Looks to be Delta Premium Select at least on international flights. Also, may be used for Delta Exception Fares which are typically flights booked via travel agents. If your Premium Select itinerary includes domestic, you may be put in Premium Economy. More info here.

Business Elite Latin America (domestic first class seat, Business Elite service)

WARNING! Basic Economy! Medallion members will not receive paid or Complimentary Upgrades to first class, paid or complimentary Preferred Seats, or paid, or complimentary Delta Comfort+™ when flying on a Basic Economy fare. When you purchase Basic Economy, you will typically enjoy our lowest fare, but seats will be assigned after check-in and you will not be able to change or refund your ticket after the Risk Free Cancellation period. Additionally, you will not be eligible for: paid or complimentary upgrades; paid, complimentary or discounted Delta Comfort+™; paid or complimentary Preferred Seats; or same-day confirmed or same-day standby travel changes, regardless of Medallion or other elite status.

This may be part of DELTA PREMIUM SELECT. Seems to be similar benefits as far as 150% MQMs, but only 2x 50lb bags. Also puts you on booking into:DELTA COMFORT+� (W)

Published deeply discounted and/or promotional business class fare, also non published promotional or convention fare in business class. How to find Business Elite "I" fares.

Non-upgradeable transoceanic, UPGRADEABLE domestic. If using miles it's 12,500 SkyMiles each way.

Upgradeable, transoceanic & domestic (also eligible for D511 mileage award domestic upgrade). If using miles it's 12,500 Skymiles each way

Business Elite, transoceanic and domestic when upgraded via System Wide Upgrade or Points award

Non-upgradeable transoceanic, UPGRADEABLE domestic.  If using miles it's 12,500 SkyMiles each way. *Only Medallions receive domestic upgrades on this fare.

Discounted Coach. *Only Medallions receive domestic upgrades on this fare.

Coach (discount web fare. domestic and appears to be international too. see note 2). Award mileage cannot be used to upgrade this class of service. *Only Medallions receive domestic upgrades on this fare.

Comfort+. It's technically a coach seat with more legroom, dedicated overhead bin, and complimentary drinks. This is much like what were previously called Q-up fares which booked in "A" previously, except that it is for Comfort Plus, not first. Even award tickets for Comfort Plus will show W, but is obviously based on N.

Full Fare coach, Upgradeable transoceanic & domestic (eligible for D411 mileage award domestic upgrade) - also used when involuntary rerouting any fare class passenger due to bumps, irregular ops, etc. which could allow an originally non-upgradeable domestic fare to be upgraded after the reclassification (if you are lucky enough to find available inventory under these conditions) Domestic flights only. International IRROPS and Y will most likely not allow you to upgrade to Business using Skymiles