Through the use of different stylesheets it is possible to transform the information contained in XML documents and present it in different ways, for example to create personalised presentations. However, in doing so there is a danger that the transformation may result in a presentation, which fails to carry the essential message intended by the provider of the source document. We believe that the Information Provider should be able to provide constraints on permitted transformations of their document, stating for example which elements are mandatory, which must not be changed, which must have the order preserved. This paper discusses the need for such transformation constraints, and proposes a simple metadata annotation expressing the required constraints. We consider the adequacy of the proposed approach, and alternative ways to constrain transformations. © Springer-Verlag 2004.