Vocabularies in the VO 2 Proposed Recommendation: Request for Comments

Vocabularies in the VO, version 2, proposes formats and practices to manage hierarchical word lists that need consensus within the VO. See http://ivoa.net/rdf the vocabularies currently in use or under consideration.

Note that this is not “Semantics in the VO”, i.e., further applications of RDF (e.g., full ontologies) are by no means excluded by this specification.

Latest version of Vocabularies in the VO 2 can be found at:

A build of svn trunk with some typos removed is available at https://docs.g-vo.org/Vocabularies.pdf

Reference Interoperable Implementations

Vocabularies of the type described here are in use by several existing standards:

  • Datalink (the semantics column)
  • VOTable (TIMESYS time scales and reference positions)
  • VOResource (relationship types, content levels, content types, date roles, prospectively the subject keywords)
  • SimpleDALRegExt (under review: product types)
  • VODataService (under review: messengers)

The code managing the RDF repository is available at https://volute.g-vo.org/svn/trunk/projects/semantics/voc-source

Implementations on the consumer side:

  • stilts' VOTable validator uses vocabularies to check the TIMESYS attributes (this gives a simple example for how to deal with IVOA vocabularies in Java)
  • pyVO will use the Datalink vocabulary for query expansion in the bysemantics method (https://github.com/astropy/pyvo/pull/241). This gives an example for how to use vocabularies from Python
  • Sembarebro is an example for how to use vocabularies from Javascript (code)
  • Another example for using IVOA vocabularies from python is the implementation of the gavo_vocmatch ADQL User Defined Function in DaCHS. See http://dc.g-vo.org/tap/capabilities for a definition of the UDF (Code, around line 526)
  • A somewhat more complex use case is using the UAT hierarchy in mapping metadata, which again contains examples for vocabulary use in Python.

On processes defined:

  • several VEPs have been run
  • a PEN has been produced for vocabulary adoption: https://ivoa.net/documents/uat-as-upstream/20201117/ – it is probably a good idea to give this a brief look, too, when reviewing Vocabularies 2. Perhaps these Vocabularies 2 should give some constraints what must minimally be addressed in this kind of document

Plans for the consumer side:

  • The RofR publishing registry validator should use the VOResource vocabularies; we expect this to happen during RFC.

Implementations Validators

The vocabulary process itself is in some sense self-validating because the input files are parsed and mangled. A “deeper” validation (“are these concepts any good?”; “can people work out from a description what is and what is not within the concept?”) is probably beyond what automated validators can do.

As to the external interface, common RDF validators can be used to check the syntactic correctness of our artefacts, for instance the W3C RDF validator.

Comments from the IVOA Community during RFC/TCG review period: 2021-03-22 through 2021-05-03

The comments from the TCG members during the RFC/TCG review should be included in the next section.

In order to add a comment to the document, please edit this page and add your comment to the list below in the format used for the example (include your Wiki Name so that authors can contact you for further information). When the author(s) of the document have considered the comment, they will provide a response after the comment.

Additional discussion about any of the comments or responses can be conducted on the WG mailing list. However, please be sure to enter your initial comments here for full consideration in any future revisions of this document

Comments from TCG member during the RFC/TCG Review Period: 2021-03-22 through 2021-05-03

WG chairs or vice chairs must read the Document, provide comments if any (including on topics not directly linked to the Group matters) or indicate that they have no comment.

IG chairs or vice chairs are also encouraged to do the same, althought their inputs are not compulsory.

TCG Chair & Vice Chair

Applications Working Group

Data Access Layer Working Group

Data Model Working Group

Grid & Web Services Working Group

Registry Working Group

Semantics Working Group

Data Curation & Preservation Interest Group

Education Interest Group

Knowledge Discovery Interest Group

Solar System Interest Group

Theory Interest Group

Time Domain Interest Group


Accept. -- MarkTaylor - 2021-03-20

Standards and Processes Committee


If you have minor comments (typos) on the last version of the document please indicate it in the Comments column of the table and post them in the TCG comments section above with the date.

Group Yes No Abstain Comments
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Topic revision: r3 - 2021-03-22 - MarkusDemleitner
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