Regulations of Aircraft Registration Article 30

All strokes in the letter, numeral and dash should be solid lines, so colored as to sharply contrast the markings against the background.
中文原文 航空器登記規則第30條
字母、號碼及橫劃之筆劃應為實線,其顏色應使標誌與背景明顯反襯。

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