What does it mean when an endpoint has “mode” at the end?

The "mode" means that, for example, Non-Allergenic Asthma (mode) - J450 includes all patients with J45x longitudinal events that have J450 as their most common code.

Algorithmically, this means you remove the last character of the ICDx code and then grep all the events, count the ratio of ICDx / ICD codes and assign the J450 case if the ratio is > 0.5. If the ratio is < 0.5, it will be assigned J45, then the same is done for J4x (the comparison between COPD and asthma), etc.