What regulation states that you call the battery/company to attention when tha commander walks in?

Iv'e looked in AR 600-25 and can't find it. Since I was a private iv'e been told to do it so i understand that it's the norm. But there is an arguement that you dont call the company to attention when an officer not in command comes in that out ranks the commanding officer only an officer that is in command over your commander.