Few authorities make clear precisely what they mean by the term 'knowledge'. This representation can be used to express rules, which are firm statements of defined relationships between variables. These relationships are based on causal models, and are generally true, or at least firmly believed to be generally true. In addition, the representation can be used to express heuristics, or 'rules of thumb', which may be used as a guide, and are usually true, but which sometimes may not be. They are based on correlation or intuition, rather than on causal models.
Heuristics represent 'surface knowledge' about the domain, whereas rules represent 'deep knowledge'.
Expressing knowledge as rules and heuristics has two particular advantages over previous software development technology. The other advantage is that knowledge that presently exists in the forms of rules can be captured in that form, without having to be first converted by teams of analysts and programmers into forests of data definitions and procedures. KBT therefore contains a an important discontinuity compared to conventional software development technology. The Process Beyond a mere definition of terms, management needs an explicit understanding of the process which KBT applications entail. Exhibit 1 provides a model of the development and use of KBT as it is conventionally practised.