Although the Patent Cooperation Treaty means that a single application can result in a patent in all PCT countries, it is not unusual for a patent applicant to file separate applications with more than one patent office at about the same time (or within the confidentiality period for the earlier application.) The difficulty that can arise from a defendant’s point of view is that concurrent applications are not visible on databases such as INPADOC and there may be issues as to whether disclamatory statements in concurrent application have a preclusive effect (e.g., prosecution history estoppel) with respect to the other.