What Does [rev] Mean For The Class 43?

What does it mean on the class 43? There's a version that says it and one that doesn't

 

Reversed maybe. So determines which end you drive from.

 

They were usually formed with the first class accommodation at the front when arriving at Paddington, to allow first class passengers to get to the taxi ranks first.

Rev reverses the formation to allows
you to replicate this in scenario planner.