code: public static String getAChars(byte[] block, int pos, int length, String encoding) {
          try {
              return new String(block, pos - 1, length, encoding).trim();
          }
          catch (UnsupportedEncodingException ex) {
              throw new RuntimeException(ex);
          }
      }
docs: Gets a string of a-characters. See section 7.4.1.