only the boxes at DAR are GA. each box has 5 seats. in your case, you are guaranteed a seat in box 29, but not a specific seat in box 49. if your friend wants to join you, he/she needs a ticket for box 29. get there early and get the best seats in the box (i.e. along the front or side, for the best view).
other than the boxes, everywhere else in DAR = assigned seating.