Indicates (by URL or string) a particular version of a schema used in some CreativeWork. This property was created primarily to
indicate the use of a specific schema.org release, e.g.
10.0 as a simple string, or more explicitly via URL,
http://schema.org/docs/releases.html#v10.0. There may be situations in which other schemas might usefully be referenced this way, e.g.
http://dublincore.org/specifications/dublin-core/dces/1999-07-02/ but this has not been carefully explored in the community.