On listed stocks on the L2s NYSE usually showing along with CSE, BSE, ASE. I assume this is Cincinnati, American, Boston exchanges, etc.. Also, NAS (Nasdaq?). For example: CSE 5.03 ASE 5.06 NAS 5.03 CIN 5.08 NYS 5.00 NYS 5.10 Using IB (Best Ex), they seem to route to NYS, in fact doesn't even reflect the other quotes on its Level 1. AB Watley told me that you cannot preference CSE for example to sell, they route using ISI I think. Any order entry systems that allow this? Would a route to ISI go to the exchange with the Best Bid/Offer?