Discretionary Access Control (DAC) is characterized by the ability of a resource owner to make decisions and assign access permissions to other users. In this scenario, individual users have the discretion to set permissions on their own files within the document management system. Role-Based Access Control (RBAC) assigns access based on roles within an organization, while Mandatory Access Control (MAC) is a more rigid model controlled by system-enforced policies, which is not contingent on user discretion.