| http://www.w3.org/ns/prov#value | - FIG. 4 a is a simplified cross sectional view shown in the U.S. Pat. No. 7,047,883, of a printed image 20 that is referred to as a flip-flop, and which is an example of a dynamic optical effect that can be produced by suitably orienting magnetic flakes in a fluid carrier printed on a substrate.
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