Object Identifiers (OIDS):

Oracle8's object identifiers (OIDs) are essentially the reincarnation of the pointer construct. ROWIDs are used through conventional tables and can modify during the life span of that table. OIDs are used only through object tables and they do not modify or repeat.

An OID is a 128-byte base-64 number generated internally through the Oracle engine. The OIDs are never reused once they are discarded. The Oracle guarentees that OIDs are globally unique, even across a distributed system. The OIDs are created implicitly whenever an object table is created.