A method for allowing client computers in a distributed object-based data storage system to interpret higher revision data structures. In one embodiment, clients request layout maps of objects to be accessed from respective storage managers in the system and then construct and execute directed acyclic graphs (DAG) to accomplish desired I/O operations for data access. When a client computer running an older software revision is not able to interpret a particular data organization supplied by the storage manager that was designed after that client's software was installed, the client sends to the storage manager a description of the desired data access operation. The storage manager, in turn, interprets a data layout scheme for a client on a per-access basis and returns to that client a DAG containing a data structure that describes the sequence of I/O operations necessary to effect the data access. The client can then execute the storage manager-supplied DAG to carry out the data access.