Ddm 4000 midi thru

[Dj.You.S.Bee]

just wondering exactly what this is suppost to do, a normal midi thru takes a signal in and splits it, for example using midi to control more than 1 sequencer, but this makes no sense at it takes 1 in and would just be spitting it back out, if someone could shed some light on this it would be great, is it that the thru takes a signal in and puts it back out? or what, i have no idea, someone who can give a good answer and back it up would be greatly appreciated, thanks

[bartboy]

I'm thinking about picking one of these up how do you like it? have you had any problems with yours?