U.S. businesses can change dramatically over a span of 10 to 20 years. Look at a photo of a McDonald's restaurant or a Holiday Inn from 1978, and you might not recognize it.
Franchisors must allow for market changes over time, and they do so by incorporating a changing set of policies, standards and procedures in a confidential set of documents usually called "operating manuals." These manuals, which are separate from the franchise agreement, are typically updated as changes in the system occur or new policies are adopted. Franchise agreements themselves are also written to accommodate future changes, while assuring franchisees that the basic rights of the contract remain the same.