For many stored procedures, you provide a value and receive a value in return. These values are known as input and output parameters. For example, a sales tax calculation stored procedure can take a single input parameter, such as the price of an item. After performing the calculation, the stored procedure returns two output parameters, the amount of tax, and the total cost of the item including the tax.
The Stored Procedure transformation sends and receives input and output parameters using ports, variables, or by entering a value in an expression, such as 10 or SALES.