Knowledge base maintenance is managed by constructing a formal model. In this model the representation of each chunk of know- ledge encapsulates the knowledge in a set of declarative rules, each of which in turn encapsulates the knowledge in a set of imperative programs. In this model an “item” is the unit of knowledge representation. Items are at a higher level of abstraction than rules. Understanding what has to be done to maintain the integrity of an item leads to a specification of the modifications to the set of programs that implement it. An analysis of the maintenance of the formal model is achieved by introducing maintenance links. Analysis of the maintenance links shows that they are of four different types. The density of the maintenance links is reduced by transforming that set into an equivalent set. In this way the knowledge base maintenance problem is analysed and simplified. A side benefit of knowledge items as a formalism is that they contain knowledge constraints that protect the knowledge from unforeseen modification.