(2013-04-14) Ghislain Atemezing: This ontology references a version of SKOS in the Last Call Edition (see: http://www.w3.org/TR/2008/WD-skos-reference-20080829/skos.html#). So, we are not sure if the stable version of SKOS breaks the current implementation.
(2014-04-09) Bernard Vatant: Annual review. No evolution, no correction of the SKOS namespace.