A Probably Heretical Look at Some of the Problems with the Conceptual Basis for Low Level and Derived Requirements, Followed by a Ray of Hope

Abstract

Despite years of discussion within several RTCA/EUROCAE committees and the publication of various FAQ,s., both numerous unofficial ones on the web and the official ones published in DO-248C [4], there is still a fair bit of confusion over exactly what constitutes low level requirements and derived requirements. The problem is exacerbated by the fact that, although the terms are intuitively straight forward and appealing, the DO-178C [3] definitions are at odds with those in several other well-known standards documents such as IEC/ISO/IEEE 24765, Systems and Software Engineering - Vocabulary [2]. The result is that when trying to settle the seemingly interminable disputations about the nature of these terms, so central to understanding several crucial DO-178C objectives., we have little to build on from any outside sources. The purpose of this paper is to show the extent of the problem and then propose some possibly heretical ideas for the eventual upgrade of DO-178C to a D version in these areas, ideas which have been further developed in the years since the overly hurried and ultimately unsuccessful efforts in IP-217 to address these issues during the course of SC205.