Template:Certification Table Entry/Sales/DanishStreamingPeriod/doc

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

It returns:
 * - Streaming certification instituted January 7, 2011
 * - levels changed January 30, 2012
 * - levels changed April 30, 2012
 * - levels changed March 21, 2014
 * - canceled November 17, 2014

Returns 0 if the data provided is not sufficient.