IVOA Semantics Working Group


The Semantics Working Group

Charter for the Semantics WG, approved by EXEC on 17 May 2006:Charter-Semantics.pdf

The Semantics Working Group superseded the UCD Working Group, effective from June 20th, 2006.

Group lead and advising comitee

WG Chair MireilleLouys (2015-)
WG Vice-chair Alberto Accomazzi (2015-)
WG Chair emeritus SebastienDerriere (2006-2012)


UCD list update

Procedure to ask for extension and /or modification of the UCD list

The procedure complies with the following basic principles:

  • Any member of the IVOA community can submit at any time a request for modification (RFM) of the controlled list of UCD words;
  • A globally editable page is the interface between the community and the Scientific Board in charge of discussing the RFM;
  • The author of a RFM should get an answer within 6 weeks;
  • At regular intervals (synchronized with IVOA Interoperability meetings) the approved modifications are integrated in a new version of the IVOA UCD1+ Common Vocabulary.
Current page for request for modification:


Previous RFM pages :

... to come

IVOA Recommendations

Current work

Elaboration of new UCD keywords for planetary metadata.

This new effort is described on the PlanetaryUCD page .

Update of the UCD Maintenance Standard

Latest documents

2017 Update of the UCD Maintenance Standard (initiated at the Shanghai Interop, May 2017)

Version 1.20

Note Version 2.0, 6 June 2017

Note Version 2.0, 6 June 2017 in track change mode from V1.20

This Note is turned to a Working draft proposing the Maintenance Process as an IVOA standard , in coordination with Standards & Process WG.

[[http://wiki.ivoa.net/internal/IVOA/IvoaSemantics/WD-UCDlistMaintenance-2.0-20171018-Trackmode.pdf][WorkingDraft 2.0, 19 October 2017 in track change mode from V1.20]]

Unique identifiers and description for facilities and instruments in astronomy and planetary science (started 2014)

Unified names and identifiers for VO Facilities :Unified Facilities Description UniFacil (on going)

TelescopeInstruments Meetings:

@ the Lisa conference in SXB -2017-June 3-6

Strasbourg @CDS 2018-Feb-21-23 SxbNomenTIMeeting20180221-23

Units specification in the IVOA


  • The VOUnits document is now an IVOA REC. The VOUnitsRFC and DiscussionOnVOUnits pages still exist, but should not now be added to.
  • There are no immediate plans for further work on the standard, however there is a small collection of issues and suggestions at VOUnitsNext

Vocabularies in the IVOA

Documents, releases and drafts are in the VocabulariesWorkingArea


Astronomical Keywords in the era of the Virtual Observatory, IVOA Note AstroKeysTN-20070425.pdf


Ontology of Astronomical Object Types
text: WD_2007-02-19.pdf
OWL file (2008MAY16): ObjectTypes_0.99r.owl

SKOS to OWL script. Basic, but functioning

Semantics/UCD Sessions at Interop Meetings

Where & When WG Session Plenary & More
Madrid – Spain, May 2014 programme
Waikoloa – Hawai`i, USA, Sep 2013 Semantics & Education
Heidelberg – Germany, May 2013 Semantics & DCP
São Paulo – Brazil, Oct 2012 - -
Urbana – USA, May 2012 programme plenary
Pune – India, Oct 2011 programme plenary
Naples – Italy, May 2011 programme plenary
Nara – Japan, Dec 2010 programme plenary
Victoria – Canada, May 2010 programme plenary
Garching – Germany, Nov 2009 InterOpNov2009Sem plenary
Strasbourg – France, May 2009 InterOpMay2009Semantics plenary
Baltimore – USA, Oct 2008 InterOpOct2008Semantics plenary
Trieste – Italy, May 2008 InterOpMay2008Semantics plenary
Beijing – China, May 2007 InterOpMay2007Semantics plenary
Victoria – Canada, May 2006 InterOpMay2006UCD plenary
Madrid – Spain, Oct 2005 InterOpOct2005UCD plenary
Kyoto – Japan, May 2005 InterOpMay2005UCD plenary
Pune – India, September 2004 no formal UCD session plenary
Cambridge, Mass. – USA, May 2004 InterOpMay2004UCD plenary
Strasbourg, October 2003 InterOpOct2003UCD ppt
Cambridge – UK, May 2003 InterOpMay2003UCD .ppt, .pdf

'New Technologies' sessions

These aren't formally 'semantics' sessions, but they've been organised by the Semantics WG

Where & When WG Session Plenary & More
Madrid – Spain, May 2014 programme
Heidelberg – Germany, May 2013 programme PDF

Old documents


WG Roadmap

Date Event status
Oct-2004 UCD1+ to PR (RFC) done
May-2005 UCD-Tools done
Jun-2005 Create Sci- and Tech-Boards done
Jul-2005 UCD1+ word-list to PR(RFC) done (RFC after holidays)
Jul-2005 UCD1+: PR to Recomm done (in Aug, minor editing needed)
Oct-2005 UCD1+ word-list: PR to Recomm in progress
Oct-2005 From UCDs to Semantics proposed in Kyoto
Nov-2005 UCD1+ Words Maintenance Working Draft
Dec-2005 UCD1+ word-list: Recomm done (31Dec2005)
May-2006 UCD1+ Maintenance: Recomm done (28May2006)
End-2006 Ontologies-TN done (31Oct2006)
End-2006 Standard Vocabulary-TN draft
Feb-2007 Ontology-WD?  
Apr-2007 UCD1+ word-list: Recomm (2Apr2007)
Oct-2007 Ontology-UseCase TN  


  • General working-group discussion archive. See the UCD archive for discussion prior to June 20th, 2006.
  • UCD Scientific Board archive
  • UCD Technical Board archive.

Topic attachments
I Attachment Action Size Date Who Comment
PDFpdf Note-UCDlistMaintenance-2.0-20170602.pdf manage 219.8 K 2017-06-02 - 13:33 FrancoiseGenova UCDlistMaintenance V2.0, Note 2 June 2017
PDFpdf Note-UCDlistMaintenance-2.0-20170602_withchanges.pdf manage 271.3 K 2017-06-02 - 13:34 FrancoiseGenova Note UCDlistMaintenance V2.0, showing changes from V1.20
PDFpdf PR-UCDlistMaintenance-2.0-20171018.pdf manage 362.1 K 2017-10-19 - 21:26 MireilleLouys Maintenance Process for the IVOA UCD list
Unknown file formatxsd VOFacility.xsd manage 28.9 K 2015-11-20 - 18:15 MireilleLouys VOresurce extension for the description of VOFacilities: Telescope , space missions , etc. - XML schema
PDFpdf WD-UCDlist-1.3-20150608.pdf manage 748.3 K 2015-06-18 - 13:02 MireilleLouys WD for updated UCDs terms / planetary and solar data
Unknown file formatdocx WD-UCDlist-1.3-20160719.docx manage 85.9 K 2016-10-21 - 06:16 MireilleLouys update on UCD 1.3 WD
PDFpdf WD-UCDlist-1.3-20160719.pdf manage 811.9 K 2016-10-21 - 07:07 MireilleLouys update of UCD vocabulary/ pdf version
PDFpdf WD-UCDlistMaintenance-2.0-20171018-Trackmode.pdf manage 365.8 K 2017-10-20 - 16:10 MireilleLouys maintenance Process for UCD- WD
XSL (XML style sheet)xsl skosToOwl.xsl manage 5.2 K 2010-11-15 - 19:49 BrianThomas SKOS to OWL script. Basic, but functioning.
Topic revision: r74 - 2018-02-22 - MireilleLouys
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