Cooperative work is of long-duration, follows certain workflows, and presupposes information exchange among participants. Conversely, traditional database systems manage data essentially by isolation of transactions and by the assumption that each transaction maintains the consistency of the database. To overcome this gap, this paper proposes a multiversion data model, which both records revisions of data and manages the consistency of the data based on the semantics of workflows. Following this, a transaction consistency management mechanism is introduced to manage the consistency of transaction's retrieval result, satisfying the both requirements of using the latest consistent versions and avoiding rollback of a whole transaction.