Singleton

A singleton is an object-oriented programming term. The use of a singleton can maintain the premise that there is only one singleton object type at a site, in keeping with existing RFC protocols which do not have the notion of multiple instances of a type being at the same server. the singleton object type was created to support the use of these protocols; a single address space may have multiple instances of the same singleton type.

URLs:

ILU Reference Manual - ILU concepts

This manual at the Xerox Parc ftp site will probably give you more information than you really need about singletons and their function.

W3E References:

object oriented