A reasonable accommodation is an adjustment made in a system to accommodate or make fair the same system for an individual based on a proven need. That need can vary. Accommodations can be religious, physical, mental or emotional, academic, or employment-related, and law often mandates them. Each country has its own system of reasonable accommodations. The United Nations use this term in the Convention on the Rights of Persons with Disabilities, saying refusal to make accommodation results in discrimination. It defines a "reasonable accommodation" as: necessary and appropriate modification and adjustments not imposing a disproportionate or undue burden, where needed in a particular case, to ensure to persons with disabilities the enjoyment or exercise on an equal basis with others of all human rights and fundamental freedoms; Employers and managers are often concerned about the potential cost associated with providing accommodations to employees with disabilities. However, many accommodations, such as moving an employee to a different desk or changing the work schedule, do not have any direct cash costs (56% in a survey of employers conducted by JAN), and most others have only one-time costs (e.g., to buy a different style of computer mouse). Accommodation costs may be offset by the savings associated with employing people with disabilities (higher performance, lower turnover costs). Rarely, two people will need accommodations that conflict with each other. Creative problem solving may be required to find ways to accommodate both people. For example, the United States Department of Justice recommends that if a program serves a person with a service dog and a person who is allergic to dogs, that the program separate them physically, by asking them to stay in different rooms or on opposite sides of the same room. In some cases, the accommodations that are practical may not be the first choice for all participants.