Diagnostic criteria for ARDS have changed over time as understanding of the pathophysiology has evolved. The international consensus criteria for ARDS were most recently updated in 2012 and are known as the "Berlin definition".[13][14] In addition to generally broadening the diagnostic thresholds, other notable changes from the prior 1994 consensus criteria[3] include discouraging the term "acute lung injury," and defining grades of ARDS severity according to degree of decrease in the oxygen content of the blood.[citation needed]