Cross-cut shredding is a document destruction method where paper is cut both lengthwise and crosswise. The result is small particles that make document reconstruction practically impossible. Security levels per DIN 66399 range from P-1 (strip cut, low security) to P-7 (highest security). For most ISMS requirements, at least level P-4 (cross-cut) is recommended. In your ISMS, define which security level applies to each classification level. Provide shredders at central locations and train employees on proper use — confidential documents do not belong in the regular waste bin.