下残 in text on “Jesus-sūtra” (景教)

Question

I've been working my way through some Chinese text, I came to this line here:

祝曰 　　清净阿罗诃 清净大威力 清净（下残） 大秦景教宣元至本经

I can make sense of some of it, but what does the 下残 in brackets clarify in the text?

Thank you for your time.

Answer 1

下 means the following content.
残 means incomplete.

下残 means the following content is incomplete.

Answer 2

it should be treated as remark by someone, that the original text had missing characters / texts.