International discussions on the overarching topic of how to define and quantify what a "safe enough" Automated Driving System (ADS) is are currently hinged on the question of determining the relationship between "positive risk balance" (PRB) and "absence of unreasonable risk" (AUR). In order to advance the conversation on these important safety topics at the international level, it is first important to start from a shared common understanding, grounded in clear definitions and terminology. To that end, this paper will start with an overview of the notions of PRB and AUR; it will then summarize different positions of the present debate; finally, it will conclude that two possible interpretations exist for PRB, and that failure to distinguish them can lead to misunderstanding different parties' positions. The argumentation in this paper is aimed at showing that the two interpretations for PRB can actually complement each other, but can be considered independently, and can both be subsumed within non-prescriptive guidelines toward ADS safety assurance.

翻译：关于如何界定和量化“足够安全”自动驾驶系统(ADS)这一首要议题的国际讨论目前取决于确定“积极风险平衡”和“无不合理风险”之间的关系问题,为了在国际一级推动关于这些重要安全议题的对话,首先必须从基于明确定义和术语的共同理解开始,为此,本文件将首先概述PRB和AUR的概念;然后总结目前辩论的不同立场;最后,它将得出结论,对PRB存在两种可能的解释,不加以区分可能导致误解不同缔约方的立场;本文件的论据旨在表明,PRB的两种解释实际上可以相互补充,但可以独立地考虑,并且可以同时纳入针对ADS安全保障的非规范性准则。