Software that requires values expressed at runtime. A parameter-driven program solves a problem that is partially or entirely described by the values (parameters) entered on the command line when the program is called for. For example, typing bio 6-20-36 might load a program called "bio" that calculates biorhythms for someone born on June 20, 1936. In this case, the date is a required parameter. The more user-friendly approach is a menu-driven program that would have you select a menu option and present you with a data entry box to type in date of birth. When One Program Calls Another Parameter-driven software is widely used when a program is called for and loaded by another program rather than by the user. Since the parameters are generated by one program and used by another, any number of parameters can be passed no matter how obscure the codes.