code: public void setDateIntervalInfo(DateIntervalInfo newItvPattern)
      {
          // clone it. If it is frozen, the clone returns itself.
          // Otherwise, clone returns a copy
          fInfo = (DateIntervalInfo)newItvPattern.clone();
          this.isDateIntervalInfoDefault = false;
          fInfo.freeze(); // freeze it
          if ( fDateFormat != null ) {
              initializePattern(null);
          }
      }
docs: Set the date time interval patterns.
  @param newItvPattern   the given interval patterns to copy.