The Enforcement Rules of the Immigration Act Article 14

Continuous legal residence and legal residence refer to the period of residence completed by the holder of the Alien Resident Certificate, as stated in Paragraph 1 of Article 25 of the Act. The period of residence, completed before the Act goes into effect, may be included in applications for permanent residence.
中文原文 入出國及移民法施行細則第14條
本法第二十五條第一項所稱合法連續居留及合法居留,指持用外僑居留證之居住期間。
其申請永久居留者,本法施行前居留期間,得合併計算。

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