A Formal parameter is a Field that is needed to determine exactly which data set should be retrieved from the database. The definition of the formal parameters is stored in the Entry definition or function definition in the DID. Formal parameters have the same attributes as a field and in most instances, each formal parameter is also included as a Field of that Entry. In most cases, you do not have to worry about the formal parameters during Model development. If the Entry is a Main Entry, the actual parameters will be provided through Key Selection. If the Entry is a Subentry, the actual parameters are defined in the Entry-Subentry definition. Actual parameters can also be provided or overridden in an Entry application.