Re: Boeing XRI Use Cases

John Bradely writes:

> A IRI is NOT a URI,  it would be WRONG to use a IRI in an XML 
> document for name-spacing.
> The XML specs are clear and unambiguous use a URI.

Well, they do seem to me to be clear, but I read them differently than you 
do I'm afraid ;-).  From the XML Namespaces 1.1 Recommendation [1]:

"Abstract: XML namespaces provide a simple method for qualifying element 
and attribute names used in Extensible Markup Language documents by 
associating them with namespaces identified by IRI references."

and indeed the formal definition [2] says:

"[Definition: An XML namespace is identified by an IRI reference 
[RFC3987]; element and attribute names may be placed in an XML namespace 
using the mechanisms described in this specification. ]"

Regarding schemas to validate such namespace names, note that XML Schema 
1.0 Datatypes anticipated IRIs by defining the xsd:anyURI type [3] in a 
manner that effectively allows for IRIs (that's why there's the somewhat 
confusing reference to XLink mapping rules in the 2nd paragraph);  XML 
Schema 1.1 formalizes the connection [4] now that IRIs are "official", 

"[Definition:]   anyURI represents an Internationalized Resource 
Identifier Reference (IRI).  An anyURI value can be absolute or relative, 
and may have an optional fragment identifier (i.e., it may be an IRI 
Reference).  This type should be used when the value fulfills the role of 
an IRI, as defined in [RFC 3987] or its successor(s) in the IETF Standards 

When writing a schema to validate namespace-qualified content, so-called 
"targetNamespace" attributes of type xsd:anyURI are used to specify the 
namespaces to be matched. So, both the specifications for namespaces in 
XML content, and the specifications for the schemas to validate that 
content quite explicitly allow for IRIs.



Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142

Received on Wednesday, 6 August 2008 02:48:39 UTC