code: private boolean lowerLevel(Object[] items, int i, int level)
                      throws IllegalArgumentException {
          if (items[i] instanceof String) {
              return false;
          }
          PatternItem item = (PatternItem)items[i];
          char ch = item.type;
          int patternCharIndex = getLevelFromChar(ch);
          if (patternCharIndex == -1) {
              throw new IllegalArgumentException("Illegal pattern character " +
                                                 "'" + ch + "' in \"" +
                                                 pattern + '"');
          }
  
          if (patternCharIndex >= level) {
              return true;
          }
          return false;
      }
docs: check whether the i-th item's level is lower than the input 'level'
  
  It is supposed to be used only by CLDR survey tool.
  It is used by intervalFormatByAlgorithm().
  
  @param items  the pattern items
  @param i      the i-th item in pattern items
  @param level  the level with which the i-th pattern item compared to
  @exception IllegalArgumentException when there is non-recognized
  pattern letter
  @return       true if i-th pattern item is lower than 'level',
  false otherwise