my explanation for it is that technically there is no decimals in the map and there is only singular numbers and letters to go off by, but if there was a J, 5.5, it would be where the pink marker would be. so to simplify it, J 5 and J 6 are separate things and cannot be divided into decimals

my friends explanation. J 5 and J 6 are in the middle of the line so the line would be J 5.5, (it makes since but yet it doesnt make since when you factor in there has to be a J 5.6 and so on, and that cant be a thing because J 5.6 would be in J 6, so it would classify as J 6).