I just signed up for an ExpertFlyer subscription, and I wonder if someone could help me interpret the result of a search.

Since I know that DL doesn't have GUC inventory showing on ExpertFlyer, I searched KLM for the following fare class: "Business - Upgrade with DL SWU/Global Upgrades & Fare Class" for a flight from SFO-AMS.

Along with the standard non-stops from SFO-AMS on KLM, there are a bunch of DL codeshares, for example SFO-SEA-AMS and SFO-DTW-AMS that also show up with availability (or so I think it says).

Does that mean if I book with KLM I can use Delta GUCs, even on the flights that are code shares on Delta metal? Conversely, does that mean that there's Delta availability on those same flights if I book with Delta? I wouldn't think that it would be that easy to get around Delta's "No Upgrade Inventory on ExpertFlyer" rule.

Any help interpreting would be great.