As for all entries, item number is the one on the box.
If the number on the box is different than the cart, put the card number in description.
If there is no number on the box, the item number field should be blank.
If you are changing the item number on an entry where it has the cart number in that field, to the number on the box. You need to also then put the cart number in the description field. We do not want people to just change the entry by removing valid information.
Most Nintendo releases are wrong in the DB like this also, but the same applies. If you fix a Nintendo entry to change the item number to the one on the box, make sure to put the cart number into description field too.
EDIT: fixed topic title.