The D4 was a gaming convention that was run by the D6 Gaming Club. It took place about six months after I-CON, so that there could be a convention and something to do at the university on the other side of the year. Rumors have it that they planned to call the second one "2D4", the third "3D4" and so on. They had the convention a few times and then it seemed to disappear.
The final D4 occurred in the spring of 2002.