Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Metabolic syndrome was defined according to the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian-Americans [30], which includes at least three of the following components: 1) waist circumferences $90 cm in men or $80 cm in women; 2) triglycerides $1.
Category: