The D5 reference makes me think of chess, where Black would take the D5 square in the opening.

There's certainly a lot of chess talk about how important D5 is:

The reason d5 is more "important" is simply becuase it is a popular square of contestation in the sicilian, arguably the most popular opening in the world. It is also an important square in many other opening lines such as the queen's gambit, as pointed out above.

Whether or not "important" is the correct word is debatable. Certainly in these sicilian lines, the d5 square is more important than any other central square, but of course d5's importance is dependent on the board position. I would not agree that all center squares are equally important because, for example, d4 is rarely a square that people fight over.

We have the Q-clock as our map. Imagine if the map wasn't a clock, but was a 5D chess board map, since we know Trump is playing 5D chess.

A great short video overview of 5D chess.

Imagine all the Q posts were a list of the moves on the 5D chessboard. If we could lay all the posts out like in that video, then we could see which board has King (or Queen?) moving to D5.