Database Maintenance Release Number
The second digit represents a maintenance release level. Some new features may also be included.
Application Server Release Number
The third digit reflects the release level of the Oracle Application Server (OracleAS).
Component-Specific Release Number
The fourth digit identifies a release level specific to a component. Different components can have different numbers in this position depending upon, for example, component patch sets or interim releases.
Platform-Specific Release Number
The fifth digit identifies a platform-specific release. Usually this is a patch set. When different platforms require the equivalent patch set, this digit will be the same across the affected platforms.