Enforcement Rules for the Document Legalization Act for the Ministry of Foreign Affairs and Overseas Missions Article 5-1

Where proof of authentication proves difficult to affix to the document, or at the request of the applicant, the legalization certificate may be issued for the photocopy of the document instead of for the original or its exemplification after the document has been authenticated in accordance with this Act; a note is to be affixed to indicate that the photocopy conforms to the original or its exemplification and that the original or its exemplification has been authenticated. Other notes may be added where necessary.
中文原文 外交部及駐外館處文件證明條例施行細則第5-1條
申請驗證之文書不宜或申請人請求不在該文書上驗發文件證明書,於依本條例有關規定驗證屬實後,得在該文書之影本上驗發文件證明書,記明影本與原本或正本相符,及原本或正本經驗證屬實,並得為其他適當之註記。

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