MacENC via it's chart manager, shows the cell (chart name) and all the objects it contains. An ENC
unlike a RNC is a database made up of 1000's of objects that can be queried.
From the NOAA ENC Website
ENC Cell Naming Convention: ENC cells are 8 characters long (i.e., US3CA70M)
The 1st and 2nd fields are filled with the country or producer code.
The 3rd field is filled with the navigation
purpose. The U.S. has five classifications.
# 1 is for overview charts with scales ranging from 1:1,500,001 or smaller
# 2 is for general charts with scales ranging from 1:600,001 - 1:1,500,000
# 3 is for coastal charts with scales ranging from 1:150,001 - 1:600,000
# 4 is for approach charts with scales ranging from 1:50,001 - 1:150,000
# 5 is for harbour charts with scales ranging from 1:50,000 or larger
The 4th and 5th fields are filled in the U.S. with the state, territory or region abbreviation.
The 6th and 7th fields are filled with an arbitrary number or letter.
The 8th is filled with the chart's unit of measurement. "M' is for metric.