To be productive, cooperative work has to be supported efficiently so that users do achieve their goals. This requires solving the wellknown fundamental problem of replicas consistency. Update-based solutions are easy to use transparently with commercial applications, but consider every modification in a document as a new document update, thus fostering conflicts and hindering concurrency. Operational-based solutions promise increased concurrency, by interleaving compatible modifications from

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... fferent users. They require central reconciliation algorithms, and cannot be applied to commercial applications without further instrumentation. We propose the notion of a semantic chunk, i.e., a semanticallyannotated document region with application relevance, that is promoted to a full-right entity w.r.t. consistency information and enforcement. This unit, being smaller than a file and semantically richer, allows greater concurrency and better update merging with less aborts than current solutions.