To declare an attribute wildcard, use the declaration:
The declaration can appear only within a or declaration.
You are not allowed to create global declarations.
The namespace attribute allows several values:
##any allows attributes from all namespaces to be included as part of the wildcard
##other allows attributes from namespaces other than the targetNamespace to be included as part of the wildcard
##targetNamespace allows attributes from only the targetNamespace to be included as part of the wildcard
##local allows attributes that are not qualified by a namespace to be included as part of the wildcard
Whitespace-separated list of allowable namespace URIs allows attributes from any listed namespaces to be included
as part of the wildcard. Possible list values also include ##targetNamespaceand ##local.