Quote Originally Posted by Ballebar View Post
Since all special versions of cityXplorer for nüvi 3790 have FID = 800 & PID = 1 you will only need one (1) unlock code for all of them. It seems not to be a widely spread knowledge that the "gmapsupp.unl" file can hold all unlock codes in a Garmin GPS unit. If one needs 100 unlock codes for some reason then all can be put inside "gmapsupp.unl".
Great tip! I did exactly the same, but I also went to the extreme to add a comment for each unlock code. Here is what my gmapsupp.unl looks like.

Code:
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Each line starts with 25 characters of unlock code, followed by 23 characters of comments, then followed by a DOS end-of-line (i.e. carriage return + line feed). This format is designed for DOS editors. If you use Unix editors, you can have 24 characters of comments followed by a Unix end-of-line (i.e. line feed only). Or if you use Mac editors, you can have 24 characters of comments followed by a Mac end-of-line (i.e carriage return only).

You can have anything in the comments. I just put MapID and map name. The MapID makes it easy to create a new unlock code for another device without looking up the MapID again. Of course, if 23 characters are not enough for your comments, you can use 23+25, 23+50, ... (in general 23+25*n) characters for comments too. All space of the comments must be filled in. For example, I appended dots to the end of the first line to make the comments 25+23 characters long.

Since each unlock code is in one line, it becomes very easy to add, move and remove unlock codes. If all unlock codes were in one long string instead, it would be very difficult to find where the 50th unlock code starts and ends to remove it.