Regulations of Aircraft Registration Article 27

The size of markings for aeroplane and helicopter is as following:1)For aeroplane:(1) Wing markings, the height of letter shall not be smaller than 50 centimeters.(2) Markings for the Fuselage or tail, the height of letter shall not be smaller than 30 centimeters.2)For helicopters markings on the fuselage, tailboom or vertical tail, the height of letter shall not be smaller than 30 centimeters.
中文原文 航空器登記規則第27條
飛機及直昇機之標誌尺寸規定如下:
一、飛機:
(一)機翼之標誌,其字之高度不得小於五○公分。
(二)機身或機尾之標誌,其字之高度不得小於三○公分。
二、直昇機機身、尾桁或垂直尾面之標誌,其字之高度均不得小於三○公分。

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