Editor is a reference field for all entities and is related to change tracking. An editor is any user who has made a change to the entity (created or updated).
To find all entities that have been changed by a user e.g. Administrator:
Editor = Administrator
To find all scripts that have been edited by members of a group ( e.g. Test Managers):
EntityType = Script AND Editor = MembersOf('Test Managers')
=, IN, !=, NOT IN, IS, IS NOT