There are many examples of actions on abstract data types which can be correctly implemented whit nonserializable and nonrecoverable schedules of reads and writes we examine a model of multiple players of abstraction that explains this phenomenon and suggests an approach to building layered systems with transaction oriented synchronization and roll back our model may make it easier to provide the high data integrity of reliable database transaction processing in a broader class of information systems we concentrate on the recovery aspects here; a technical report [Moss et al. 85] has a more complete discussion of concurrency control.