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[Bug 2032] R-054: Request for clarification of ur-type

From: <bugzilla@wiggum.w3.org>
Date: Wed, 07 Sep 2005 21:08:48 +0000
To: www-xml-schema-comments@w3.org
Message-Id: <E1ED7A0-0007Iq-Pj@wiggum.w3.org>


           Summary: R-054: Request for clarification of ur-type
           Product: XML Schema
           Version: 1.0
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: XSD Part 1: Structures
        AssignedTo: ht@w3.org
        ReportedBy: sandygao@ca.ibm.com
         QAContact: www-xml-schema-comments@w3.org

Given the following definitions from the Structures spec:

"[Definition:] A distinguished ur-type definition is present in each XML 
Schema, serving as the root of the type definition hierarchy for that schema. 
The ur-type definition, whose name is anyType, has the unique characteristic 
that it can function as a complex or a simple type definition, according to 
context. Specifically, restrictions of the ur-type definition can themselves be 
either simple or complex type definitions."


"Each simple type definition, whether built-in (that is, defined in [XML 
Schemas: Datatypes]) or user-defined, is a restriction of some particular 
simple base type definition. For the built-in primitive types, this is the 
simple version of the ur-type definition, whose name is anySimpleType."


Is the ur-type one type or two types? 
>From the first paragraph, the ur-type appears to be one type, with the name 
anyType. But from the second paragraph, anySimpleType is a version of the ur-
type. Does this mean that ur-type is a group of types, which includes both 
anyType and anySimpleType?

Is it "ur-type" or "anyType" that can function as a complex or a simple type 
definition? Or both? 
If "anyType" can act as a simpleType, then is the following valid?

<attribute name="att" type="anyType"/>
Or is anyType considered to be the "complex version" of the ur-type definition, 
and it can only act as a complex type?

See Issue 2 from the following mail:
Received on Wednesday, 7 September 2005 21:08:54 UTC

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