Provided that...是一个普通英文中很少使用的古旧词，但该句型在法律文书，尤其是在合约条款中，广泛使用。其用法与if 或but非常类似，汉语中的意思相当于“倘若/如果”或“但”。该短语放在句首，引导出的是法律英语中的一个条件分句，与if，when 或where引导的法律条件句没有本质上的差异;但如果该短语之前存在一个主句，则它表示的是一个与之前的陈述相反的“例外”， 相当于with the exception of...，但英译汉时不能译成“    ......除外”，而是译成“但”或“但是”，所以法律界通常称这类句子为“但书"（proviso)。例如：
例1
Provided that the acceptance of rent or mesne profits by the Landlord after the expiration of the term of the tenancy hereby created shall not be deemed to operate as a waiver or breach of any of the terms hereof nor as a new periodic tenancy by way of holding over or otherwise. A new Tenancy shall only be created by a fresh tenancy agreement in writing signed by the Landlord and the Tenant.
倘若在本合约规定的租期届满后业主接受租金或中间收益，不应被认为是起了放弃或违背本合约的任何条件的作用，也不应认为是起了作为继续租用或其他的新租期的作用。新租约只能是业主和租户签署的新书面租赁合约。
例2
Any 2 justices of the peace to whom this subsection applies shall when sitting together have all the powers and jurisdiction conferred upon a special magistrate by this Ordinance:Provided that such justices shall exercise their powers and discharge their duties in conformity with any direction given by the Chief Justice and under his general control and supervision. ( Laws of Hong Kong，Cap. 227, Magistrates Ordinance, Art.7[2])
本款所适用的任何2名太平绅士，在联席裁判时拥有本条例赋予特委裁判官的一切权利及司法管辖权：但此等太平绅士须遵照首席大法官的指示，及在他的概括管辖及督导下，行使他们的权力及执行他们的职责。