User:Muhandes/Certification Table Entry/Sales/BelgianPeriod/doc

This helper template calculates periods for Belgian certifications, as stated in the following source:

There is no data for the interim period
 * - certification until 2006
 * - certification from October 2007
 * - certification from 2009 (changed on April 2008 )
 * - certification from July 2018

It returns:

Returns 0 if the data provided is insufficient