Copy-proof sheet

摘要: A copy-proof sheet having a longitudinal axis, and being constituted by background at least one latent mark, of the mark formed multi-line images about 65-line 10% which are reproducible on copy obtained from sheet, other fine mesh 150-line not sheet; distinguishable due to difference in color tone; made up line-containing lateral square areas each sides 3 mm long; area lines oriented parallel axis normal axis; squares juxtaposed alternately with an inclination 45° axis.