FAIRsharing record for: The UCD1+ controlled vocabulary

This FAIRsharing record describes: This document describes the list of controlled terms used to build the Unified Content Descriptors, Version 1+ (UCD1+). The document describing the UCD1+ can be found at the URL: http://www.ivoa.net/Documents/latest/UCD.html. This document reviews the structure of the UCD1+ and presents the current vocabulary. This version contains new UCD words for the planetary data community as proposed in the Technical Note by Cecconi et al. The suggested list of line labels under the em.line branch is not included. A general solution is currently under study to deal with lists of element instances such spectral lines, chemical elements, elementary particles, etc. using either utypes or a vocabulary.