The definitions taken from SKOS seem altered and incomplete.
For example here is the official definition from SKOS RDF file for altLabel. The Commons version changes the label (using "tag" instead of "label") and omits the comments, one of which is the important (informal) disjointness constraint, and example.
<rdf:Description rdf:about="#altLabel">
<rdfs:label xml:lang="en">alternative label</rdfs:label>
<rdfs:isDefinedBy rdf:resource="http://www.w3.org/2004/02/skos/core"/>
<skos:definition xml:lang="en">An alternative lexical label for a resource.</skos:definition>
<skos:example xml:lang="en">Acronyms, abbreviations, spelling variants, and irregular plural/singular forms may be included among the alternative labels for a concept. Mis-spelled terms are normally included as hidden labels (see skos:hiddenLabel).</skos:example>
<!-- S10 -->
<rdf:type rdf:resource="http://www.w3.org/2002/07/owl#AnnotationProperty"/>
<!-- S11 -->
<rdfs:subPropertyOf rdf:resource="http://www.w3.org/2000/01/rdf-schema#label"/>
<!-- S12 (not formally stated) -->
<rdfs:comment xml:lang="en">The range of skos:altLabel is the class of RDF plain literals.</rdfs:comment>
<!-- S13 (not formally stated) -->
<rdfs:comment xml:lang="en">skos:prefLabel, skos:altLabel and skos:hiddenLabel are pairwise disjoint properties.</rdfs:comment>
<!-- For non-OWL aware applications -->
<rdf:type rdf:resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Property"/>
</rdf:Description>