Keys in XML

In this article a new type of key constraint in XML, called an XKey, is proposed. The motivation for an XKey is based on the observation that existing approaches do not always capture the fundamental properties of a key, namely identification and uniqueness, and it is shown that an XKey always has these properties. It is also shown that an XKey has the desirable property of extending the notion of a relational key. Keywords: XML, Integrity Constraints, Keys.