So, on other exchanges all you need is "your handle" aka steemit user name. Which makes it easy, token transactions can only occur on the STEEM block-chain over the STEEM network. For instance on poloniex, after you click on the withdraw button, a box comes up with an address line and an amount line. If you put my user name ... tintop ... in the address line and 10.00000000 in the amount line, then confirmed the withdraw. I would receive 9.???????? in my steemit wallet. The reason it is under 10.0 STEEM is the transaction fee. The network fee on poloniex is 0.01000000 STEEM but may be different in the future and on other exchanges.