Dewan, PrasunSharma, Anshu2017-04-152017-04-151999978-0-306-47316-6Currently, collaborative systems manipulating the same artifact but implementing different policies and architectures cannot interoperate or "collaborate" with each other. Therefore, it is not possible for users to use different collaborative systems to work on a single shared artifact. As an initial step towards such interoperation, we have carried out an experiment involving the interoperation of two heterogeneous collaborative spreadsheets. The experiment has resulted in some general protocols, techniques, and lessons applicable to the interoperation of systems offering different concurrency-control - policies, couplings, and architectures. The paper surveys different approaches along these three dimensions, motivates the rationale for inter-operating them, identifies issues m their interoperation, and presents and evaluates solutions for a small number of interoperation scenarios in the surveyed design space.enText10.1007/0-306-47316-X_20