Abstract / Description of output
UCDs (Unified Content Descriptors) are metadata that have been used in the VizieR catalogue service since they were first developed in the ESO/CDS data mining project. Because the catalogues currently described by UCDs cover many different domains, UCDs can be used to describe a large fraction of astronomical concepts. The different Virtual Observatory (VO) projects, collaborating in the IVOA (International Virtual Observatory Alliance) have therefore decided to support UCDs, and to collaborate to define a new set of standard metadata. This new set of UCD will be more coherent and complete than the old one. It uses a new syntax, and a list of atomic keywords from which UCDs are built. The sharing of a core set of metadata is very important to ensure interoperability between the various VO elements. We present how this new list of UCDs has been defined, and how it will be expanded in the future. We also present the mechanisms to assign UCDs to (possibly large) datasets, check for validity of UCDs, and make suggestions for including new concepts in the standard core of UCDs. We also discuss several fields of the VO where UCDs will be used, what kind of applications of UCDs are foreseen, how they can be used and how software using UCDs can be designed.
|Title of host publication||Proceedings of Astronomical Data Analysis Software and Systems (ADASS) XIII|
|Publisher||ASTRONOMICAL SOC PACIFIC|
|Publication status||Published - 1 Jul 2004|