UDC Master Reference File (MRF)

What is the UDC MRF?

The UDC Master Reference File (MRF) is the definitive, authorized version of the UDC. The UDC MRF database contains the UDC schedules together with records needed for administration, maintenance, archiving, UDC edition production and distribution. English is the main language of the database.

How often is the MRF updated?

Since 1992, the UDC MRF has been updated and new versions of corrected and extended UDC schedules distributed to publishers and users annually. Proposals and announcements for change to the UDC schedules are published annually in Extensions and Corrections to the UDC together with the latest approved changes. The latest UDC MRF release in 2011 contains over 70,000 UDC classes.

How can I obtain UDC MRF?

The UDC MRF exports are available to publishers and users under licence.

MRF Exports

The UDC MRF is distributed in English to licensees for publication or use as a set of database exports. UDC MRF is stored in a relational database (mySQL). Previously, from 1992-2008 UDC was maintained in a CDS/ISIS database. We continue to provide exports for CDS/ISIS, and we provide text exports supporting the following character coding tables: UTF8 and CP850.

There are 3 types of standard UDC MRF exports distributed with the UDC MRF release, supporting different type of users:

  • exports for publishing in print form (a simple tagged text export)
  • exports for the CDS/ISIS database (ISO2709)
  • platform-independent exports suitable for use by software:
    • extended tagged text export
    • XML export

A simplified data element schema is available as a document (pdf). Other types of exports are provided to licensees on demand.