Regulations for Passenger Ship Administration Article 20

The term "the lowest passenger deck" when used herein shall mean the lowest deck below the summer load line used for passengers.
中文原文 客船管理規則第20條
本規則所稱最下層乘客甲板,指夏期載重線下,可供乘客使用之最下一層甲板。

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