Basic requirements for proven-in-use arguments

Proven-in-use arguments are needed when pre-developed products with an in-service history are to be used in different environments than those they were originally developed for. A product may include software modules or may be stand-alone integrated hardware and software modules.The topic itself is not new, but most recent approaches have been based on elementary probability such as urn models which lead to very restrictive requirements for the system or software to which it has been applied. The aim of this paper is to base the argumentation on a general probabilistic model based on Grigelionis or Palm Khintchine theorems, so that the results can be applied to a very general class of products without unnecessary limitations. The advantage of such an approach is also that the same requirements hold for a broad class of products.