Abstract: A printed background pattern for a document is described, wherein the pattern masks a copy indicator which is revealed upon making a copy of the pattern using a digital optical scanning means. The background pattern comprises an area of microprinting with a type size having a line resolution of about 20% to about 80% of the resolving power of the scanning means. Preferably, the type size is less than 100 .mu.m. An area of solid line printing is provided within the microprinting which defines the copy indicator. The solid lines have a visual value approximating that of the microprinting so as to be masked therein, and the solid lines are capable of resolution by the digital scanning means.