Digital Watermark

A unique identifier that becomes part of a digital document and cannot be removed. The watermark is invisible to the human eye but a computer can analyse the document and extract the hidden data. Digital watermarks are being used for Classified/Top Secret documents - usually Military/Governmental - and highly confidential commercial material. The primary use of such marks is to allow different marks to be used when the document is copied to different persons and thereby establish an Audit Trail should there be any leakage of information.