When units move to an empty battlefield, are they considered 'attacking' or an 'attacker'?

Ruling: No, units moving to an empty battlefield are not considered attackers. Attacker and defender designations only exist in combat.

Nuances:

• When moving to an empty battlefield, no combat happens at all
• Combat only occurs when moving to an occupied battlefield
• When combat does occur, it consists of the showdown step, combat damage step, and combat resolution step