If a player has already been added to your Friends List, his or her nickname will be highlighted in the battle statistics table, battle info and in the chat.

If your friend is in a battle, you will see a link to it in your Friends menu. Battles with your friends in them are always in the top of the list and show the number of friends in them. Currently nickname of your friend over his or her tank in the battle itself is not highlighted.

You don’t need a confirmation to delete someone from your friends list. If you decide to remove a friend, then you will be automatically removed from his or her list as well. Keep that in mind.
That’s it. Now, knowing everything about the Friends System, go to the game and find all your friends!
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你的基友会在战场列表,战场详细和聊天大厅里各种显眼~
在基友列表里,可以看到有在战场中的状态和链接,点击后就跳到战场详细介绍的界面。战斗中的基友会靠前显示。但是目前战场介绍里还不能高亮基友昵称。
删除基友无需对方确认。【好桑心有木有
好了,好友系统大致就是这样了~快加我好友呀~tking123~~~
——from tankionline post bar dedicated client