1. A method for managing XML data in a database system, comprising the steps of a database server receiving a XML schema; wherein said XML schema includes: a certain declaration of a XML date-time type, and a certain annotation associated with said certain declaration, said certain annotation specifying an aspect of a database representation of said XML date-time type; based on the XML schema, said database server determining a database representation for storing, within said database system, documents that conform to an XML schema; wherein said database server determining a database representation includes said database server determining, based on the certain annotation, a certain database representation for said declaration of said XML date-time type; and said database server generating mapping data that indicates correlations between said declaration of the XML date-time and said certain database representation.