In the context of Interfaces, they function as an internal extract, transform, load (ETL) mechanism.
They are often used by libraries, archives, museums, and other cultural institutions to translate data to or from MARC standards, Dublin Core, Text Encoding Initiative (TEI), and other metadata schemes.
Suppose the archive makes a digital copy of that manuscript and wants to display it on the web along with the information from the catalog.
In that case, it will have to translate the data from the MARC catalog record into a different format, such as Metadata Object Description Schema, that is viewable on a webpage.
It is essential to focus on the important goals and be willing to compromise to reach a practical conclusion to projects.