This is a train drop-off (aka requester) station for generic schedules.
It automatically balances chests when unloading them. This ensures all inserters can be busy full-time while loading a train, thus reducing load times. Additionally the output belt layout is an 8x8 belt and lane balancer.
Additionally it calculates the amount of trains worth of space of the requested resource. It then publishes this to the green circuit network minus the amount of trains currently en route to us as a negative number. (I.e. it publishes the amount of trains that should get filled up).