The Replace Media function provides the capability to reproduce the AIPs over time. Within the Replace Media function the Content Information and Preservation Description Information (PDI) must not be altered. However, the data constituting the Packaging Information may be changed as long as it continues to perform the same function and there is a straight forward implementation that does not cause information loss. The migration strategy must select a storage medium, taking into consideration the expected and actual rates of errors encountered in various media types, their performance, and their costs of ownership. If media-dependent attributes (e.g., tape block sizes, CD-ROM volume information) have been included as part of the Content Information, a way must be found to preserve this information when migrating to higher capacity media with different storage architectures. Anticipating the terminology of section 5 [The Preservation Perspectives section of the OIAS document], this function may perform "Refreshment", "Replication", and "Repackaging " that is straightforward. An example of such "Repackaging" is migration to new media under a new operating system and file system, where the Content Information and PDI are independent of the file systems. However, complex "Repackaging" and all "Transformation" are performed under Administration supervision by the Archival Information Update function to ensure information preservation. Refer to section 5 for a detailed description of migration issues.