Figure 26.5 shows the contents of the lookup table, sometimes called the Resident
Object Table (ROT), after four objects have been read from secondary storage. If we now
wish to access the Staff object with object identity OID5 from the Branch object OID1, a
lookup of the ROT would indicate that the object was not in main memory and we would
need to read the object from secondary storage and enter its memory address in the ROT
table. On the other hand, if we try to access the Staff object with object identity OID4 from
the Branch object, a lookup of the ROT would indicate that the object was already in main
memory and provide its memory address.