Like all of real manufacturers the Garmin have the own parts catalog for spare parts.

You can see this part numbers for your device in garmindevice.xml:

Code:
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In some case we have the obvious purpose of files with certain part number as in case with GUPDATE.GCD or gmaptz.img.
But there are not so obvious in case of D3527130A.JCV or 006-D4511-02.bin.

I open this thread to help in resolving of unknown file content and his mission. You can find the name of mysterious file from your device in garmindevice.xml and you can send associated PartNumber to here. And we can try to recognize it!