From a salesperson's perspective, most of the information about a car object is fixed, that is, the information is based on a real-world object and cannot be changed unless something changes about the real-world object. For example, it would not make sense to permit a salesperson to change the color of a car object to correspond to the color of the actual car he is trying to sell. Because a salesperson can change little about a car object, the car object has only a few action choices: