Hi,
regarding an actual topic in Germany about publication of the
timetable-data of Deutsche Bahn (German national railway company) and
their willingness of a discussion with other Open-Data-Supporters it may
be a good idea of providing an expiration dates for Wikidata-records.
In their open letter to Mr. Kreil [1] they announced that it may cause
problems providing the timetable-data in an open way if e.g. anybody
uses old data.
Marco
[1]
http://www.db-vertrieb.com/db_vertrieb/view/service/open_plan_b.shtml