Evergreen’s OpenSearch service can return search results in many formats, including HTML, MARCXML, and MODS. As of version 2.4, it can also return results in binary MARC21 format.
When making an HTTP request to an Evergreen system using the OpenSearch API, you must include the term "marc21" in the appropriate location within the URL to retrieve a feed of MARC21 records in a binary format. The following example demonstrates the appropriate form of the URL:
You can add this term manually to the URL produced by a catalog search, or you can create a script that would retrieve this information automatically.