TBE buffer-what is the role of each component? - (Oct/09/2012 )

I wonder what is the role of Tris, boric acid and EDTA in the electrophoresis buffer?
I've read in wiki which says that tris acid keeps DNA deprotonated and soluble in water while EDTA is chelator for divalent cations. Its there any reference?
Thank you!

tris and borate are buffer salts with different pK. using them together extends the buffering range. they are also the leading and trailing ions during electrophoresis (although, since the method is a continuous buffer system this doesn't matter as much as in a discontinuous system). however, the buffer acts as an electrolyte to carry current through the gel, providing the motive force. water wouldn't work so well.