A key point to keep in mind when amending applications is the doctrine of prosecution history estoppel. Basically, any statement that is made during the prosecution of a patent can be used to limit the scope of the patent claims. This includes statements that emphasize differences between the patent claims and the prior art. This also includes statements that narrow the scope of the patent claims. Consequently, the strategy of swearing behind the reference is the most preferable method of overcoming a novelty rejection.