actually, the postative should be the round side because when you are dealing with the electromagnetic fields generated by the current traveling through the wire, a dielectric that is asymetrical will not shield the transmission line as well as one that is symetrical. thereore induced noise via an electrostatic or electromagnetic field will be way more apparent because of the dielectric that is used to insualte the transmission line will be constant down the entire run of the signal cable.
in lamens terms. square = - round = +
lawl im just playin, i had to do the same thing as guy above but better to piss that second guy off again. just label the crap and you dont have to worry about it haha.