code: final public QualifiedName stringToQualifiedName(String str, org.w3c.dom.Element el) {
          if (str == null)
              return null;
          int index = str.indexOf(':');
          if (index == -1) {
              QualifiedName qn = pFactory.newQualifiedName(el.lookupNamespaceURI(null), // find default namespace
                                                           // namespace
                                                           str,
                                                           null);
              return qn;
          }
          String prefix = str.substring(0, index);
          String local = str.substring(index + 1, str.length());
          String escapedLocal=qnU.escapeProvLocalName(qnU.unescapeFromXsdLocalName(local));
          QualifiedName qn = pFactory.newQualifiedName(convertNsFromXml(el.lookupNamespaceURI(prefix)), escapedLocal, prefix);
          return qn;
      }
docs: Converts a string to a QualifiedName, extracting namespace from the DOM.  Ensures that the generated qualified name is
  properly escaped, according to PROV-N syntax.
  
  @param str
  string to convert to QualifiedName
  @param el
  current Element in which this string was found (as attribute
  or attribute value)
  @return a qualified name {@link QualifiedName}