The document discusses different security levels for ships and ports, including levels 1 through 3. It provides details on the protective measures that correspond to each security level. Security level 1 is normal everyday security, level 2 means there is a heightened threat in a specific area or against a target class, and level 3 means a security incident is probable or imminent. The document also lists examples of security measures that could be implemented at each level, such as access control, monitoring restricted areas, cargo handling, and communication procedures.