There actually WAS a DB9 connector, that is 9 pins in the B-side shell. They were used for manufacturing equipment. They carried 4 high-voltage differential pai

There actually WAS a DB9 connector, that is 9 pins in the B-side shell. They were used for manufacturing equipment. They carried 4 high-voltage differential pairs and a common signal for negotiation/detection. IIRC part of the specification was that the signal pins had to be milled solid parts rather than the much cheaper/more common rolled hollow pins.