University of Glasgow

University of Leicester




Controlled Vocabularies

Vocabularies are a mechanism to formalise the terminology used within a domain of discourse and the semantic relationships between those terms. Typically, a vocabulary is developed to (i) limit the available terms used and (ii) provide consensus on the meaning of the terms.

SKOS is a W3C Proposed Recommendation for publishing and sharing vocabularies on the Semantic Web. A SKOS document captures the information of a vocabulary as RDF statements.

Astronomy Vocabularies

Within the field of astronomy there are many existing vocabularies which have been developed for different purposes by different organisations. These are summaries in the table below. The one exception is the IVOA Thesaurus which is being developed as an updated version of the IAU Thesaurus.

Vocabulary Name Publisher Purpose Size SKOS Version
Astronomy Visualization Metadata(AVM ) IVOA A taxonomy of metadata for tagging images to enable efficient retrieval for outreach purposes. 200-300 terms AVM
Astronomy and Astrophysics Journal keywords (A&A) A&A A set of keywords used for tagging journal articles to summarise their content. 200-300 terms A&A
International Astronomical Union thesaurus (IAU Thesaurus) IAU A thesaurus of astronomical terms published in 1993. (Has not been updated since.) 2,500 terms IAUT
International Virtual Observatory Alliance Thesaurus (IVOAT) IVOA An update of the IAU Thesaurus. ~3,000 terms IVOAT
Universal content descriptors (UCD) IVOA Tags for describing the content of a column in a relational database. 200 terms UCD

As part of the IVOA effort to enable the use of vocabularies within the virtual observatory, we have been involved with developing

These have now been published as an IVOA Proposed Recommendation.

Vocabulary Tools

As part of our effort to help enable the use of vocabularies within the virtual observatory, we have developed three applications for SKOS encoded vocabularies.

Vocabulary Explorer

The Vocabulary Explorer allows a user to discover details about the terms used within a vocabulary, and their relationship to other terms both in the same vocabulary and across vocabularies. To enable the relationship to terms in other vocabularies, mapping files relating the terms in two vocabularies are required. At present, the vocabulary explorer only knows about one such mapping file, linking the astronomy and astrophysics journal keywords to the astronomy visualization metadata taxonomy.

Suggestion Server

The Suggestion Server is an XML-RPC services that offers a limited subset of the functionality of the Vocabulary Explorer. It relies on the same search modules as the Vocabulary Explorer. More details of the location of the service and the available functions can be found on the support page.

A typical interaction with the service would be:

Mapping Editor

The Mapping Editor is a Java application that provides a graphical user interface to enable a user to declare mappings between two vocabularies. Below are three screenshots showing how vocabularies are loaded into the application, and how mappings are expressed. The mapping editor enables the mapping document to be saved as either rdf/xml or turtle notation. Additionally, an existing mapping file can be loaded in and edited.

Loading in vocabulariesVocabulary displayGenerating and displaying mappings