Matching patterns that are created by the interaction of two or more layers, e.g. moiré patterns

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Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency > Testing patterns thereon (G07D7/004, G07D7/005 take precedence) > using pattern matching > Matching patterns that are created by the interaction of two or more layers, e.g. moiré patterns