An ENC will be presented, together with its updates, in a SENC (System Electronic Navigational Charts).

The methodology for presenting ENC data for voyage planning or for the voyage on the screen is not explicitly defined in IMO Performance Standards for ECDIS, and each ECDIS manufacturer will deal with this in different ways.

Two different approaches, discussed in more detail, follow:

• Data for ENCs with a better Usage Band will be presented as early as possible and overlap the previously displayed ENC. This could result in an information overflow. To counteract this, Scale Minimum attributes for certain objects are given, helping to avoid such an overflow. These attributes define in which scale range the object will be presented on screen.
• Data for ENC with a better Usage Band will be presented as late as possible. The mariner selects at which stage the best ENC Usage Band will be presented. The presentation of better Usage Bands will happen from about twice the scale of the chart, which means that if there is a current scale of 1:50 000 the next better Usage Band will be presented when a scale of 1:25 000 is reached.

Vector chart presentation will not deteriorate if the mariner selects a scale for which the Usage Band was not defined. The chart information presented will only be the optimum available for the current Usage Band selected; this may not be to the level of accuracy required. Therefore a warning system must be in place to inform the mariner when the wrong scale for a Usage Band is selected.

In that case, as requested by the IMO Performance Standards for ECDIS, highlight over-scale patterns or other indications to show the use of wrong scales have to be presented.

The figures display options to indicate incorrect usage of scale ranges.
The different own ship presentation for both scales has been defined in the S52 standard and will be generated automatically by the system.