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Library of Congress Launches Beta Release of Linked Data Classification

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A while back I  mentioned the Library of Congress was looking at ways to provide the Library of Congress Classification (LCC) as linked data. I am happy to report linked data versions of several classes have been released in beta on the LC Linked Data Service by the Network Development and Metadata Standards Office (NDMSO). These classes are B (Philosophy, Psychology, and Religion), M (Music), N (Fine Arts), and Z (Bibliography, Library Science, and Information Resources). For this initial beta release, the Linked Data Service has generated linked data resources for each classification number and classification range within the entire class hierarchy for B, M, N, and Z.

Here is a nice example of a classification record from the LC Linked Data Service, which corresponds to classification number ND623.B9 (Buonarroti, Michelangelo, 1475-1564) from Class N (Fine Arts):

Screenshot from
Screenshot of ND623.B9 from (Click on the image to see the full record.)

At the top of the screen you can see the hierarchy of Class N going down to the caption for Michelangelo. Just below that you will see the dereferenceable URI for the classification number. If we scroll down the page a bit, we can see broader and narrower terms are provided as well as links to the RDF, SKOS, and MADS (MARC/XML) formats:

Screenshot of ND623.B9 from continued

As I mentioned this is just a beta version, so there are a few things to keep in mind while you explore. First, right now only Classes B, M, N, and Z are available on, but we are hoping more classes will follow very soon. Second, this project is under active development, so bulk download of the classification is not available at this time. Third, the Linked Data Service team would very much appreciate feedback about how you would like to use this kind of data, so they can better serve the community’s needs.

Here in the Law Library we are anxiously awaiting the conversion of Class K (Law) to linked data, but there are many good reasons why the LC Linked Data Service chose to start with the classes listed above. The primary and most compelling reason why Class K was not chosen for the first foray into a linked data representation of classification is the sheer size of the class. Jolande Goldberg, Law Classification Specialist at the Policy and Standards Division of the Library of Congress, estimates Class K to make up more than half of the data in the entire LCC!

Additionally, as any legal cataloger will tell you, Class K is full of all kinds of interesting tables needed to create a complete classification number. All these tables will need to be extrapolated into linked data as well. Semantic experts at LC have already devised a way to generate URIs and resources for the schedules and tables needed to create a classification number for the smaller classes like B and N. But duplicating that process for Class K is going to require a different level of processing power entirely. Can you feel that heat? It’s our poor servers endlessly churning away at the mountains of data and relationships buried in Class K!

So for now, we hope you enjoy this first look at a linked data version of classification. We’ll keep you posted as new developments occur.


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