A persistent C++ variant GNU E is a persistent, object oriented programming language developed as part of the Exodus project. GNU E extends C++ with the notion of persistent data, program level data objects that can be transparently used across multiple executions of a program, or multiple programs, without explicit input and output operations. GNU E's form of persistence is based on extensions to the C++ type system to distinguish potentially persistent data objects from objects that are always memory resident. An object is made persistent either by its declaration (via a new "persistent" storage class qualifier) or by its method of allocation (via persistent dynamic allocation using a special overloading of the new operator). The underlying object storage system is the Exodus storage manager, which provides concurrency control and recovery in addition to storage for persistent data.