Minor There is value in stating that EMIX and WS-Calendar can be leveraged in EI to address the areas where price and schedules apply. However, as introductory paragraph for messages and services this fails to speak of the broader range of scope of EI, which includer additional drivers other than price. Language should be adjusted accordingly to specify that EMIX and WS-Calendar have a function within EI, and not that EI is dependent on EMIX and WS-Calendar to solve all interoperation issues.