n.the practice of converting an electronic file to a different standard file type to circumvent obsolescenceCaplan 2007, 307Format migration is the process of creating a version of a file in a more current format, particularly if the format of the source file is in danger of becoming obsolete.Caminita, Cook, and Paster 2017, 296Format migration for digital files is an ongoing preservation requirement for the medium, with formats, and the programs required to read them quickly, becoming outdated and obsolete.Prentice and Gaustad 2017, 15Depending on the original file format however, it may be desirable to transcode to a new target format rather than simply copy from the original file (see sections 10 & 11). This process is known as format migration.Fleischhauer and Bradley 2019, A-4, fn. 5In the field of digital preservation, the term migration is used in two ways. Media or system migration refers to the movement of digital files from obsolete data-storage media or an obsolete data-management system to new media or a new system. Media migration is sometimes called physical migration and media refreshment. In this form of migration “the bits do not change.” In contrast, format migration, also known as logical migration, refers the movement of a content item from one format to another: “the bits do change.”Pendergrass et al. 2019, 189While format obsolescence is a real risk to digital content, practitioners should not be overly zealous with format migrations, particularly for files in formats not at high risk. Institutions should define local file format policies based on calculated risk assessments rather than relying on the default file format policies implemented in digital preservation software systems.
In format migration, the content is preserved but the bits are not. In past use, the term has been less precise and could have included media migration.