Inspection of documents and valuable products for authenticity can be divided into three categories: first line inspection-the inspection of the document or product with the human senses only without additional equipment; second line inspection-the inspection of the document or product with the means of additional tools like a magnifier, an ultra violet source, a bar code reader; third line inspection-the inspection of the document or product in laboratory conditions, using advanced know how, sophisticated means (spectrometers, microscopes, infrared radiation, etc.) and dedicated inspection facilities. It can be argued that first line inspection has a few psychological drawbacks and that machine inspection grants considerably higher security. This may be true, but a major drawback of machine inspection is the current lack of standardization and it cannot be conceived how the many ingenious systems that have been invented can be put to general use. Obvious exceptions are the magnetic stripe and the chip card. However, there is little refuge in providing valuable documents and products with high tech and highly secure machine readable features if not, first of all, their first line public defence is adequately covered. First line security, therefore, is the main subject of the paper.