When you install a software product release, files from previous versions of the release are automatically removed before the new files are installed (the exception is configuration files, which are saved if they contain local modifications). If a product release includes hardware-specific files, the installation utility automatically determines the file version that is needed on a particular model and installs that version.
Product releases may have prerequisites that require a particular installation order. They might also have compatibility requirements with other installed products. Inst protects users against potential problems by preventing installation if there are any unresolved incompatibilities or prerequisites (unless you override this safeguard).
Installation instructions, including prerequisites and incompatibilities information, are provided in the product release notes, which are always included as an installable subsystem of the product. You can read product release notes from the distribution CD using the CDgrelnotes or CDrelnotes command. Instructions for reading release notes are included in the CD jewel case insert.
Figure 1-1 illustrates the hierarchical structure of a software distribution that comprises three software product releases.
Figure 1-1 : Components of a Distribution