Act Governing the Issuance of the Central Government Development Bond for the First Phase National Freeway Construction Project in Taiwan Article 5

The term for redemption of each issue of the Bond is seven years. Starting from the sixth periodic interest payment, principal repayments shall be made in equal installments once every year, until the Bond has been redeemed in full over a period of five years.
中文原文 中央政府興建臺灣區高速公路第一期工程建設公債發行條例第5條
本公債各期債票償還期限定為七年。
自第六期付息起,開始還本,每年平均還本一次,分五年全部還清。

English translation for reference only; the Chinese text prevails. Not legal advice.