谈及证明条款，首先必须了解“Attestation”一词，这是法律文件中出现频次较高的一个单词，《元照英美法词典》中其对应的中文表达有以下几种，即“见证；证明；联署证明”。

具体含义如下，可供参考：

“Attestation”指在有证人在场的情况下签订契约、订立遗嘱或签署其他书面文件的习惯做法，证人也要在文件上签名，以证明文件内容及当事人签字的真实性。在大多数情况下这一做法仅是为保存证据，其本身并不构成文件的实质内容。但在有些情况下，文件的签署是否有证人见证则是认定其是否有效的一个至关重要的条件，如英国法规定对卖契〔bills of sale〕，授予指定权的契约〔powers of appointment〕，除军人遗嘱〔military will〕以外的任何遗嘱等文件必须有证人见证方有效。在美国许多州，该词也可指认证官员〔certifying officer〕对文件副本的真实性和正确性所作的认证，即认证官员经过将文件副本与其原件相对比后，在文件上签名证明该副本为真实之副本。

Attestation is a formal statement that you make and officially say is true.

相应地，“attestation clause”即译为“证明条款 ”。 

该条款主要指遗嘱或契据等法律文书中的最后条款，写于证人签名之前，内容是证明法律文书签署的过程，目的在于当证明人死亡、缺席或丧失记忆时，仍可以依照该证明条款来证明文书的签署。该条款常常写作「当…的面签署、密封并分发」等类似语词。遗嘱的证明条款有助于进一步巩固该遗嘱符合法定要求的推定。在苏格兰称之为检验条款〔testing clause〕。

It refers to a clause at the end of a document, in particular a will, which sets forth the legal requirements the document must satisfy, states that those requirements have been met, and is signed by one or more witnesses. An attestation clause strengthens the presumption that the requirements have been met. In the statutory law of wills and trusts, an attestation clause is a clause that is typically appended to a will, often just below the place of the testator's signature.

相关例句如下，以便更好地理解该证明条款：

例句1

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed as of the date first above written.

本协议双方于文首规定日期签署本保密协议，以资证明。

例句2

IN WITNESS WHEREOF, the parties have caused this Agreement to be executed by this respective authorized representatives as of the Effective Date first set forth above.

双方促成本协议于上文中规定的生效日起由双方授权代表执行，以昭信守。

例句3

We hereby certify that the above measurements &/or weights of the g(X)ds were taken solely for counting ocean freight in accordance with the provisions of recognized rules concerned.

兹证明上述货物的尺码及/或重量，系根据有关公认规则的规定进行衡量所取得之结果，仅供计算运费之用。