the other day I happened to glimpse at a paper provided to one of our FEFS. said paper apparently was a refresher (as Kroger loves to do on paper for its employees...) on how to be a FEFS. mentioned 'Batman and Robin' technique.
The floor supervisor in theory queueing customers is "batman" and the self checkout attendant is "robin" supposedly coordinating the queueing of customers by guiding them to open robots and away from qvision managed checklanes.