Administrative Regulations on Radio Waves Article 45

The allocation of the call sign shall be made in accordance with the Allocation Table of the Call Sign of Radio Stations as established by the competent authority after considering the International Radio Regulations, and shall use the following three parts:1. BAA-BZZ2. XSA-XSZ3. 3HA-3UZ
中文原文 電波監理業務管理辦法第45條
呼號之分配,依主管機關參照國際無線電規則所定之我國各類電臺呼號分配表,使用下列三部分:
一、BAA-BZZ二、XSA-XSZ三、3HA-3UZ

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