Abstract: Messages at nodes of a distributed data system are processed asynchronously. Each data atom shared by a pair of nodes is characterized by dipole halves maintained at each node including an access control characteristic, a quality control characteristic, and a pair of rank values. A rank value is a value which monotonically increases (with respect to time) with each significant event. A message from a paired node requesting a change to a dipole half at this node includes the set of rank values at the paired node for the shared data atom. This node compares the rank values which it maintains with those received from the paired node and, based upon the result, selectively rejects or processes the request.