Come on guys, are you really "3D challenged" that you cannot understand the simple fact that a tennis racquet only has four distinctive bevels?! While you swing your racquet and play, all bevels may face sky or ground, left or right, front or back.
I agree that using the top/bottom explanation is just fine for explaining grips to kids and beginners, but in a real game you never point racquet head towards you opponent to change grips. You do grip changes "on the fly" and the most important thing is to switch between grips in the most efficient (i.e. quickest) way. And you rarely hit the ball with the same face of the racquet, so "top" and "bottom" bevels change sides numerous times during a tennis match.
Now please tell me what is the difference between these two grips:
1) First supinate your hand and place base knuckle of your index finger on the bevel 5
2) First place the base knuckle of your index finger on the bevel 1 and then supinate your hand.
But for the sake of preventing future noise here - I admit I'm wrong, there are top and bottom bevels and bevels 1 and 5 are clearly not the same thing. Over and out.