The Sun Network Software Environment (NSE) is a network-based object manager for software development.The NSE supports parallel development through an optimistic concurrency control mechanism, in which developers do not acquire locks before modifying objects.Instead, developers copy objects, modify the copies, and merge the modified objects with the originals.Objects managed by the NSE are typed, and the set of types can be extended by tool builders.The NSE is designed to work with heterogeneous implementations and poor communication.

We present an algorithn for the determination of run-time types which functions in the presence of errors, and show that it provides more information than that obtained using a previously published algorithm.In Section 1 we define the problem and state the requirements for a practically useful type prediction algorithm. In Section 2 we introduce a model programing language and in Section 3 define type inference rules for that language. Section 4 presents a type prediction algorithm and Section 5 describes how to apply the results to solve the problems stated in Section 1. Section 6 presents an example of our procedure and demonstrates how previous work does not satisfy all requirements.