A mapping schema and interface for XML stores. Sihem Amer-Yahia and Divesh Srivastava. Most XML storage efforts have focused on mapping documents to relational databases. Mapping choices range from storing documents verbatim to shredding documents into relations in various ways. These choices are usually hard-coded into each storage system which makes sharing loading and querying utilities and exchanging information between different XML storage systems hard. To address these issues, we designed MXM and IMXM, a mapping schema and an interface API to define and query XML-to-relational mappings. A mapping is expressed as an instance of MXM. MXM is declarative, concise and captures most existing XML-to-relational mappings. Mappings can be expressed for documents for which no schema information is provided or documents that conform to either a DTD or an XML Schema. IMXM is an interface that allows querying of information contained in a MXM mapping. IMXM is designed as a library of functions which makes it easy to use inside any utility or application that needs to gain access to the XML-to-relational mapping. MXM is extensible and can incorporate new XML-to-relational mappings. We implemented a prototype that allows to define a mapping as an instance of MXM and uses it to generate a repository of meta information on the XML data, the relational data and the mapping choices. We implemented IMXM on top of this repository and used it for generating a relational schema and loading XML documents into the corresponding relational database.