Efficiently Locating Schema Incompatibilities in an Extensible Markup Language

The work presented here extends an existing algorithm for testing if an inclusion relation exists between two markup schemata, to only take into account the parts of the grammar that have been used in a given subset of its language. Statistics for this purpose are gathered in combination with validation when documents are entered and are stored along with them in the repository. This modified subtyping relation is used to determine compatibility with the current database when a schema is upgraded.