How could I tag a parking zone for unloading only, or loading only?

The wiki outlines parking:side:restriction=loading_only and parking:side:restriction:reason=* tag with values like loading_zone, and passenger_loading_zone. However, according to the wiki, this implies both loading and unloading. But how can one specify a zone which only allows one kind? For example, how could one specify a drop off only zone? For example:

(located here).

I currently have it tagged as parking:right:restriction=no_parking with a new tag parking:right:restriction:reason=passenger_unloading_zone, but I’m not sure about this tag, as it doesn’t exactly allow for the opposite if passenger_loading_zone implies both. Maybe passenger_unloading_only_zone and passenger_loading_only_zone?

Are you sure that “drop-off zone” is literally only for drop-offs? Is there a separate “pick-up zone” nearby? I’m aware of airport terminals having such restrictions (though it’s all very muddled in the era of ride-hailing applications), but elsewhere the point is usually just to keep traffic moving briskly without allowing drivers to sit there waiting.

I don’t know if it is with 100% certainty at the moment, but how could I tag it if it was?

I’d look to see if any departure lane at an airport terminal has been tagged with something specific. So far, basically all I’ve found is this road at the Milwaukee airport that uses loading_only to mean departure drop-offs only.