Excuse me, I had seen it but then I forgot to answer when I started to write the post with many answers.Merci Luis pour toutes les réponses et solutions.
Il me reste une question, sans réponse, au post #158 !
That connector is for an extension that is not finished, and I don't know if it's really interesting either, but I decided to send the MCDUs with the possibility of having that extension just in case.
In that connector you can put an infrared module to control the screen with a remote control.