GPSrChive Discussion Forum

So I already have an eTrex SE
I tested all possible variants and found that the GMAPBMAP.IMG file must definitely contain a map with the map ID "CITIES".
The CITIES map may contain:
Codes: 0x0100, 0x0200, 0x0300, 0x0400, 0x0500, 0x0600, 0x0700, 0x0800, 0x0900, 0x0a00, 0x0b00
Kind: Point
Category: Cities
The problem is that the standard map ID can contain only numbers and HEX codes and all sw checks this and won't allow letters to be used. Unfortunately, the "system" map from Garmin uses the letters in the map ID, in our case CITIES. I would need someone with high level knowledge of IMG files to help solve this problem.
Data from the second file F0071BLA.IMG eTrex SE cannot displayed. Maybe we'll see it in some future firmware, but that's just speculation. From my point of view, it makes no sense to deal with this.
I still see the CITIES mod as realistic. It would be good if each country could make its own CITIES.IMG file with all cities and villages, not just a few of the biggest cities.
In my opinion, the biggest shortcoming of the eTrex SE is the lack of POI support.

Did you try the ASCII coding for the map ID?
CITIES = 43 49 54 49 45 53 = 434954494553
F0071BLA = 46 30 30 37 31 42 4C 41 = 4630303731424C41

Not sure if you can add so many characters / such a big number.
Can even add a different one to try out. If it works, you can add custom layers to the map
OTHER = 4F 54 48 45 52 = 4F54484552
It's possible that the SW automatically converts from HEX to ASCII and shows text version of map ID, but when packing/creating a new map it expects "raw" HEX name.
Also possible that the GPS unit (eTrex SE) has a white-list of map IDs, and will not show any random name, just the ones in the list. So "OTHER" or "JOHN" will be ignored.

Worth a try, IMHO