412 ◾ Appendix D
General release-based constraints:
R(Al, A2,... An) AND Release(Ai, Unclassified)— > Level(Aj) =
Secret
(e attribute Aj of relation R is Secret if the attribute Ai has been released at the
Unclassified level)
Example: SHIP(S#, SNAME, CAPTAIN, M#) AND Release(SNAME,
Unclassified)— >
Level(CAPTAIN) = Secret.
Individual release-based constraints:
R(Al, A2,... An) AND Individual-Release(Ai, Unclassified)— >
Level(Aj) = Secret.
e individual release-based constraints classify elements of an attribute at a particular
level after the corresponding elements of another attribute have been released. ey are
more difficult to implement than the general release-based constraints. In our design,
the individual release-based constraints are hand ...