The Multi-version and Single-display Strategy in Undo Scheme

Consistency maintenance is one of the most significant challenges in groupware systems. In groupware systems, the effect of incorrect execution will be more extensive for it is done in distributed group editors, so the user will have more dependence on undo. While intention violation puzzle has never been addressed in any published work, it will destroy the consistency and lead to a crash. We propose a Mark & Retracing based method to reach the goal of consistency maintenance and achieve multi-version and single-display strategy in undo scheme. It is different from operation transformation method and provides a new perspective into group editors