Michel Biezunski Steven R. Newcomb Specializing Occurrences in Topic Maps by Association Template Subclassing. 2001 conf/extreme/2001 Extreme Markup Languages® http://www.mulberrytech.com/Extreme/Proceedings/html/2001/Biezunski01/EML2001Biezunski01.html db/conf/extreme/extreme2001.html#BiezunskiN01