Deciphering radio messages referencing grid numbers

[Coinkidoink]

So quite often with the mod pack i get radio messages reporting various ships in grids and some rough information and i don't understand where that is.

The trouble is that these grids are all numbers like, just making one up here, 419561, but all my maps refer to grids with letters and numbers like AN2441 just making one up again.
I couldn't find any map or documentation that clued me in ingame, how do i read these?

[vanjast]

You're looking for this map.
You'll find a similar version embedded in the map of the TWOs mod.

https://www.subsim.com/radioroom/showthread.php?t=252689

[Coinkidoink]

Ah, thank you very much. Finally i can go see if they are actually there.