DMR members are only allowed to redeem one code, per title, per format, (DVD, Blu-ray, Combo pack, 4K, etc.). Therefore, potential bidders need both pieces of information in order to know whether or not they have already redeemed a code for what you have listed. If you don't know I would suggest that you list as a random or mystery code which normally do not garner as high of bids since the bidder is taking a chance that they may not be able to use it. Plus, without both pieces of information your listing will be repeatedly flagged for "not enough information". Good Luck to you. :)
"DMR code from Cars 3 DVD" or something to that effect would be great! You may want to edit your actual description to include it since many people don't bother to read through all of the comments. :)