The Cisco Unified Communications system includes the following types of releases:
•Major release—Marks the beginning of a major new release version. This release type typically is based on a major release of at least one of these components: Cisco Unified Communications Manager, Cisco Unity, Cisco Unified MeetingPlace, or Cisco Customer Response Solutions.
•Minor release—Adds features and fixes to an existing major release. This release type can consist of revisions to existing components and new versions of components.
•Maintenance release—Contains bug fixes for one or more of the components. This release type is based on an existing major or minor release.
For example, in Cisco Unified Communications release 5.1(1), "5" indicates the major release, the first "1" indicates the minor release, and the second "1" indicates the maintenance release.