question about mapmanager resource.

[Eth]

Hello guys, I am sorry if I have posted this question on the wrong section, I was confused where to post it . recently I have been trying to understand the mapmanager resource so I followed the tutorial on the wikia about it and it's really great! but here is my question, in the wikia it says:

"Basically, the "onGamemodeMapStart" event gives us the handle of the map ("startedMap"), which we used to extract the handle of the resource containing the map ("mapRoot")."

but let's say I have 3 maps : map1.map,map2.map,map3.map and all of them are attached to the gamemode, which map is going to start and why?