If you want a map to support both DM and CTF, for example, you can put "gamemode" "5" in the worldspawn. That means it supports gamemode 1 (DM) + gamemode 4 (CTF). Then you can make all your flags, bases, and team spawns have "gamemode" "4", so they only show up in CTF mode, and create spawns scattered around the map with "gamemode" "1", which will only be present in DM mode.