code: void declarePrefix (String prefix, String uri)
      {
                                  // Lazy processing...
          if (!tablesDirty) {
              copyTables();
          }
          if (declarations == null) {
              declarations = new Vector();
          }
              
          prefix = prefix.intern();
          uri = uri.intern();
          if ("".equals(prefix)) {
              if ("".equals(uri)) {
                  defaultNS = null;
              } else {
                  defaultNS = uri;
              }
          } else {
              prefixTable.put(prefix, uri);
              uriTable.put(uri, prefix); // may wipe out another prefix
          }
          declarations.addElement(prefix);
      }
docs: Declare a Namespace prefix for this context.
  
  @param prefix The prefix to declare.
  @param uri The associated Namespace URI.
  @see org.xml.sax.helpers.NamespaceSupport2#declarePrefix