6.4.16.1 Compliance is required to be demonstrated
at renewal, annual and intermediate surveys or following a substantial
modification as per 1.3.2. In accordance
with 2.4.5, data is required to be
current; that is within 30 days. Data are required to be current;
that is within 30 days. Data is required to be retained on board for
at least three months. These time periods shall be taken to be when
the ship is in operation. Data within that 30-day period either may
be collected as a single test sequence across the required load points
or may be obtained on two or more separate occasions when the engine
load corresponds to that required by 6.4.6.