We describe an initiative under way at Warwick to provide a technical foundation for computer aided learning and computer-assisted assessment tools, which allows a rich dialogue sensitive to individual students' response patterns. The system distinguishes between dialogues for individual problems and the linking of problems. This enables a subject specialist to craft individual questions and units of learning material, while allowing the order of presentation of the units to depend on a student's interaction history. We develop a markup language, specified as an XML DTD, to enable the storage of data for use in such systems. A full XML markup for the example problem is appended. (Contains 3 tables and 3 figures.)