Package Upgrade is the replacement of a package with its newer version to enhance functionalities or fix software defects.
Package upgrades are based on the following two scenarios:
Packages that
are installed on the data drive or the RAM drive can
be upgraded directly by installing a SIS file of type SA, SP or PU.
Packages that are installed on the ROM drive can be upgraded only by means of eclipsing. For details on how to upgrade package files on ROM, see Upgrading OS Components.
Orphan files that are not installed by an installation package
can be overwritten only if the device creator has enabled the corresponding
option (AllowOrphanedOverwrite) in the installation
policy file.