15 Where a topography that consists of more than two layers contains confidential information, an application may contain, instead of a complete set of overlay sheets, drawings or photographs as required by section 14, a set that contains the same total number of sheets, drawings or photographs, but that includes a selected number of sheets, drawings or photographs on which is blocked out up to 50 per cent of the total area covered by those sheets, drawings or photographs, if
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(c) the application contains topography design data in printed form for the areas that are blocked out; however, up to 50 per cent of these data may be blocked out, if the application contains four or more integrated circuit products incorporating the topography.