From: Utopia Planitia Fleet Yards
All right, nevermind, as per manual, this must be linked to this:
The bottom right panel shows all the convoy routes, unused escorts, and assigned escorts next to each convoy route name. Escorts are a support unit. They can be transferred from one zone to another or removed from a zone and placed in the available pool. Escorts protect convoys from submarine units attacking them. Escorts have no effect on non-submarine naval fleets nor can they be affected by them. Only subs have a small chance of sinking an escort during the convoy attack calculations.
Chancellor Gorkon to Captain James T. Kirk:
You don't trust me, do you? I don't blame you. If there is to be a brave new world, our generation is going to have the hardest time living in it.