The present invention relates generally to documents such as printed documents. One claim recites a printed document including a machine-readable signal. The document includes: a first set of print structures conveyed with first ink; and a second set of print structures convey with optical variable ink. 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. 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. Of course, other claims and combinations are provided as well.