The heart of an experts systems is the powerful corups of knowledge that accumulates during system building. The knowledge is explicit and organized to simplify decisions making. The importance of this feature of experts systems cannot be overemphasized.
The accumulation and codification of knowledge is one of the most important aspects of a an experts systems.
This has implications that go beyond the mere construction of a program to perform some class of tasks. This is because the knowledge that fuels the experts system is explicit and accessible unlike most conventional programs.