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An ECA zone is shown in the itinerary as a passing (P) port only when the vessel is moving into that ECA zone from another ECA zone. The itinerary does not show all the ECA zones that the vessel passes by, but instead shows transitions between two ECA zones. This is illustrated in the example below.
Example
Itinerary: CALDERA (COSTA RICA) to WILMINGTON DELAWARE via SAN FRANCISCO
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Finally, there is no ECA zone shown en route to Wilmington. This is because there is no transition between ECA zones. The vessel enters NA 200NM once, but never transitions into another ECA zone; hence there is no display of a passing point from there.