mystery seatstay bridge boss?



I have a new touring frame, and there is a threaded boss in the center the
seatstay bridge, facing outwards, perpendicular the the seatstays. What's
it for? Seems too low to be for a traditional cable hanger, unless it
protruded up and out a bit. Perhaps it could be for one of those odd
pivoting type cable hangers you sometimes see on suspension forks...? It
could be for mounting fenders, although in that case I would think that the
boss would face downwards, parallel to the seatstays, although it could be
useful for fenders with a mounting tab I suppose.