Half-mast Implementation Regulations Article 9
During half-mast, any flag hung with the national flag shall not be higher than the national flag.
中文原文 國旗下半旗實施辦法第9條
下半旗時，與國旗並列懸掛之旗幟，其高度不得高於國旗。
English translation for reference only; the Chinese text prevails. Not legal advice.