10. A method comprising: providing a first set of print structures on a surface with first ink; and providing a second set of print structures on the surface with optical variable ink, the second set of print structures comprises breaks in one or more lines, with the second set of print structures conveying a machine-readable plural-bit auxiliary signal, the second set of print structure are provided to cooperate with the first set of print structures so that at a first observation angle the first set of print structures and the second set of print structures appear to provide a first visibly perceptible feature, and at a second observation angle the second set of print structures appear less observable so that the first set of print structures and the second set of print structures provide a second visibly perceptible feature.
14. The method of claim 10 where the first visibly perceptible feature and the second visibly perceptible feature are each machine-readable.