Northrop Grumman Sperry Marine VisionMaster FT, User Manual

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Charts Radar/Chart Radar User Guide
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Official and Unofficial Chart Data
Chart databases may be classified as Official or Unofficial chart data.
Official chart data is known as Electronic Navigational Chart (ENC) data. All
official ENC chart data must comply with data standards set by members of
the International Hydrographic Organisation (IHO) and published in their
document S-57, Edition 3.
An unofficial chart database is data which does not comply with the S-57
Edition 3 document.
An
Unofficial Data permanent prompt is shown whenever chart data from
an unofficial source is displayed (for example, SevenCs World Map charts).
Unofficial data is not certified for safe navigational and the operator should
refer to paper charts for unofficial data regions.
SevenCs supports both official and unofficial data. The official boundary
line is always displayed to distinguish official and unofficial data, unless it
has been explicitly disabled by the operator using the `Official Boundary'
custom chart setting for the SevenCs engine, see Settings.
Certain C-Map chart databases include a combination of official and
unofficial chart data (see footnotes on the previous page). While all types
are used for safety checking, only official ENC data can satisfy the ECDIS
requirements that may in some cases allow a vessel to navigate without
reliance on up-to-date paper charts.
Even when official ENC data is used the operator should be mindful
of the quality of data, and is encouraged to view the data quality
symbol at appropriate intervals and understand the meaning of these
symbols.