An approach to ambiguity analysis in safety-related standards

Standards for systems and software lifecycle processes have become rather popular in the last decade. Being expressed in natural language, their requirements, or clauses, are exposed to the risk of ambiguity, vagueness and subjectivity, even when safety of people and environment is the Standard's main concern. The paper addresses some issues of this problem and presents an experimental approach to the determination and evaluation of a set of properties of the clauses, which capture the notion of the quality of their expressions. The approach adopts a rather intuitive quality model for the English language and includes the use of a tool for sentence processing. Results of a descriptive analysis of some well-known, safety-related Standards for different software application domains are shown and discussed.