That's a trim, yes, but it doesn't mean that it will be used. Batman at SFWoA has one leading into the cobra roll, but as far as I know, it has never been used.
Mid-course brakes are intended to stop a train from entering the next block if the train ahead hasn't left it.
They will generally bleed off a little speed as well, but there is a good reason for it. Keep in mind that the rides are designed so a train stopped at the mid-course block can complete the course from a dead stop. To compensate, and keep the trains arriving at a consistent interval, the trains are generally slowed a bit through the block.
-------------
Jeff
Webmaster/Admin - CoasterBuzz.com