* @param writeFlags WRITE_MERGED is ignored
         */
        public void markUsed( AcroFields parentFields, int writeFlags ) {
            if ((writeFlags & WRITE_VALUE) != 0) {
                for (int i = 0; i < size(); ++i) {
                    parentFields.markUsed( getValue( i ) );
                }
            }
            if ((writeFlags & WRITE_WIDGET) != 0) {
                for (int i = 0; i < size(); ++i) {
                    parentFields.markUsed(getWidget(i));
                }
            }
        }