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Master Reference File (MRF)
What is the MRF? | How can I access
it? | Maintenance | Distribution
and licence contracts | MRF Licence | MRF structure and content | Major
changes to the UDC since 1993 | Manual
What is the MRF?
The Master Reference File (MRF) is a database that contains the UDC schedules together with records needed for administration, maintenance and archiving. It contains the definitive, authorized version of the UDC and is maintained as a working tool for the UDC Consortium. The UDCC created and maintains the MRF database in order to manage the content of the UDC, to determine the need and priority for revisions, and to keep track of changes over time.
To safeguard its contents, a duplicate of the database is used for regular maintenance and updating during the year. Once finalized, this is used to create the new master file each year (during December/January). The new version of the MRF containing that year's changes is used to provide the output for distribution to Consortium Members and licence holders and, if their applications are approved, also to other users.
Proposals for change to the UDC schedules are published annually in "Extensions and corrections to the UDC" together with the latest approved changes. Copies of each annual edition of Extensions and corrections are printed during November and normally available for sale in December. All agreed cancellations are published on the UDCC web site.
The MRF is the definitive source on which publishers base their UDC publications or services. Users other than publishers can also benefit from direct access to the MRF, whether for classification, research or other purposes. They may need to support their specific use, in particular, by employing a suitable software application.
The MRF database was designed using UNESCO's CDS/ISIS software package that supports international standards for the bibliographical data exchange format (ISO 2709). CDS/ISIS is internationally-accepted information retrieval software, very popular because of its low cost (free of charge for non-profit institutions), stability and adaptability. Although it has no special requirements, when it comes to computer processing or memory it is capable of handling a large amount of data and has very robust retrieval and sorting facilities. Furthermore, it is available for different platforms (DOS, Windows, UNIX) and it is constantly improved and developed by both UNESCO and its international user community.
Data from the MRF database can be exported either in ISO-2709 format or as plain ASCII text and can be used in any other ISO-2709 compliant application or further formatted for printing, publishing or other end use. See more about MRF database design, structure and content.
For reasons of efficiency (in terms of cost and time) the size of the MRF is limited to approximately the size of the 'Medium editions', as they were known until the early 1990s.
At that time the core of c. 60,000 class numbers was chosen as a manageable but representative selection of recorded information and knowledge: it is now some 66,000 numbers (2005). As the working language of the Consortium is English, when the MRF was first created (during 1992-93), the main source (70%) for its content was the International Medium Edition: English text published by the British Standards Institution in 1985 (it was already available in machine-readable form). The remaining 30% was derived from subsequent Extensions and corrections to the UDC and recently published editions in other languages, as well as some necessary expansions in hierarchies and arrays to achieve consistency and clarity.
The MRF database can potentially hold UDC number descriptions in several languages but, currently, output from the MRF is distributed in English only although there are incomplete sets of entries in French and German dating from the late 1980s. English remains the working language of the Consortium. The entries in the database will be expanded to include up to date equivalents in other languages in line with Members' demands and resources.
How can I access it?
It should be emphasized that the primary purpose for which the MRF database was originally created and is regularly updated is for the maintenance of the UDC and the distribution of the updated content to Members and licence holders as the source for their publications.
Although it is not designed with end-users in mind, it is an excellent, comprehensive reference tool and is available under licence terms to classifiers, librarians and other users.
Ideally, in bibliographic databases or OPACs, the MRF should be integrated into local cataloguing or indexing systems which provide a familiar and customized interface. The UDC Consortium specifically allows access (under licence) to MRF data in order to encourage the creation of various software applications designed to hold, display and handle UDC schedules or use them invisibly in other applications, such as translation or mapping mechanisms. The UDC Consortium is always ready to discuss such cases and is willing to negotiate terms for active collaboration. At present, the UDC Consortium Executive Members from Russia (VINITI), Spain (AENOR) and the UK (BSI) already provide, or are finalizing, electronic versions of their products containing appropriate front-end applications to help the users access the UDC data. A number of licensees also provide, or are working towards, similar electronic versions. Enquiries on these products or associated services should be directed to the publishers concerned.
Maintenance
Each UDC number in the MRF database, including main and special auxiliary numbers, is held in a separate record. Every piece of data relevant to the UDC number, its meaning, filing, display, source or application, is entered into a separate field (fields in CDS/ISIS are not length limited and each field may have several subfields where necessary). A single MRF record comprises 30 fields grouped into two categories. The first twenty fields are descriptive and represent the actual content of the UDC schedules, the remaining ten are administrative data and contain information relevant to MRF maintenance (see more detail in MRF database design and structure).
Data from the MRF can be exported in two ways: in ISO 2709 format or
as plain text (ASCII). Both versions are available from the UDC Consortium
as specified in the appropriate licence agreement.
ISO 2709 is needed when data are going to be used in ISIS or any other
bibliographic database. For this purpose a separate export utility is
used. It is possible to use different field select tables which will filter
out unwanted fields and export only the selected required fields. For
the purpose of sort and export several special field select tables (FSTs)
are created for maintenance and updating procedures, but CDS/ISIS allows
these to be tailored for particular purposes. For instance, one might
want to extract from the database (or a part of it) only classification
numbers and their descriptions without examples of combination or application
notes. It is possible to define a field select table which will filter
out these fields while exporting the targeted file. The same filtering
principle is used when producing the user version of the MRF which need
not contain all the administrative data contained in fields 901-955. Data
extracted in this way are not normally readable in word processing applications
as they contain special formatting labels and codes.
The plain text version of the MRF is exported using one of the existing printing formats which filters out all the administration fields and contains only those fields used for publishing purposes. For the purpose of text processing and editing, fields are tagged in a simple manner. This facilitates the process of applying a desired style for the display and printing of the schedules. The description of these tags is distributed together with the text version of the MRF.
There are three databases containing MRF records:
- MRF - Contains the most up-to-date version of the
MRF including the most recent officially authorized additions and other
modifications except the cancellations. (This database is continuously
updated, but not distributed, except in special cases). This is the
main database and is used for maintenance of the current schedules.
In addition to a classification number, each record contains a number
of fields for administrative purposes (introduction date, comments,
changes, sources of changes, history, etc.). These fields are not distributed
with the user version of the MRF.
- MRFCAN - Once a classification number is cancelled
in the MRF it is exported to this database. Today this database contains
all officially-authorized cancellations since completion of the MRF
May-June 1993. Each record contains administrative data stating the
date and the source of the cancellation (e.g. volume of Extensions &
corrections in which cancellation is published). These cancellations
are also published on the UDCC Website.
- UMRF (User MRF) and historical databases
The distribution version of the MRF is called the UMRF which consists of records exported from the main MRF without administrative fields. Each year, shortly after the publication of Extensions and Corrections to the UDC and the updating of the MRF, the UMRF version is "frozen" and distributed to subscribers. These "frozen" versions exist for each year from 1993 to the latest (2005). They are officially made at the end of the year and are named yy12 (e.g. 9312 for the version made in December 1993). All are kept by the UDCC for historical reference.
Distribution and licence contracts
The Master Reference File is maintained at the UDC Consortium Headquarters
in the Royal Library at The Hague. It is updated once a year during December/January
to incorporate revisions and amendments published in Extensions
and Corrections to the UDC, normally issued in November of the previous
year in hard copy (and in electronic form since 2002). The distributed
datafile is almost 7 Mb in size. In addition to the updated MRF, each
user is provided with separate files (both text and ISO) containing new
numbers, modifications and cancellations which have already been included
in the current version for that year. Editing instructions and system
files useful in managing the database (Field Definition Tables, Display
and Print Formats) are also included. A guide to the application of the
Master Reference File, called the MRF Manual, is available free of charge
to all Consortium members and licence holders.
As the authorized version of the Universal Decimal Classification, the MRF is available under licence. The terms and costs of licences vary according to the use that is made of data. More information is available here.
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