(2013-05-26) Bernard Vatant: Work in progress. The documentation says "Unofficial Draft".
(2014-05-29) Bernard Vatant: For version 1.0 the declared namespace has been changed to http://rdf-vocabulary.ddialliance.org/xkos#, to be consistent with other DDI vocabularies. The former namespace http://purl.org/linked-data/xkos# still dereferences to the vocabulary.
(2015-05-05) Bernard Vatant: Annual review. Removed false positive 2015 version.