RE: element with anonymous type in a group

["Michael Kay" <mike@saxonica.com>]

It's useful to start with the Note in section 3.4.6:

 

<quote>

Note:

The wording of clause 2.1 above appeals to a notion of component identity which is only incompletely defined by this version of this specification. In some cases, the wording of this specification does make clear the rules for component identity. These cases include:

• When they are both top-level components with the same component type, namespace name, and local name;
• When they are necessarily the same type definition (for example, when the two types definitions in question are the type definitions associated with two attribute or element declarations, which are discovered to be the same declaration);
• When they are the same by construction (for example, when an element's type definition defaults to being the same type definition as that of its substitution-group head or when a complex type definition inherits an attribute declaration from its base type definition).

In other cases two conforming implementations may disagree as to whether components are identical.

</quote>

I'm not sure that your example is covered by any of these cases, so one might conclude that the question of identity is unclear in this case.

Michael Kayhttp://www.saxonica.com

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From: xmlschema-dev-request@w3.org [mailto:xmlschema-dev-request@w3.org] On Behalf Of Antoli, Leo
Sent: 25 January 2007 12:15
To: xmlschema-dev@w3.org; xml-dev@lists.xml.org
Subject: element with anonymous type in a group

Hi all,

 

My question is about what happens when an element with an anonymous type is defined in a group. Then when the group is referenced in several locations, is it the same anonymous type or they’re actually different types (of course with the same definition)?

 

When an anonymous type is used (e.g. in a XSLT or XQuery)  XDM (XQuery 1.0 and XPath 2.0 Data Model) says that anonymous types must be given a unique name:

For anonymous types, the processor must construct an anonymous type name that is distinct from the name of every named type and the name of every other anonymous type. [Definition: An anonymous type name is an implementation dependent, unique type name provided by the processor for every anonymous type declared in the schemas available.] Anonymous type names must be globally unique across all anonymous types that are accessible to the processor. In the formalism of this specification, the anonymous type names are assumed to be xs:QNames, but in practice implementations are not required to use xs:QNames to represent the implementation-dependent names of anonymous types.

Imagine we have this schema:

 

<xsd:group name="myGroup">

       <xsd:sequence>

              <xsd:element name="myElement">

                     <xsd:complexType>

                           <xsd:sequence>

                           …………………………………………………………………………………………………………………..

                           </xsd:sequence>

                     </xsd:complexType>

              </xsd:element>

       </xsd:sequence>

</xsd:group>

<xsd:element name="parent1">

       <xsd:complexType>

              <xsd:group ref="myGroup"/>

       </xsd:complexType>

</xsd:element>

<xsd:element name="parent2">

       <xsd:complexType>

              <xsd:group ref="myGroup"/>

       </xsd:complexType>

</xsd:element>

 

 

The question is:

 

Do myElement local element in parent1 and parent2 have the same type? Or are they different as they’re local elements with anonymous types?

 

So should myElement type in parent1 have a different unique-name to myElement type in parent2? Or should they have the same unique name?

 

I mean, is a group like a “copy/paste” so when a reference is done to a group is just like putting the group content there (so it would be like declaring a anonymous type twice)? Or implementation can be a bit “clever” and realise that they’re really the same type even if it’s anonymous and assign the same unique name to myElement type in both parent1 and parent2.

 

 

Thanks a lot.

 

Regards,

Leo Antoli

 

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