it is the legend
The part of the map that explains the symbols used thereon is called the "legend".
Map key
map legend
key
Every map is accompanied by a legend or key. The Key is essential since it contains what each symbol on the map stands for. Such symbols may be drawings, letters, lines, shortened words or coloured areas.
The part of the map that explains what the map's symbols mean is called the legend. Besides notating what symbols are included in the map, a map legend also has a device made for measuring distance that shows how many miles to an inch or more.
The title of a map indicates the subject, and it is found in the legend which also explains all of the map symbols.
the key
The key on a map explains what the symbols and images on the map mean.
the legend or key
It 'decodes' the symbols used on the map, and explains the scale of the map.
the key