The Math Working Group has published a W3C Recommendation of  “XML Entity Definitions for Characters.” Notation and symbols have proved important for human communication, especially in scientific documents. Mathematics has grown in part because its notation continually changes toward being succinct and suggestive. On the Web, the majority of cases it is preferable to store characters directly as Unicode character data or as XML numeric character references. This document is the result of years of employing entity names on the Web. It presents a completed listing harmonizing the known uses of character entity names throughout the XML world and Unicode. Learn more about the Math Activity. http://www.w3.org