[xacml-comment] draft 15 : '@' is wildcard?

Hi folks,

Simon Godik advices me that the draft 15 examples aren't up to date, but
comparing draft 14 with 15 I see that example rule one changed from....

           <Attribute AttributeName="RFC822Name">
               <AttributeValue>*</AttributeValue>
           </Attribute>

to

           <AttributeDesignator 
Designator="//xacmlContext/Request/Subject/Attribute[@DataType='identifier:rfc822Name']" 
DataType="identifier:rfc822Name"/>
           <Attribute DataType="identifier:rfc822Name">@</Attribute>

I'd assumed that '*' was a wildcard for any value. Is that correct?
Has the wilcard character changed to '@'? Is this documented?

Thanks

John