The flag tool: It was created just to give us a tool to end game without the need of kill every one but the winner. Then, players start to use it like a diplomatic weapon and created a simple agreement between players during the game: verbal flags or vflags, using the chat to do it.
Flags or flags are not part of the rules. There is no official position. Its just common sense agreement. Some of us think that vflag to another player mean: I will not be in a position above you. I am one of them. Others think different: flag to another player mean: i will not hit you. And others use both concepts, attending their own interests. Choose yours. There is not only one truth.