Martin J. D&#252;rst. <a href="http://www.w3.org/TR/1998/WD-charreq-19980710"><cite>Requirements for String Identity Matching and String Indexing.</cite></a> 10 July 1998. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/1998/WD-charreq-19980710">http://www.w3.org/TR/1998/WD-charreq-19980710</a>