About expressions BIRT Studio supports typical mathematical operations, such as addition, subtraction, multiplication, and division. Computed columns, however, are not limited to mathematical calculations. BIRT Studio also supports many functions for manipulating date-and-time and string data. A function is a set of instructions that do something and return a result. For example, if a customer name field contains values with leading or trailing blank characters, you can remove the blank characters by using the TRIM( ) function as follows: TRIM([CustomerName]) In this example, [CustomerName] is the input value, or argument, you supply to the TRIM( ) function to tell the function to trim the values in the CustomerName field. More examples of expressions used in computed columns appear later. For descriptions of the supported functions, see Functions and operators.