RPG Architect supports accessing actors (entities, vehicles, heroes, and more) in a multitude of ways, largely based on the Variable or Value construct.
Party is used to access a member of the active party. The first party member would be accessed by 0, the second by 1, and so forth.
Entity is used to access an entity in a scene, if valid. The value corresponds to the entity ID.
Self is used to access the entity that is currently being scripted. No further parameters are needed.
By Unique ID is a powerful construct that allows you to save the unique ID of an entity, vehicle, hero, and so forth -- and then access it. Every physics-interactive object in the engine has a Unique ID.