How are ENC charts made from ENC cells

[gym]

Hi

I have been trying to understand how ENC charts are constructed from ENC cells.

For example, when I look at US_REGION08 I see a catalog file that includes (among other things) the following two cells:

<cell><name>US4FL1OO</name><lname>Entrance to Tampa Bay - Gulf of Mexico</lname><src_chart>0</src_chart><cscale>80000</cscale>
...</cell>
...
<cell><name>US4FL1PO</name><lname>Entrance to Tampa Bay - Gulf of Mexico</lname><src_chart>0</src_chart><cscale>80000</cscale> ...</cell>

I interpret this to mean that these two cells should be "placed" in the same ENC chart, but I am wondering:

a) is that correct?
b) how does one determine which cells should be placed in which charts.

It's also possible that I have no idea what I am talking about :-)

One other question what is a panel in a cell. The catalog contains things like:

<cell><name>US4FL1PP</name><lname>Entrance to Tampa Bay - The Narrows - Gulf of Mexico</lname><src_chart>0</src_chart><cscale>40000</cscale><cov><panel><panel_no>1...</panel></cov></cell>

And some cells have multiple panels.

thx
gym

[bcn]

ENC charts are cells - not contructed or composed by "sub-cells". Each cell in the NOAA listing is one chart.


There is an effort underway by all Hydrographic Offices to organize the charts or cells as a grid.
Very well to be observed for several US regions. If you have a look at the ENCs distributed by o-chart for OpenCPN you will find the same for many of European waters.



One rule how to delimit cells is that cells for the same usage band - indicated by the digit following the issuer "US""4...." - shall not overlap. This is true as well for border waters where the envolved entities agree who takes responsibility for that cell.