A PRINTED AND ENCODED MASS DISTRIBUTABLE RESPONSE PIECE AND METHOD OF MAKING THE SAME

摘要

A method of simultaneously encoding successive groups of printed paper sheet s or mass distributable material wherein the sheets (20) are provided with unperceptable and virtually invisible common code pattern (30) by laser means (70) which is suppli- ed with a distinct series of coded pulse signals in synchronism with control pulses to produce a different optically-scannable coded hole pattern (30) on each group of printed sheets.