Clicking a node sets the
Subject Object (S /O )
Try readR
Try writeW
Simple security propertyno read up
Read only if the subject dominates the object.
*-propertyno write down
Write only if the object dominates the subject.
Strong *-property: the subject may write only at its own exact label
Reference monitor log
Waiting for an access request…
Clicking a node sets label
A B
Join — least upper bound
The lowest label that dominates both. A subject needs at least this clearance to read A and B.
Meet — greatest lower bound
The highest label both A and B dominate. Anything at this label is readable by subjects at A and at B.
Every pair of the 16 labels has exactly one join and one meet. That property is what makes this partial order a lattice . Its top, (TS, {Army, Navy}), is system high; its bottom, (U, { }), is system low.