ISO 18611-2:2014规定了测定ISO 18611-1中规定的NOx还原剂AUS 40（尿素水溶液）质量特性所需的试验方法。在ISO 18611的其余部分中，术语“NOx还原剂AUS 40”将缩写为“AUS 40”。 本国际标准涵盖了适用于船舶应用的AUS 40的质量要求和指南，与制造方法或技术无关。

ISO 18611-2:2014 specifies test methods required for the determination of the quality characteristics of the NOx reduction agent AUS 40 (aqueous urea solution) specified in ISO 18611-1. In the remaining parts of ISO 18611, the term "NOx reduction agent AUS 40" will be abbreviated to "AUS 40". This International Standard is covering quality requirements and guidelines for AUS 40 for marine applications, irrespective of manufacturing method or technique.