Trying to map one of our properties to something close to http://id.loc.gov/ontologies/bibframe/legalDate.rdf "Date of legal work, or promulgation of a law, or signing of a treaty"

I see usages primarily of inception (P571) https://www.wikidata.org/wiki/Property:P571 point in time (P585) https://www.wikidata.org/wiki/Property:P585

Suggestions?

-Thad +ThadGuidry https://plus.google.com/+ThadGuidry