JCV Confusion

In my Nuvi 2597, I have USA Maps City Navigator North America NT 2021.1 installed as default (I get the free updates) and I have recently downloaded and installed City Navigator Europe NTU 2020.2 - so both are in he unit memory, not via SD card.

When I view my folders and files, I have the following?
From Root Menu:
Folder - Garmin - Folder JVC (not JCV) - Contains D616504A and D621204A
Folder - JVC (not JCV) - Contains D616504A and D621204A
Folder - MAP - Folder JVC (not JCV) - Contains D616504A and D621204A and City Navigator NTU 2020.20 Image

Within the Europe Maps package that were downloaded, I have the following JCV Files:
D2505280A.jcv and D3084250A.jcv (one is full and one is smaller and I have plenty of space available)

Questions:
1. Are the folder names on my unit wrong and would that stop the JCV files being accessed?
2. Are these JCV files being used by the built-in USA maps?
3. What folder(s) do I need to copy the new JCV files into and should I rename the folders and delete the unnecessary folders?
4. What is the difference between the "NT" and the "NTU" maps?
5. Any other advise of recommendations welcome

Thank you

Answer:
1. The correct folders for JCV (JVC is only a primary manufacturer of multimedia devices) are
\.System\JCV in internal memory
\Garmin\JCV on external microSD
2. The North America NT 2021.10 JCV for your device is D3191310A.JCV, located probably in \.System\JCV folder
3. As stated above in point 1
4. NTU shows correctly Unicode charatters, typical of non latin Languages as Cyrillic, Greek, Polish, and so on. Your device is fully compliant with NTU Maps, but read NT Map as well
5. Take into account what stated above

Note:
the 2 JCV you mentioned reletive to European Maps (D2505280A.jcv and D3084250A.jcv) belong to CN Europe NT 2020.20 Maps, they don't work with NTU Maps
The right JCVs for CN Europe NTU 2020.30 Maps are D6165110A.JCV (All Noth) and D6212110A.JCV (All South)

Thank you for the great information - where can I get the D6165110A.JCV (All Noth) and D6212110A.JCV (All South) from please?

I can only see the Map folder for the Europe maps that I have installed despite setting my folder / file view to show all hidden - not sure why

I therefore believe that when I get the latest JCVs and copy to the correct folder, things should be ok without disturbing the USA maps

Thanks

You can download your JCVs from here: City Navigator Europe NTU 2020.30 UN FID 8360

Garmin Nuvi 25xx serie are MTP Devices, you must enable "Mass Storage Mode" on Device to view \.System folder
To enable the "Mass Storage Mode", like the previous series, proceed as follows:

1. From the Map screen, touch the speed icon to access the Travel Panel.
2. Press and hold the Direction / Speed indicator for about 10 seconds until a hidden Diagnostics menu appears
3. Scroll to "MTP Settings", set to "Mass Storage" and Save settings.
   The Menu should appear like follow
   MTP SETTING
   MTP Auto Detect
   Mass Storage
   Mass Storage Single Session

Now your Nuvì is exactly like those of the old series (including .System folder)