The CSA have published proposed amendments to National Instrument 21-101 Marketplace Operation (NI 21-101) and National Instrument 23-101 Trading Rules (NI 23-101) (the ATS Rules) (and their related companion policies) for comment and review. The proposed amendments include proposals for a framework to implement trade-through protection that will require all visible, immediately accessible, better-priced limit orders to be filled before other limit orders at inferior prices, regardless of the marketplace where the order is entered. Other amendments relate to clock synchronization, technology requirements for marketplaces, information processor requirements, and best execution reporting requirements.These proposed amendments on trade-trough protection have been developed further to the discussion paper published by the CSA on July 22, 2005, entitled CSA Discussion Paper 23-403 Market Structure Developments and Trade-through Obligations and the Joint Notice on Trade-Through, Best Execution and Access to Marketplaces published by the CSA in conjunction with RS (now IIROC) on April 20, 2007. Comments on these proposed amendments will be accepted until January 15, 2009.