Multiplayer Attack/Defence commands [Help needed]

[Freezr]

Good day to everyone,
On many MP games, I have seen players in an alliance use commands for pointing at a certain province to help teammates understand what to attack or defend by using a command of sorts. Could anyone give me any info on how to use these commands, since I have not found any help searching online thus far?

 

[Bunnytob]

IIRC: Ctrl + Click and Ctrl + Alt + Click.
(You can use the commands in singleplayer too if you want/need to practice.)