That is, a signature can be signed, which forms a countersignature, but that countersignature cannot be signed again.

也就是说，可以对签名进行签名，形成一个副署，但不能再对该副署进行签名。

youdao

Checks and documents written by family members require a countersignature, for example, while company financials are picked over every month.

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