Abstract
One of the key characteristics of XML applications is their dynamic nature. When a system grows and evolves, old user requirements change and/or new requirements accumulate.
Apart from changes in the interface, it is also necessary to modify the existing documents with each new version, so they are valid against the new speci cation. The approach presented in this paper extends an existing XML conceptual model with the support for multiple versions of the model.
Thanks to this extension, it is possible to de fine a set of changes between two versions of a schema. This work contains an outline of an algorithm that compares two versions of a schema and produces a revalidation script in XSL.