A formal model for an expressive fragment of XSLT

Abstract

The extension of the eXtensible Style sheet Language (XSL) by variables and passing of data values between template rules has generated a powerful XML query language: eXtensible Style sheet Language Transformations (XSLT). An informal introduction to XSTL is given, on the bases of which a formal model of a fragment of XSLT is defined. This formal model is in the spirit of tree transducers, and its semantics is defined by rewrite relations. It is shown that the expressive power of the fragment is already beyond that of most other XML query languages. Finally, important properties such as termination and closure under composition are considered.