1. A printer, comprising: a number of media receptacles to respectively receive respective ones of a number of consumable marking media, each of the marking media having at least one respective spectral distinguishing characteristic, the at least one spectral distinguishing characteristic of each one of the marking media different from the at least one spectral distinguishing characteristic of the other ones of the marking media; at least one printhead operable to selectively form one or more marks with the marking media on a substrate media; and a control subsystem which, for each of a number of pieces of information, selects from the number of marking media available in the printer based on the respective piece of information to be represented and controls the at least one printhead to form the marks on the substrate media with the marking media selected for the respective one of the pieces of information, at least one of the marks including a combination of at least two of the marking media which are not spatially separably distinguishable from one another by an unaided human.