The scale of the data contained in the cell is dependent upon the navigational purpose (e.g. Overview, General, Coastal, Approach, Harbour, Berthing).

For example:

Chart GB50202

GB = Authorising HO

6 = Berthing, 5 = Harbour, 4 = Approach,

3 = Coastal, 2 = General, 1 = Overview

0202 individual cell number

As the above example shows that when we come to turn layers on and off, we need to ensure first that we understand what scale of chart we are on.

The below example shows that usage bands vary, but the most important element is that you understand you are on the correct scale, the best available, and now can configure the layers of ENC overlays correctly.