A method for printing indicium on an article including steps of providing a supply of ink including a multi-signal transmission ink which is adapted to provide an optically visual signal when viewed in normal daylight and adapted to provide a different signal which is adapted to be machine readable; and printing at least a portion of the indicium on the article by halftone printing the multi-signal transmission ink. The portion is adapted to be visually observable in normal daylight. The portion is adapted to be read as a non-halftoned signal by a machine even though the portion is halftone printed.