public String getAttributeEnumeration(String name, String aname) {
        AttributeDecl attribute = getAttribute(name, aname);
        // assert: attribute.enumeration is "ENUMERATION" or "NOTATION"
        return (attribute == null) ? null : attribute.enumeration;
    }
Retrieve the allowed values for an enumerated attribute type.

@param name
           The name of the associated element.
@param aname
           The name of the attribute.
@return A string containing the token list.
src/nu/validator/gnu/xml/aelfred2/XmlParser.java