
zero) of members of the lexical space (lexical representations for that 
value).

A datatype is identified by a URI.

RDF be used with any datatype definition that conforms to this
abstraction, even if not defined in terms of XML Schema.

NOTE: When the datatype is defined using XML Schema:
+ All values correspond to some lexical form, either using
the lexical-to-value mapping of the datatype or if it is a union
datatype with a lexical mapping associated with one of the member
datatypes.
+ XML Schema facets remain part of the datatype and are used by the XML 
Schema mechanisms that control the lexical space and the value space; 
however these facets cannot be accessed by any standard mechanism within RDF.
]]
Received on Wednesday, 30 April 2003 04:45:30 EDT

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