From the author:
NetCLOS is "... an extension of Common Lisp which allows the definition of parallel programs within that functional and object-oriented language. In particular, the extensions are the introducing of active objects, sending synchronous and asynchronous messages between them, automatic and manual distribution of active objects to object spaces, and transparent object managing. With these extensions object-oriented parallel programming on a workstation cluster using different Common Lisp images is possible. These concepts are implemented as an extension of Allegro Common Lisp subsumed by the name NetCLOS."