Template:Certification Table Entry/Sales/DanishPeriod/doc

This helper template calculates periods for Danish certifications, as stated in the following sources:


 * - Album level changed in 1994
 * - levels changed in April 2003
 * - new levels for albums and singles in February 2007
 * - new levels for singles changed in April 2009
 * - new albums levels change in 7 January 2011
 * - new single levels from 17 November 2014
 * - new single levels from 1 April 2016

It returns:

Returns 0 if the data provided is not sufficient.