Draft Network Codes ACER Opinion 02-2015 on the Network Code on Harmonised Transmission Tariff Structures for Gas ACER Opinion 14-2014 on the Network Code on High Voltage Direct Current Connections and DC-Connected Power Park Modules ACER Opinion 04-2014 on the ENTSOG Cost-Benefit Analysis Methodology ACER Opinion 21-2013 on the Network Code on Interoperability and Data Exchange Rules ACER Opinion 12-2013 on the Network Code on Operational Planning and Scheduling (OPS) ACER Opinion 10-2013 on the Network Code on Operational Security ACER Opinion 06-2013 on the Network Code on Demand Connection ACER Opinion 01-2013 on the Network Code on Gas Balancing of Transmission Networks ACER Opinion 10-2012 on ENTSO-E's Network Code on Capacity Allocation and Congestion Management ACER Opinion 04-2012 on the Network Code on CAM for European Gas Transmission Network ACER Opinion 04-2012 Reasoning on the Network Code on Capacity Allocation Mechanisms for the European gas transmission network ACER Reasoned Opinion 04-2012 Consultants Study - Final Report