As collaboration support for multiple users to work on the same Office documents becomes more and more desirable, some work has been done to provide real-time collaboration support for Microsoft Office. These systems use tightly coupled concurrency control mechanisms, which directly determine their collaboration support capabilities as well as implementation complexities. In this project, we choose StarOffice as the platform to drive our research on collaboration support for Office systems, where a flexible concurrency control framework is proposed. In this framework, concurrency control mechanisms are decoupled from the rest of system in such a way that multiple concurrency control mechanisms are offered for users to choose from according to their specific collaboration situations, and that new concurrency control mechanisms can be easily added to the system without touching the code of existing concurrency control mechanisms.