The Extensible Markup Language is susceptible to security breaches because it does not incorporate methods to protect the information it encodes. Our work presented in this paper focuses on the development of a formal language which can provide role-based access control to information stored in XML formatted documents. Our language has the capacity to reason whether access to an XML document should be allowed. The language, Axml(T ) , allows for the specification of authorisations on XML documents and distinguishes itself from other research with the inclusion of temporal interval reasoning and the XPath query language.