'period:date ref'

http://finregont.com/fro/xbrl/formula/period.ttl#dateRef
Property 'period:date ref'

sxml:tag

http://xbrl.org/2008/filter/period#date

rdf:type

owl:ObjectProperty

rdfs:label

date ref

References
as rdfs:subClassOf (period:Date-time.model, period:Date-time.model)