Essential Nautical Solution vocabulary

The following nautical terms apply to data, product, and workflow management.

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.

Central Database Repository (CDR)

The central product-neutral database for the enterprise (NIS) implementation of the Nautical Solution.


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.

Learn more about charts

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 that 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 during replication. 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.


In the Nautical Solution context, conflation is the methodology to eliminate or reduce redundant features in a geodatabase.

Continual maintenance version

A version on the production geodatabase that is also referred to as CM. It is used when extensive new source is applied and represents long transaction data. The result will be a New Edition ENC or paper chart.

Electronic Navigational Chart (ENC)

Digital navigational charts in vector format that provide Notice to Mariners corrections and other important updates to support marine transportation.

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.

Inland Electronic Navigation Charts

Digital navigational charts in vector format that provide river transportation information similar to ENCs.

Nautical Information System (NIS)

An NIS includes a CDR, product library, and production geodatabases. Edits made to the product neutral data in the CDR are applied to linked data in the production geodatabases. Consequently, final quality assurance, cartographic finishing, and product publication or export are typical workflows associated with production geodatabases in an NIS.

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.


An ENC base file where 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.

Scale band

The range of compilation scales appropriate for a specific digital or electronic product.


A wide array of information used to drive the compilation and/or maintenance of geospatial data. Examples of source range from surveys and imagery to blueprints, letters, and ASCII files.

Urgent version

A version on the production geodatabase. It is used when updates must be applied quickly, as short-term transactions, for distribution to the nautical community. The result will be an ENC revision file (ER) or a chartlet.