DRM technology is used to secure protected PDF documents so that they can only be used in accordance with the license terms attached to them.  What this means is that a recipient of a secured document is not able to pass on their licensing authority to a third (or fourth, or …) party.  Indeed, preventing the redefinition of licensing is a critical feature of an ILP system.  Once DRM has established control over the accessibility and licensing rules for document content it is possible to prevent Information Leakage by preventing use that is not authorised or identifying the source of the leak.