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.