Final answer:
In lattice-based access control, a subject is an entity like a user or a process that is assigned a level within a lattice defining its access rights to resources.
Step-by-step explanation:
In a lattice-based access control, a restriction table is indeed associated with a particular subject, such as a user. A subject in this context refers to an entity that can request access to a resource, such as a user or process. Lattice-based access control structures permissions and rights in a lattice formation, where each point in the lattice represents a unique combination of information and resource access levels. Subjects are assigned a particular level within this lattice that defines the actions they can perform or the resources they can access. Lattice-based access control is commonly used in environments that require fine-grained security control, such as government or military systems.