What does service code B6 mean on a 2007 Pilot?

* Replace VTM-4 rear differential fluid: Driving in mountainous areas at very low vehicle speeds or trailer towing results in higher level of mechanical (shear) stress to fluid or frequently fully loaded. This requires differential fluid changes more frequently than recommended by the Maintenance Minder. If you regularly drive your vehicle under these conditions, have the differential fluid changed at 7,500 miles (12,000 km), then every 15,000 miles (24,000 km).