This paper presents SEdit, a formally designed and developed application for collaborative HTML group editing support. The design model separates coordination from cooperation and communication, allowing different cooperation interfaces (ASCII support and HTML support) to be integrated with the same coordination system. The coordination protocol allows different users to simultaneously work on different parts of the shared document. This protocol has been synthesized from a formal description based on graph grammars. (C) 2002 Elsevier Science Inc. All rights reserved.