单项选择题 （） means the level for which minimum appropriate protective security measures shall be maintained at all times, threats and exchanging such information with appropriate Contracting Governments.

单项选择题 The additional mark （） in the Classification Certificate for Machinery means propulsion apparatus is remotely controlled on the navigating bridge control station, and engine assembly control station is unmanned periodically.

单项选择题 The additional mark （）in the Classification Certificate for Machinery represents that personnel are watching at engine assembly control station and monitoring all machinery and electronic devices.