How many moves exactly is the longest opening of today !?

I know before a computer era, an opening would usually last 10-15 moves deep and that's it ! After that Middle game began.

Now days it's hard to imagine, that an opening lasts just 10 moves deep , especially on top level chess.

So my question is : 

Basically we all know , that an openings now days last 20-25 moves easily, BUT what is the actual longest opening theory moves possible?  35 , 40 , 50 moves!? Maybe ? 

PLEASE DON'T just guess answer if you really know , thx in advance.

https://www.chess.com/amp/article/the-4-longest-chess-games-in-history

Something like this?

I'm not talking about longest games , I'm talking about longest theory in openings in regards.

No , I'm asking something entirely different here. 

Did you read my post? 

botvinnik semi slav

Maybe the longest game was theory in that line?

How many moves?  What is the longest variation possible?  

Don't talknonsense, entire game was just an opening phase? 

Does any one actually know an answer? 

Panov Endgame Line. The resulting endgame has been analyzed to death and goes as deep as 30-40+ moves in, so it's a good candidate. 

My other guesses would be some of the sharp stuff(Najdorf, KID, etc) or something that has been played a lot for a long period of time e.g Ruy Lopez

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or how about this

I'm not talking about endgame line theory etc.....

I'm talking about JUST OPENING phase. 

16 moves of theory WOW THAT'S AMAZING!  Opening that lasts not 2 or 3 or 5 BUT 16 moves of theory WOW I'M IMPRESSED!  (NOT!)

Read my post again I'm asking about longest theory available today which will be considered an opening .

.....

This is literally all theory...

NO

You still didn't answer my question, I wasn't asking to show me any games I'm asking very straightforward question here HOW MANY MOVES !? Is the longest theory available today in the OPENING  !?