What does the II and the ( and the ) mean in the expression on measures list of Operators? Please provide examples and definition

What does the II and the ( and the ) mean in the expression on measures list of Operators? Please provide examples and definition

II indicates the 'OR' operator which is used to take care of otherwise expressions. E.g. Unit Sales == 500 II Unit Sales !=1000 (Unit Sales equals 500 or not equal to 1000). ( ) indicates opening and closing braces generally used to specify multiple conditions. E.g. Average Inventory Cost Expression: (SUM(C318) + SUM(CASE WHEN DATE_KEY = #startenddatekey# THEN C175 ELSE 0 END)) / (#monthdiff# + 1)