ISO/IEC 66399 (DIN 21964) defines seven security levels for destroying data using document shredders. The security levels are named by abbreviating the respective type of data carrier and adding ascending numbers from 1 to 7, for example P-4. The rule of thumb is: The higher the number following the P, the smaller the shredded particles and the less likely it is that the information can be recovered. The appropriate security level is determined by the content of the data you want to destroy: the more sensitive the content, the higher the recommended security level.
