疑难杂句找人译！！
请高手帮忙翻译下面这个句子，不胜感激！
Unless default shall be made in the redemption of this debenture upon such presentation, interest on this debenture shall cease from and after the date of redemption so designated.
其中的default希望能重点解释下。
[用户系统信息]Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; InfoPath.1)
