ZapNote: eXcelon
There are two major categories of XML data store: extensions to relational database systems (RDBMS) and a new category of "Native" XML data stores (NXDs). While extensions to RDBMS systems simply enable RDBMS databases to map XML documents to relational tables, NXDs allow users to insert XML documents directly into the system without need for mapping or interacting with anything besides the XML document. eXcelon’s eXtensible Information Server (XIS) is an "XML data management system (XDBMS)" that is aimed squarely at the problem of storing arbitrarily structured XML documents. Among other features, XIS provides node level management of XML data, dealing with XML document information at the element level, rather than the document level.