Discretionary access controls can extend beyond limiting which subjects can gain what type of access to which objects. Administrators can limit access to certain times of day or days of the week. Typically, the period during which access would be permitted is 9 a.m. to 5 p.m. monday through friday. Such a limitation is designed to ensure that access takes place only when supervisory personnel are present, to discourage unauthorized use of data. Further, subjects rights to access might be suspended when they are on vacation or leave of absence. When subjects leave an organization altogether, their rights must be terminated rather than merely suspended. Under this type of control, the owner determines who has access and what privilege they have.
If the end users of resources had control of who had access and what privileges they have, they would be able to access any resource, because theyd have the ability to change access controls at will. If only the administrators controlled access to resources, it would be a major job duty (as well as a bureaucratic bottleneck for users) that would take time away from other administrative activities.