The article discusses uniform transparent access to objects, be they local, remote, persistent, or mobile. In this way, the authors facilitate distributed programming and persistence management. An object (the target) is accessed through a reference. A reference retains its meaning as it is copied, stored, passed in messages, and as the target migrates. A reference is used to invoke a procedure (or method) of the target object. References support standard single-space targets, as well as fragmented objects. The cost of using a reference to a local object is comparable to the cost of accessing the object through a pointer. In the implementation, a reference is a chain of links. Each link embodies a small piece of functionality. A chain may be composed of an arbitrary number of links