From previous page:
We simply ask for traders to be permissioned, primarily to protect traders from themselves (trading GOOG for example). We give most people enough room to trade most stocks. Our feeling is that we get a lot of slippage in the higher priced stocks, that's all.
We had a lot of traders ask for "permission" - most received it. You have to keep in mind that we have a lot of new traders still learning, and that's who we try to protect. FWIW, they are trading in very small lots anyway as they are honing their skills.
For most it was not even an issue.
Don