Additional Military Layers (AML)
NATO officially defines it as a unified range of digital geospatial data products designed to satisfy the totality of NATO nonnavigational maritime defense requirements.
Chart
A chart is a geographic representation of features and attributes for marine navigation that can be in print or electronic form. Charts can show natural hazards such as water depths and currents; man-made hazards; and navigational aids such as marinas, bridges, and man-made lights.
Compilation scale
The compilation scale reflects the scale at which the geospatial data was originally collected. Scale is the relationship between distance on a chart and distance in the real world. Chart scale is typically expressed as a representative fraction or ratio (1/1,000 or 1:1,000). The value expresses that 1 unit of measure equals 1,000 of the same units on the actual surface of the earth. With this in mind, real-world phenomena can be depicted proportionally smaller but accurately. When compiling data, the scale used to represent real-world features must be consistent to ensure their spatial distribution is preserved.
The compilation scale is an attribute used in the multiscale NIS environment to define the scale of data. This attribute can be used to filter the data for display (to ease editing) or for controlling which data is extracted to a product. In addition to the attribute stored at the feature level, a Compilation Scale Value exists to ensure that new data being incorporated into the NIS is tagged with its corresponding scale.
Conflation
The process of reducing multiple representations of the same real-world object into a single record.
Electronic Navigational Chart (ENC)
Digital navigational charts in vector format that provide Notice to Mariners corrections and other important updates to support marine transportation.
Inland Electronic Navigation Charts
Digital navigational charts in vector format that provide river transportation information similar to ENCs.
Nautical Information System (NIS) database
The location for the storage of data that will be used to create navigational products for production.
New Edition (EN)
An existing chart with extensive updates that is republished electronically or in hard copy. An ENC New Edition (EN) is a base file in the S-57 format.
Reissue
An ENC base file in which the UPDN (update number) and EDTN (edition number) values do not change. Conversely, when a new edition dataset is produced, the EDTN usually increases by 1, and the UPDN rolls back to 0.
Revision (ER)
An ENC Revision (ER) is an update to a base file that is commonly called an EN. ER files are considered update dataset types in the S-57 specification.
Scale band
The range of compilation scales appropriate for a specific digital or electronic product.
Source
A wide array of information used to drive the compilation or maintenance of geospatial data. Examples of source range from surveys and imagery to blueprints, letters, and ASCII files.
Structure-Equipment
The structure-equipment term refers to hierarchical S-57 relationships. Historically, these have been referred to as master-slave relationships.