Is a unit considered defending if a showdown isn't happening, specifically for abilities that trigger when defending?

Ruling: A unit is only considered defending when there is a showdown involving units from 2 players (a combat). If there is no showdown, or if the showdown is not a combat between two players (like an open showdown), units are not considered attackers or defenders.

Nuances:

• Open showdowns do not define attackers or defenders
• A showdown must be a combat between two players for defender status to apply