"This situation is exacerbated by the fact that these systems (especially the more limited ones), often don't provide some of the capabilities that users need. When this happens, users get creative and the intended semantics of the notation is easily cast aside for an operational semantics determined by what the algorithms do (to the extent that they can be understood). In many cases, users have creatively used these systems to achieve behaviour that was not intended by the designers."
W.A.Woods, J.G.Schmolze The KL-ONE Family
Computer and Mathematics with Applications, 23(2--5), pp 133--177. 1992.