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[Bug 1295] [DM] (from XML Core WG) Relation of DM types to Schema types

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Date: Tue, 07 Jun 2005 14:51:20 +0000
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------- Additional Comments From Norman.Walsh@Sun.COM  2005-06-07 14:51 -------
FYI: Minutes of discussion from May 2005:

> d) 1295  nor  Data Mod  [DM] (from XML Core WG) Relation of DM types to
> Schema types

" 2.6.2, xdt:anyAtomicType
xdt:anyAtomicType "is derived from" xs:anySimpleType, but how?
Trivial restriction?  And if xs:string (etc) is derived from
xdt:anyAtomicType, does that mean its {base type definition} is no
longer xs:anySimpleType? ... we considered the theory that
the type system in the Data Model is not the Schema type system, but
an almost isomorphic one that uses the same names.  If this is the
case, it should be made clearer.  (Perhaps it is in the formal

MR: Yes, defined in the formal semantics.

MSMQ: This is a plea for more honesty about the relationship between the QT and
Schema type systems.

Proposal: Change from "derived from simple type" to "subtype of simple type".

[discussion of whether this really addresses the question]
JR: 2.5.4 in XQuery discusses this.  Implies that these are as defined in XSD, 

MSMQ: ...but they are not only defined in XSD 1.1

Don: It's derived by restriction by excluding list and union types. 

JR: DM 2.6.3 we use different shapes for those that come from XSD.  

MSMQ: In general, QT's use of restriction and extension is consistent with
XSD's.  Don's analysis is not based on anything explicit in the documents. 
[Extensional vs intensional subtypes ???]

Karun: There exists a base type in formal semantics
Mary: But it's not called {base-type}

MR: 2.4.1 XML Schema and the QT type system.

MSMQ: Proposes that we go back to asking the editor that we put in wording that
xdt:anyAtomicType "is a subtype of" xs:anySimpleType

[do we define "subtype" anywhere?]

Jim: 8.3.2 in FS

MSMQ: Proposal - In section 2.6.2 of Data Model, in the list of predefined
types, under anyAtomicType, delete "is derived from" and replace with "is a
subtype of." 

Karun: "is derived from" is used all over XQuery.

[more arcane discussion]

Jim: Points us back to Michael's proposal.  Support? 
[Various people say yes].
Karun: prefers status quo, but can live with it.
JR: wait, I want to see ...[looking at 3.1.4 in datamodel] ... thinks we need to
say something about "subtype."

Jim: Hearing some resistance ... 
Norm: Move on, leave open.
Received on Tuesday, 7 June 2005 14:51:26 UTC

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