DM work package : Utypes definition and syntax

Work is currently taking place in UtypesTigerTeam.

Last iterations on the definitions (presentations @ interop meetings)

This topic is under the Data model pages but also addressed in the TCG Topic page : ?? TCGTopicsUtypes

What are Utypes for

Utypes are names that we can attach to a piece of metadata in order to point to the same concept expressed in a VO data model.
Ex: astrometry statistical error = 0.02 arcsec

This metadata can be represented in the VO using the Characterisation data model by : char:Spatial.Accuracy.StatError.Refval

If we associate "astrometry statistical error" with this utype, we can derive various properties like:

  1. the concept of astrometrical error is the same as the one described in the model.
  2. This concept relies on accuracy along the spatial axis.
  3. If we provide a value with this utype, it is stored in the same type as the data model element and if mentionned in the restricted units defined by the model.

How can I find which Utype is relevant for my data collection

  1. Select an IVOA data model to which you want to be compliant. Ex : Characterisation Data Model
  2. Browse the Utype list and its documentation to select the appropriate Utype list for your metadata description
  3. Check wether all mandatory Utypes are filled in .
- For a Fits image : FITS keyword RESOL will map SpatialAxis.Resolution.RefVal in the Characterisation Data Model utypes list

- For a Fits simple spectrum : FITS keyword SPECTRES will map SpectralAxis.Resolution.RefVal

If you publish your data with CharacterisationDM-v1.11 , you can use the CAMEA VO Tool ( to check the Utype assignation, and verify if your description is compliant to this model.

Topic attachments
I Attachment History Action Size Date Who Comment
XMLxml ObsTAPQueryExample.xml r1 manage 18.6 K 2012-05-23 - 13:52 MireilleLouys example of Query response from ObsTAP
XMLxml PhotDMRegistryRecord.xml r2 r1 manage 2.5 K 2012-05-23 - 15:28 MireilleLouys Example of IVOA DM registration record
Compressed Zip archivezip r2 r1 manage 885.5 K 2012-05-23 - 15:36 MireilleLouys tex and images for Utype draft
PDFpdf WD-Utypes-0.3-20090522.pdf r1 manage 547.0 K 2009-05-25 - 20:31 MireilleLouys Utype preliminary WD
PDFpdf WD-Utypes-0.4-20091107.pdf r1 manage 580.4 K 2009-11-09 - 09:04 MireilleLouys  
Unknown file formattex WD-Utypes-0.4-20091107.tex r1 manage 34.8 K 2011-10-20 - 09:53 MireilleLouys tex version
PDFpdf WD-Utypes-0.7-20120521.pdf r1 manage 647.3 K 2012-05-23 - 14:22 MireilleLouys Utype draft Mai 2012
PDFpdf WD-Utypes-0.7-20120523.pdf r1 manage 647.3 K 2012-05-23 - 15:38 MireilleLouys Utype draft Mai 2012
HTMLhtml note-utype-draft1.5.html r1 manage 34.1 K 2007-01-28 - 13:51 NormanGray Draft Note on UTypes
PDFpdf utype-extra-meeting.pdf r1 manage 273.7 K 2011-11-15 - 19:05 OmarLaurino  
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Topic revision: r17 - 2012-10-23 - MarkusDemleitner
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