Ann Wrightson alphaXML Ltd ABSTRACT This paper presents an abstract model for meaningful communication between parts of a distributed system using structured documents. It is a first step towards a semantics of SGML/XML mediated inter-system communication based on situation semantics and the logic of information flow. After presenting the main account, with respect to simple XML documents, and to queries on topic maps, two directions are outlined for further work. One of these is user-centred, relating structure to user experience by means of the concept of genre. The other extends this initial work into a fuller formal model.