A method is described for identifying related pages among a plurality of pages in a linked database such as the World Wide Web. The electroplated layer is formed of a different material than the metal layer. 085 mm or less; and a value obtained by dividing an average convex part surface area Srt in the first cross-section and the second cross-section by an average concave part cross-section Sru in the first cross-section and the second cross-section is approximately 0.