when a player earned a "net cord" point (a point when the ball bounces off the net cord and directly forces his opponent to default), he raises his hand/racket for a sort of apology to his opponent for a such a point. Vast majority of them do it.
What such a gesture actually mean?
-regretting? ("I'll never do it again"
-sorrow? ("I didn't mean it. I will do UE at my very next shott to compensate you"
-announcing his own luck? ("Look, the luck is on my side. You're done"
-unhappiness for a cheap point? (was the point really cheap??)("I feel terrible for making this types of point for myself. My very next point I will do UE to equalise my ruined feelings"
-telling his own skills ("see what I am able to do!!"
Is it a good manner or a bad manner?
Is there any need for the gesture?
Hint: In 80es they never did it.