INTERIM CATEGORY OF ZONE OF CONFIDENCE IN DATA (CATZOC) VALUES

The boundaries between Quality of Data (M_QUAL) areas with different CATZOC values
for certain cells have been taken from the Source Data Diagram (SDD) on the equivalent
paper chart and they should therefore be considered to be approximate.
For these M_QUAL areas, the CATZOC values are based on the simplified summary provided
in the SDD and therefore represent the lowest categorisation assigned to any survey in
each defined group of surveys.
The degree of simplification also means that it has not been possible to identify minor
gaps within survey coverage and mariners should be aware that such gaps (where lower
quality survey data has been used in the compilation of the chart) may exist. Adjoining
areas within the SDD that require the same CATZOC value have been joined together into
a single area.
Note that these assessments are based on original survey accuracies and on expectations
of good practice by relevant survey authorities. It is to be expected that some
evaluations may require downgrading once detailed survey information has been examined.
