Science and technology never stop and the inventor may make unexpected or expected improvements or discoveries related to the invention during the months or years the application is being examined. But one of the PTO's rules states that once an application is filed, “new matter” (i.e., things not disclosed in the specification when the application was filed) cannot be added. What should the inventor do when new aspects of a filed invention come to light, improvements are made during prosecution, or a theory that was presented in the application is proven erroneous? The remedy is to file a continuation application, continuation-in-part application, or divisional application. Continuation applications are used for minor improvements and allow inventors to amend the claims of an earlier patent. Continuation-in-part applications cover major improvements where an inventor feels that he has to amend the claims and the specification of the earlier patent. Divisional applications are used when more than one invention is disclosed in a patent application. Let us discuss these items in greater depth.

6.5.1 Continuation Applications

Continuation applications are patent applications based on an earlier parent application and keep the parent application's filing date and priority date. Continuation applications can be used in many situations, such as when potentially patentable subject matter was disclosed in the specification ...

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