FAIRsharing record for: IVOA Standard for Unified Content Descriptors

This FAIRsharing record describes: The IVOA Standard for Unified Content Descriptors document describes the current understanding of the IVOA controlled vocabulary for describing astronomical data quantities, called Unified Content Descriptors (UCDs). The present document defines a new standard (named UCD1+) improving the first generation of UCDs (UCD1). The basic idea is to adopt a new syntax and vocabulary requiring little effort for people to adapt software already using UCD1. This document also addresses the questions of maintenance and evolution of the UCD1+. Examples of use cases within the Virtual Observatory and tools for using UCD1+ are also described.